Edgar Filing: Spirit Airlines, Inc.

10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)



þ	ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2015



	TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File No. 001-35186

Spirit Airlines, Inc.

(Exact name of registrant as specified in its charter)




Delaware		38-1747023
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

2800 Executive Way Miramar, Florida		33025
(Address of principal executive offices)		(Zip Code)

(954) 447-7920

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:




Title of Each Class		Name of Each Exchange on Which Registered
Voting Common Stock, $0.0001 par value Non-Voting Common Stock, $0.0001 par value		NASDAQ Global Select Market None

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes þ No ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ¨ No þ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes þ No ¨

Indicate by checkmark whether the registrant has submitted electronically and posted on its corporate Website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes þ No ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. þ

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer þ Accelerated filer ¨ Non-accelerated filer ¨ Smaller reporting company ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes ¨ No þ

The aggregate market value of the common stock held by non-affiliates of the registrant was approximately $4.5 billion computed by reference to the last sale price of the common stock on the NASDAQ Global Select Market on June 30, 2015, the last trading day of the registrant’s most recently completed second fiscal quarter. Shares held by each executive officer, director and by certain persons that own 10 percent or more of the outstanding Common Stock have been excluded in that such persons may be deemed to be affiliates. This determination of affiliate status is not necessarily a conclusive determination for other purposes.

The number of shares of each registrant's classes of common stock outstanding as of the close of business on February 10, 2016:



Class	Number of Shares
Common Stock, $0.0001 par value per share	71,546,675

Documents Incorporated by Reference

Portions of the registrant's Proxy Statement for the registrant's 2016 Annual Meeting of Stockholders are incorporated by reference into Part III of this Form 10-K to the extent stated herein. The Proxy Statement will be filed within 120 days of the registrant's fiscal year ended December 31, 2015.

TABLE OF CONTENTS



PART I	Page
Item 1. Business	4
Item 1A. Risk Factors	13
Item 1B. Unresolved Staff Comments	30
Item 2. Properties	30
Item 3. Legal Proceedings	31
Item 4. Mine Safety Disclosures	31
PART II
Item 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	32
Item 6. Selected Financial Data	35
Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations	38
Item 7A. Quantitative and Qualitative Disclosures About Market Risk	61
Item 8. Financial Statements and Supplementary Data	62
Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	96
Item 9A. Controls and Procedures	96
Item 9B. Other Information	96
PART III
Item 10. Directors, Executive Officers and Corporate Governance	97
Item 11. Executive Compensation	97
Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	97
Item 13. Certain Relationships and Related Transactions and Director Independence	97
Item 14. Principal Accountant Fees and Services	97
PART IV
Item 15. Exhibits and Financial Statement Schedules	98
Signatures	99

__________________________________________________

PART I

ITEM 1. BUSINESS

Overview

Spirit Airlines is an ultra low-cost, low-fare airline that offers affordable travel to price-conscious customers. Our all-Airbus Fit Fleet^TM, the youngest fleet of any major U.S. airline, currently operates more than 385 daily flights to 56 destinations in the United States, Caribbean and Latin America. Our stock trades on the NASDAQ Global Select Stock Market under the symbol "SAVE."

Our ultra low-cost carrier, or ULCC, business model allows us to compete principally by offering customers our Bare Fares ^TM, which are unbundled base fares that remove components traditionally included in the price of an airline ticket. We then give customers Frill Control ^TM, which provides customers the freedom to save by paying only for the options they choose such as bags, advance seat assignments and refreshments. We record revenue related to these options in our financial statements as non-ticket revenue.

Our History and Corporate Information

We were founded in 1964 as Clippert Trucking Company, a Michigan corporation. We began air charter operations in 1990 and renamed ourselves Spirit Airlines, Inc. in 1992. In 1994, we reincorporated in Delaware, and in 1999 we relocated our headquarters to Miramar, Florida.

Our mailing address and executive offices are located at 2800 Executive Way, Miramar, Florida 33025, and our telephone number at that address is (954) 447-7920. We are subject to the information and periodic reporting requirements of the Securities Exchange Act of 1934, or Exchange Act, and, in accordance therewith, file periodic reports, proxy statements and other information with the Securities and Exchange Commission or SEC. Such periodic reports, proxy statements and other information are available for inspection and copying at the SEC's Public Reference Room at 100 F Street, NE., Washington, DC 20549 or may be obtained by calling the SEC at 1-800-SEC-0330. In addition, the SEC maintains a website at http://www.sec.gov that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC. We also post on the Investor Relations page of our website, www.spirit.com, a link to our filings with the SEC, our Corporate Governance Guidelines and Code of Business Conduct and Ethics, which applies to all directors and all our employees, and the charters of our Audit, Compensation, Finance, Safety, Security and Operations and Nominating and Corporate Governance committees. Our filings with the SEC are posted as soon as reasonably practical after they are filed electronically with the SEC. Please note that information contained on our website is not incorporated by reference in, or considered to be a part of, this report. You can also obtain copies of these documents free of charge by writing to us at: Corporate Secretary, Spirit Airlines, Inc., 2800 Executive Way, Miramar, Florida 33025.

Our Business Model

Our ULCC business model provides customers low, unbundled base fares with a range of optional services, allowing customers the freedom to choose only the options they value. The success of our model is driven by our low cost structure, which permits us to offer low base fares while maintaining high profit margins.

We are focused on price-sensitive travelers who pay for their own travel, and our business model is designed to deliver what we believe our customers want: low fares. We aggressively use low fares to address an underserved market, which helps us to increase passenger volume, load factors and non-ticket revenue on the flights we operate. We also have high-density seating configurations on our aircraft and a simplified onboard product designed to lower costs, which is part of our Plane Simple^TMstrategy. High passenger volumes and load factors help us sell more ancillary products and services, which in turn allows us to reduce the base fare we offer even further. We strive to be recognized by our customers and potential customers as the low-fare leader in the markets we serve.

We compete based on total price. We believe other airlines have used an all-inclusive price concept to effectively maintain higher total prices to consumers, rather than lowering fares by unbundling each product or service. For example, carriers that tout “free bags” have included the cost of checking bags in the total ticket price, which does not allow passengers to see how much they would save if they did not check luggage. We believe that we and our customers benefit when we allow our customers to know the total price of their travel by breaking out the cost of optional products or services.

We allow our customers to see all available options and their respective prices prior to purchasing a ticket, and this full transparency illustrates that our total price, including options selected, is lower than other airlines on average. In 2014, we

launched a new brand campaign, which we continued in 2015, to educate the public on how Spirit's unbundled pricing model works and how that gives them choice and saves them money compared to other airlines.

Our Strengths

We believe we compete successfully in the airline industry by leveraging the following demonstrated business strengths:

Ultra-Low Cost Structure. Our unit operating costs are among the lowest of all airlines operating in the United States. We believe this unit cost advantage helps protect our market position and enables us to offer some of the lowest base fares in our markets, sustain among the highest operating margins in our industry and support continued growth. Our operating costs per available seat mile (CASM) of 7.68 cents in 2015 were significantly lower than those of the major domestic network carriers and among the lowest of the domestic low-cost carriers. We achieve these low unit operating costs in large part due to:


•	high aircraft utilization;


•	high-density seating configurations on our aircraft, which is part of our Plane Simple ^TMstrategy along with simplified onboard product designed to lower costs;


•	no hub-and-spoke network inefficiencies;


•	highly productive workforce;


•	opportunistic outsourcing of operating functions;


•	operating our Fit Fleet ^TM, a single-fleet type of Airbus A320-family aircraft that is the youngest fleet of any major U.S. airline and operated by common flight crews;


•	reduced sales, marketing and distribution costs through direct-to-consumer marketing;


•	efficient flight scheduling, including minimal ground times between flights; and


•	a company-wide business culture that is keenly focused on driving costs lower.

Innovative Revenue Generation. We execute our innovative, unbundled pricing strategy to generate significant non-ticket revenue, which allows us to lower base fares and enables our passengers to identify, select and pay for only the products and services they want to use. In implementing our unbundled strategy, we have grown average non-ticket revenue per passenger flight segment from approximately $5 in 2006 to $54 in 2015 by:


•	charging for checked and carry-on baggage;


•	passing through all distribution-related expenses;


•	charging for premium seats and advance seat selection;


•	maintaining consistent ticketing policies, including service charges for changes and cancellations;


•	generating subscription revenue from our $9 Fare Club low-fare subscription service;


•	deriving brand-based revenues from proprietary services, such as our FREE SPIRIT affinity credit card program;


•	offering third-party travel products (travel packages), such as hotel rooms, ground transportation (rental and hotel shuttle products) and attractions (show or theme park tickets) packaged with air travel on our website;


•	selling third-party travel insurance through our website; and


•	selling onboard advertising.

Resilient Business Model and Customer Base. By focusing on price-sensitive travelers, we have maintained profitability during volatile economic periods because we are not highly dependent on premium-fare business traffic. We believe our growing customer base is more resilient than the customer bases of most other airlines because our low fares and unbundled service offering appeal to price-sensitive travelers. In 2015, low oil prices coupled with increased competition in the U.S. drove lower unit revenues, but lower costs produced margins that remain higher than most of our domestic network peers.

Well Positioned for Growth. We have developed a substantial network of destinations in profitable U.S. domestic niche markets, targeted growth markets in the Caribbean and Latin America and high-volume routes flown by price-sensitive travelers. In the United States, we also have grown into large markets that, due to higher fares, have priced out those more price-sensitive travelers. We seek to balance growth between large domestic markets, niche markets and opportunities in the Caribbean and Latin America according to current economic and industry conditions.

Experienced International Operator. We believe we have substantial experience in foreign local aviation, security and customs regulations, local ground operations and flight crew training required for successful international and overwater flight operations. All of our aircraft are certified for overwater operations. We believe we compete favorably against other low-cost carriers because we have been conducting international flight operations since 2003 and have developed substantial experience in complying with the various regulations and business practices in the international markets we serve. During 2015, 2014 and 2013, no revenue from any one foreign country represented greater than 4% of the our total passenger revenue. We attribute operating revenues by geographic region based upon the origin and destination of each passenger flight segment.

Financial Strength Achieved with Focus on Cost Discipline. We believe our ULCC business model has delivered strong financial results in both favorable and more difficult economic times. We have generated these results by:


•	keeping a consistent focus on maintaining low unit operating costs;


•	ensuring our sourcing arrangements with key third parties are regularly benchmarked against the best industry standards;


•	generating and maintaining an adequate level of liquidity to insulate against volatility in key cost inputs, such as fuel, and in passenger demand that may occur as a result of changing general economic conditions.

Route Network

As of December 31, 2015, our route network included 191 markets served by 56 airports throughout North America, Central America, South America and the Caribbean.

Below is a route map of our current network, which includes seasonal routes and routes announced as of February 8, 2016 for which service has not yet started:

Our network expansion targets underserved and/or overpriced markets. We employ a rigorous process to identify opportunities to deploy new aircraft where we believe they will be most profitable. To monitor the profitability of each route, we analyze weekly and monthly profitability reports as well as near term forecasting.

Competition

The airline industry is highly competitive. The principal competitive factors in the airline industry are fare pricing, total price, flight schedules, aircraft type, passenger amenities, number of routes served from a city, customer service, safety record and reputation, code-sharing relationships and frequent flier programs and redemption opportunities. Our competitors and potential competitors include traditional network airlines, other low-cost carriers and ULCCs, and regional airlines. We typically compete in markets served by traditional network airlines, and other low-cost carriers and ULCCs, and, to a lesser extent, regional airlines.

As of December 31, 2015, our top two largest network overlaps are with Southwest Airlines and American Airlines at approximately 55% and 50% of our markets, respectively. Our principal competitors on domestic routes are Southwest Airlines, American Airlines, United Airlines and Delta Air Lines. Our principal competitors for service from South Florida to our markets in the Caribbean and Latin America are American Airlines, through its hub in Miami, and JetBlue Airways and Southwest Airlines, through their operations in Fort Lauderdale. Our principal competitive advantage is our low base fares. We are able to offer low fares profitably, due to our low unit operating costs, which in 2015 were among the lowest in the U.S. airline industry. In difficult economic or competitive environments, we believe our low unit costs coupled with our relatively stable non-ticket revenues allow us to price our fares at levels where we can be profitable while our primary competitors cannot.

The airline industry is particularly susceptible to price discounting because, once a flight is scheduled, airlines incur only nominal incremental costs to provide service to passengers occupying otherwise unsold seats. The expenses of a scheduled aircraft flight do not vary significantly with the number of passengers carried and, as a result, a relatively small change in the number of passengers or in pricing could have a disproportionate effect on an airline’s operating and financial results. Price competition occurs on a market-by-market basis through price discounts, changes in pricing structures, fare matching, target promotions and frequent flier initiatives. Airlines typically use discount fares and other promotions to stimulate traffic during normally slower travel periods to generate cash flow and to maximize TRASM. The prevalence of discount fares can be particularly acute when a competitor has excess capacity that it is unable to fill at higher rates. A key element to our competitive strategy is to maintain very low unit costs in order to permit us to compete successfully in price-sensitive markets.

Seasonality

Our business is subject to significant seasonal fluctuations. We generally expect demand to be greater in the second and third quarters compared to the rest of the year. The air transportation business is also volatile and highly affected by economic cycles and trends.

Distribution

The majority of our tickets are sold through direct channels including online via www.spirit.com, our call center and our airport ticket counters, with spirit.com being the primary channel. We also partner with a number of third parties to distribute our tickets, including online and traditional travel agents and electronic global distribution systems.

Customers

We believe our customers are primarily leisure travelers who are paying for their own ticket and who make their purchase decision based largely on price. By maintaining a low cost structure, we can successfully sell tickets at low fares while maintaining a strong profit margin.

Customer Service

We are committed to taking care of our customers. We believe focusing on customer service in every aspect of our operations including personnel, flight equipment, in-flight and ancillary amenities, on-time performance, flight completion ratios, and baggage handling will strengthen customer loyalty and attract new customers. We proactively aim to improve our operations to ensure further improvement in customer service.

In response to customer and other demands, we modified our online booking process to allow our customers to see all available options and their prices prior to purchasing a ticket, and have initiated a campaign that illustrates our total prices are lower, on average, than those of our competitors, even when options are included.

Fleet

We fly only Airbus A320 family aircraft, which provides us significant operational and cost advantages compared to airlines that operate multiple aircraft types. By operating a single aircraft type, we avoid the incremental costs of training crews across multiple types. Flight crews are entirely interchangeable across all of our aircraft, and maintenance, spare parts inventories and other operational support remains highly simplified compared to those airlines with more complex fleets. Due to this commonality among Airbus single-aisle aircraft, we can retain the benefits of a fleet comprised of a single type of aircraft while still having the flexibility to match the capacity and range of the aircraft to the demands of each route.

As of December 31, 2015, we had a fleet of 79 Airbus single-aisle aircraft, which are commonly referred to as “A320 family” aircraft. A320 family aircraft include the A319, A320 and A321 models, which have broadly common design and equipment but differ most notably in fuselage length, service range and seat capacity. Within the A320 family of aircraft, models using existing engine technology may carry the suffix “ceo,” denoting the “current engine option,” while models equipped with new-generation engines (available starting in 2016) may carry the suffix “neo,” denoting the “new engine option.” As of December 31, 2015, our fleet consisted of 29 A319s, 42 A320s and 8 A321s, and the average age of the fleet was 5.2 years. As of December 31, 2015, we owned 18 of our aircraft, of which 15 aircraft are financed through senior and junior long-term debt with terms of 12 and 7 years, respectively, and 3 aircraft are financed through enhanced equipment trust certificates (EETCs). See “Notes to the Financial Statements—9. Debt and Other Obligations.” The remaining 61 of our aircraft are financed under operating leases with expirations between 2016 and 2027.

As of December 31, 2015, firm aircraft orders consisted of 87 A320 family aircraft (13 A320ceos, 40 A320neos, 24 A321ceos and 10 A321neos) with Airbus and an additional 5 direct operating leases for A320neos with a third-party lessor. As of December 31, 2015, spare engine orders consisted of four V2500 SelectOne engines with IAE and nine PurePower PW 1100G-JM engines with Pratt & Whitney. Aircraft are scheduled for delivery from 2016 through 2021 and spare engines are scheduled for delivery from 2017 through 2023. The firm aircraft orders provide for capacity growth as well as the flexibility to replace some, none or all of the 79 aircraft in our present fleet. We may elect to supplement these deliveries by additional acquisitions from the manufacturer or in the open market if demand conditions merit. We also may adjust or defer deliveries, or change models of aircraft in our delivery stream, from time to time, as a means to match our future capacity with anticipated demand and growth trends.

Consistent with our ULCC business model, each of our aircraft is configured with a high density seating configuration, which helps us maintain a lower unit cost and pass savings to our customers. Our high density seating configuration accommodates more passengers than those of our competitors when comparing the same type of aircraft.

Maintenance and Repairs

We have a Federal Aviation Administration (FAA) mandated and approved maintenance program, which is administered by our technical services department. Our maintenance technicians undergo extensive initial and ongoing training to ensure the safety of our aircraft.

Aircraft maintenance and repair consists of routine and non-routine maintenance, and work performed is divided into three general categories: line maintenance, heavy maintenance and component service. Line maintenance consists of routine daily and weekly scheduled maintenance checks on our aircraft, including pre-flight, daily, weekly and overnight checks, and any diagnostics and routine repairs and any unscheduled items on an as needed basis. Line maintenance events are currently serviced by in-house mechanics supplemented by contract labor and are primarily completed at airports we currently serve. Heavy airframe maintenance checks consist of a series of more complex tasks that can take from one to four weeks to accomplish and typically are required approximately every 24 months. Heavy engine maintenance is performed approximately every four to six years and includes a more complex scope of work. Due to our relatively small fleet size and projected fleet growth, we believe outsourcing all of our heavy maintenance activity, such as engine servicing, major part repair and component service repairs is more economical. Outsourcing eliminates the substantial initial capital requirements inherent in heavy aircraft maintenance. We have entered into a long-term flight hour agreement for our current fleet and future deliveries with IAE and Pratt & Whitney for our engine overhaul services and with Lufthansa Technik on an hour-by-hour basis for component services. We outsource our heavy airframe maintenance to FAA-qualified maintenance providers.

Our recent maintenance expenses have been lower than what we expect to incur in the future because of the relatively young age of our aircraft fleet. Our maintenance costs are expected to increase as the scope of repairs increases with the increasing age of our fleet. As our aircraft age, scheduled scope of work and frequency of unscheduled maintenance events is likely to increase like any maturing fleet. Our aircraft utilization rate could decrease with the increase in aircraft maintenance.

Employees

Our business is labor intensive, with labor costs representing approximately 23.2%, 19.9% and 19.1% of our total operating costs for 2015, 2014 and 2013, respectively. As of December 31, 2015, we had 1,266 pilots, 2,075 flight attendants, 35 flight dispatchers, 499 mechanics, 517 airport agents/other and 455 employees in administrative roles for a total of 4,847 employees. As of December 31, 2015, approximately 73% of our employees were represented by four labor unions. On an average full-time equivalent basis, for the full year 2015, we had 4,326 employees, compared to 3,722 in 2014.

FAA regulations require pilots to have commercial licenses with specific ratings for the aircraft to be flown and be medically certified as physically fit to fly. FAA and medical certifications are subject to periodic renewal requirements, including recurrent training and recent flying experience. Mechanics, quality-control inspectors and flight dispatchers must be certificated and qualified for specific aircraft. Flight attendants must have initial and periodic competency training and qualification. Training programs are subject to approval and monitoring by the FAA. Management personnel directly involved in the supervision of flight operations, training, maintenance and aircraft inspection must also meet experience standards prescribed by FAA regulations. All safety-sensitive employees are subject to pre-employment, random and post-accident drug testing.

The Railway Labor Act, or RLA, governs our relations with labor organizations. Under the RLA, our collective bargaining agreements generally do not expire, but instead become amendable as of a stated date. If either party wishes to modify the terms of any such agreement, they must notify the other party in the manner agreed to by the parties. Under the RLA, after receipt of such notice, the parties must meet for direct negotiations. If no agreement is reached, either party may request the National Mediation Board, or NMB, to appoint a federal mediator. The RLA prescribes no set timetable for the direct negotiation and mediation process. It is not unusual for those processes to last for many months, and even several years. If no agreement is reached in mediation, the NMB in its discretion may declare at some time that an impasse exists. If an impasse is declared, the NMB proffers binding arbitration to the parties. Either party may decline to submit to arbitration. If arbitration is rejected by either party, a 30-day “cooling off” period commences. During that period (or after), a Presidential Emergency Board, or PEB, may be established, which examines the parties’ positions and recommends a solution. The PEB process lasts for 30 days and is followed by another “cooling off” period of 30 days. At the end of a “cooling off” period, unless an agreement is reached or action is taken by Congress, the labor organization and the airline each may resort to “self-help,” including, for the labor organization, a strike or other labor action, and for the airline, the imposition of any or all of its proposed amendments and the hiring of new employees to replace any striking workers. Congress and the President have the authority to prevent “self-help” by enacting legislation that, among other things, imposes a settlement on the parties. The table below sets forth our employee groups and status of the collective bargaining agreements.



Employee Groups	Representative	Amendable Date
Pilots	Air Line Pilots Association, International (ALPA)	August 2015
Flight Attendants	Association of Flight Attendants (AFA-CWA)	August 2007
Dispatchers	Transport Workers Union (TWU)	August 2018
Ramp Service Agents	International Association of Machinists and Aerospace Workers (IAMAW)	June 2020

In August 2014, under the supervision of the NMB and in conjunction with AFA-CWA, we reached a tentative agreement for a five-year contract with our flight attendants. The tentative agreement was subject to ratification by the flight attendant membership. On October 1, 2014, we were notified that the flight attendants voted not to ratify the tentative agreement. We will continue to work with the AFA-CWA and the NMB toward a goal of reaching a mutually beneficial agreement.

On July 8, 2014, certain ramp service agents directly employed by us voted to be represented by the IAMAW. In May 2015, we entered into a five-year interim collective bargaining agreement with the IAMAW, including material economic terms, and we are continuing the process of negotiating a final collective bargaining agreement with the IAMAW. As of December 31, 2015, these ramp service agents served 1 of the 56 airports where we operate.

In August 2015, our Collective Bargaining Agreement (CBA) with ALPA, became amendable. We are currently in discussions with ALPA on a new contract.

We focus on hiring highly productive employees and, where feasible, designing systems and processes around automation and outsourcing in order to maintain our low cost base.

Safety and Security

We are committed to the safety and security of our passengers and employees. We strive to comply with or exceed health and safety regulation standards. In pursuing these goals, we maintain an active aviation safety program. All of our personnel are expected to participate in the program and take an active role in the identification, reduction and elimination of hazards.

Our ongoing focus on safety relies on training our employees to proper standards and providing them with the tools and equipment they require so they can perform their job functions in a safe and efficient manner. Safety in the workplace targets several areas of our business including: flight operations, maintenance, in-flight, dispatch and station operations. The Transportation Security Administration, or TSA, is charged with aviation security for both airlines and airports. We maintain active, open lines of communication with the TSA at all of our locations to ensure proper standards for security of our personnel, customers, equipment and facilities are exercised throughout our business.

Insurance

We maintain insurance policies we believe are customary in the airline industry and as required by the Department of Transportation (DOT). The policies principally provide liability coverage for public and passenger injury; damage to property; loss of or damage to flight equipment; fire and extended coverage; directors’ and officers’ liability; advertiser and media liability; cyber risk liability; fiduciary; and workers’ compensation and employer’s liability. As of July 2014, we obtained third-party war risk (terrorism) insurance from the commercial market. Prior to July 2014, we obtained this insurance through a special program administered by the FAA, which was discontinued in late 2014. Renewing coverage from commercial underwriters could result in a change in premium and more restrictive terms. Although we currently believe our insurance coverage is adequate, there can be no assurance that the amount of such coverage will not be changed or that we will not be forced to bear substantial losses from accidents. Our current war risk (terrorism) insurance policy expires in July 2016.

Management Information Systems

We have continued our commitment to technology improvements to support our ongoing operations and initiatives. During 2013, we completed the integration of a new SAP Enterprise Resource Planning application, which replaced our general ledger, accounts payable, accounts receivable, cash management and fixed asset systems. The conversion was designed to improve our key business processes by implementing an integrated tool to increase efficiency, consistency, data accuracy and cost effectiveness. During 2015, we completed the integration of TRAX, a new scalable maintenance, repair, operations (MRO) system to improve the tracking of all maintenance related financial transactions. We intend to continue to invest time and resources in upgrading and improving our information systems and the security of our data.

Foreign Ownership

Under DOT regulations and federal law, we must be controlled by U.S. citizens. In order to qualify, at least 75% of our stock must be voted by U.S. citizens, and our president and at least two-thirds of our board of directors and senior management must be U.S. citizens.

We believe we are currently in compliance with such foreign ownership rules.

Government Regulation

Operational Regulation

The airline industry is heavily regulated, especially by the federal government. Two of the primary regulatory authorities overseeing air transportation in the United States are the DOT and the FAA. The DOT has jurisdiction over economic issues affecting air transportation, such as competition, route authorizations, advertising and sales practices, baggage liability and disabled passenger transportation, among other areas, several of which were included in rules that became effective in 2011 and 2012 relating to, among other things, how airlines handle interactions with passengers through advertising, the reservation process, at the airport and on board the aircraft. Additional consumer rules proposed in 2014 that would require airlines to disclose through all points of sale the fees for certain basic ancillary services associated with the air transportation consumers are buying or considering buying may be implemented in 2016. Additional disabled passenger rules may be proposed in 2016. See “Risk Factors—Restrictions on or increased taxes applicable to charges for ancillary products and services paid by airline passengers and burdensome consumer protection regulations or laws could harm our business, results of operations and financial condition.”

The DOT has authority to issue certificates of public convenience and necessity required for airlines to provide air transportation. We hold a DOT certificate of public convenience and necessity authorizing us to engage in scheduled air transportation of passengers, property and mail within the United States, its territories and possessions and between the United

States and all countries that maintain a liberal aviation trade relationship with the United States (known as “open skies” countries). We also hold DOT certificates to engage in air transportation to certain other countries with more restrictive aviation policies.

The FAA is responsible for regulating and overseeing matters relating to air carrier flight operations, including airline operating certificates, aircraft certification and maintenance and other matters affecting air safety. The FAA requires each commercial airline to obtain and hold an FAA air carrier certificate. This certificate, in combination with operations specifications issued to the airline by the FAA, authorizes the airline to operate at specific airports using aircraft approved by the FAA. As of December 31, 2015, we had FAA airworthiness certificates for all of our aircraft, we had obtained the necessary FAA authority to fly to all of the cities we currently serve, and all of our aircraft had been certified for overwater operations. In 2014, the FAA issued its final regulations governing pilot rest periods and work hours for all airlines certificated under Part 121 of the Federal Aviation Regulations. The rule, known as FAR 117 which became effective on January 4, 2014, impacts the required amount and timing of rest periods for pilots between work assignments, and modifies duty and rest requirements based on the time of day, number of scheduled segments, flight types, time zones and other factors. FAR 117 has resulted in increased pilot costs as we were required to hire more pilots in order to comply with the regulations. We believe we hold all necessary operating and airworthiness authorizations, certificates and licenses and are operating in compliance with applicable DOT and FAA regulations, interpretations and policies.

International Regulation

All international service is subject to the regulatory requirements of the foreign government involved. We currently operate international service to Aruba, Colombia, Costa Rica, Dominican Republic, El Salvador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Peru and St. Maarten, as well as Puerto Rico and the U.S. Virgin Islands. If we decide to increase our routes to additional international destinations, we will be required to obtain necessary authority from the DOT and the applicable foreign government. We are also required to comply with overfly regulations in countries that lay along our routes but which we do not serve.

International service is also subject to Customs and Border Protection, or CBP, immigration and agriculture requirements and the requirements of equivalent foreign governmental agencies. Like other airlines flying international routes, from time to time we may be subject to civil fines and penalties imposed by CBP if unmanifested or illegal cargo, such as illegal narcotics, is found on our aircraft. These fines and penalties, which in the case of narcotics are based upon the retail value of the seizure, may be substantial. We have implemented a comprehensive security program at our airports to reduce the risk of illegal cargo being placed on our aircraft, and we seek to cooperate actively with CBP and other U.S. and foreign law enforcement agencies in investigating incidents or attempts to introduce illegal cargo.

Security Regulation

The TSA was created in 2001 with the responsibility and authority to oversee the implementation, and ensure the adequacy of security measures at airports and other transportation facilities. Funding for passenger security is provided in part by a per enplanement ticket tax (passenger security fee). Prior to and for the first half of 2014, this fee was $2.50 per passenger flight segment, subject to a maximum of $5 per one-way trip. Effective July 1, 2014, the security fee was set at a flat rate of $5.60 each way. On December 19, 2014, a new law took effect which limits a round-trip fee to $11.20. We cannot forecast what additional security and safety requirements may be imposed in the future or the costs or revenue impact that would be associated with complying with such requirements. In addition, in the past, the TSA has assessed an Aviation Security Infrastructure Fee, or ASIF, on each airline. This fee was eliminated by the TSA effective October 1, 2014.

Environmental Regulation

We are subject to various federal, state and local laws and regulations relating to the protection of the environment and affecting matters such as aircraft engine emissions, aircraft noise emissions and the discharge or disposal of materials and chemicals, which laws and regulations are administered by numerous state and federal agencies. The Environmental Protection Agency, or EPA, regulates operations, including air carrier operations, which affect the quality of air in the United States. We believe the aircraft in our fleet meet all emission standards issued by the EPA. Concern about climate change and greenhouse gases may result in additional regulation or taxation of aircraft emissions in the United States and abroad.

Federal law recognizes the right of airport operators with special noise problems to implement local noise abatement procedures so long as those procedures do not interfere unreasonably with interstate and foreign commerce and the national air transportation system. These restrictions can include limiting nighttime operations, directing specific aircraft operational procedures during takeoff and initial climb, and limiting the overall number of flights at an airport.

Other Regulations

We are subject to certain provisions of the Communications Act of 1934, as amended, and are required to obtain an aeronautical radio license from the Federal Communications Commission, or FCC. To the extent we are subject to FCC requirements, we will take all necessary steps to comply with those requirements. We are also subject to state and local laws and regulations at locations where we operate and the regulations of various local authorities that operate the airports we serve.

Future Regulations

The U.S. and foreign governments may consider and adopt new laws, regulations, interpretations and policies regarding a wide variety of matters that could directly or indirectly affect our results of operations. We cannot predict what laws, regulations, interpretations and policies might be considered in the future, nor can we judge what impact, if any, the implementation of any of these proposals or changes might have on our business.

ITEM 1A. RISK FACTORS

Cautionary Statement Regarding Forward-Looking Statements

This Annual Report on Form 10-K contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the Securities Act), and Section 21E of the Securities Exchange Act of 1934, as amended (the Exchange Act) which are subject to the “safe harbor” created by those sections. Forward-looking statements are based on our management’s beliefs and assumptions and on information currently available to our management. All statements other than statements of historical facts are “forward-looking statements” for purposes of these provisions. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “could,” “would,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “project,” “predict,” “potential,” and similar expressions intended to identify forward-looking statements. Such forward-looking statements are subject to risks, uncertainties and other important factors that could cause actual results and the timing of certain events to differ materially from future results expressed or implied by such forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those identified below. Furthermore, such forward-looking statements speak only as of the date of this report. Except as required by law, we undertake no obligation to update any forward-looking statements to reflect events or circumstances after the date of such statements. Additional risks or uncertainties (i) that are not currently known to us, (ii) that we currently deem to be immaterial, or (iii) that could apply to any company, could also materially adversely affect our business, financial condition, or future results. You should carefully consider the risks described below and the other information in this report. If any of the following risks materialize, our business could be materially harmed, and our financial condition and results of operations could be materially and adversely affected. References in this report to “Spirit,” “we,” “us,” “our,” or the “Company” shall mean Spirit Airlines, Inc., unless the context indicates otherwise.

Risks Related to Our Industry

We operate in an extremely competitive industry.

We face significant competition with respect to routes, fares and services. Within the airline industry, we compete with traditional network airlines, other low-cost airlines and regional airlines on many of our routes. Competition in most of the destinations we presently serve is intense, due to the large number of carriers in those markets. Furthermore, other airlines may begin service or increase existing service on routes where we currently face little competition. Most of our competitors are larger than us and have significantly greater financial and other resources than we do.

The airline industry is particularly susceptible to price discounting because once a flight is scheduled, airlines incur only nominal additional costs to provide service to passengers occupying otherwise unsold seats. Increased fare or other price competition has, and may continue to, adversely affect our operations. Moreover, many other airlines have begun to unbundle services by charging separately for services such as baggage and advance seat selection. This unbundling and other cost reducing measures could enable competitor airlines to reduce fares on routes that we serve. In 2015, the availability of low priced fares coupled with an increase in domestic capacity led to dramatic changes in pricing behavior in many U.S. markets. Many domestic carriers began matching lower cost airline pricing, either with limited or unlimited inventory.

Airlines increase or decrease capacity in markets based on perceived profitability, market share objectives, competitive considerations and other reasons. Decisions by our competitors that increase overall industry capacity, or capacity dedicated to a particular domestic or foreign region, market or route, could have a material adverse impact on our business. If a traditional network airline were to successfully develop a low-cost structure, compete with us on price or if we were to experience increased competition from other low-cost carriers, our business could be materially adversely affected.

Many of the traditional network airlines in the United States. have on one or more occasions initiated bankruptcy proceedings in attempts to restructure their debt and other obligations and reduce their operating costs. They also have completed large mergers that have increased their scale and share of the travel market. On November 29, 2011, AMR Corporation and substantially all of its subsidiaries, including American Airlines, Inc., filed a petition for relief under Chapter 11 of the U.S. Bankruptcy Code. In December 2013, AMR Corporation and US Airways Group, Inc. completed a merger and formally became American Airlines Group Inc. We presently compete with American Airlines in a majority of our markets. This merger along with earlier mergers between Delta Airlines and Northwest Airlines, between United Airlines and Continental Airlines, and Southwest Airlines and AirTran Airways, have created four very large and powerful network airlines, which creates a challenging pricing environment for smaller airlines like us.

Our growth and the success of our ULCC business model could stimulate competition in our markets through our competitors’ development of their own ULCC strategies, new pricing policies designed to compete with ULCCs or new market entrants. Any such competitor may have greater financial resources and access to less expensive sources of capital than we do, which could enable them to operate their business with a lower cost structure, or enable them to operate with lower-marginal revenues without substantial adverse effects, than we can. If these competitors adopt and successfully execute a ULCC business model, we could be materially adversely affected. In 2015, Delta Airlines began to market and sell a "Basic Economy" fare which was designed in part to provide its customers with a low base fare similar to Spirit. Other major carriers have announced plans to market similar discounted fare classes.

There has been significant consolidation within the airline industry including, for example, the combinations of American Airlines and US Airways, Delta Air Lines and Northwest Airlines, United Airlines and Continental Airlines and Southwest Airlines and AirTran Airways. In the future, there may be additional consolidation in our industry. Any business combination could significantly alter industry conditions and competition within the airline industry, which could have an adverse effect on our business.

The extremely competitive nature of the airline industry could prevent us from attaining the level of passenger traffic or maintaining the level of fares or revenues related to ancillary services required to sustain profitable operations in new and existing markets and could impede our growth strategy, which could harm our operating results. Due to our relatively small size, we are susceptible to a fare war or other competitive activities in one or more of the markets we serve, which could have a material adverse effect on our business, results of operations and financial condition.

Our low cost structure is one of our primary competitive advantages, and many factors could affect our ability to control our costs.

Our low cost structure is one of our primary competitive advantages. However, we have limited control over many of our costs. For example, we have limited control over the price and availability of aircraft fuel, aviation insurance, airport costs and related infrastructure taxes, the cost of meeting changing regulatory requirements and our cost to access capital or financing. In addition, the compensation and benefit costs applicable to a significant portion of our employees are established by the terms of our collective bargaining agreements. We cannot guarantee we will be able to maintain a cost advantage over our competitors. If our cost structure increases and we are no longer able to maintain a sufficient cost advantage over our competitors, it could have a material adverse effect on our business, results of operations and financial condition.

The airline industry is heavily influenced by the price and availability of aircraft fuel. Continued volatility in fuel costs or significant disruptions in the supply of fuel, including hurricanes and other events affecting the Gulf Coast in particular, could materially adversely affect our business, results of operations and financial condition.

Aircraft fuel costs represent our single largest operating cost, accounting for 28.3%, 38.9% and 40.2% of our total operating expenses for 2015, 2014 and 2013, respectively. As such, our operating results are significantly affected by changes in the availability and the cost of aircraft fuel, especially aircraft fuel refined in the U.S. Gulf Coast region, on which we are highly dependent. Both the cost and the availability of aircraft fuel are subject to many meteorological, economic and political factors and events occurring throughout the world, which we can neither control nor accurately predict. For example, a major hurricane making landfall along the Gulf Coast could cause disruption to oil production, refinery operations and pipeline capacity in that region, possibly resulting in significant increases in the price of aircraft fuel and diminished availability of aircraft fuel supply. Any disruption to oil production, refinery operations, or pipeline capacity in the Gulf Coast region could have a disproportionate impact on our operating results compared to other airlines that have more diversified fuel sources. Fuel prices also may be affected by geopolitical and macroeconomic conditions and events that are outside of our control. Instability within major oil producing regions, such as the Middle East, changes in demand from major petroleum users such as China, and secular increases in competing energy sources are examples of these trends.

Aircraft fuel prices have been subject to high volatility, fluctuating substantially over the past several years. For example, our fuel prices spiked at a high of $3.32 per gallon, in the second quarter of 2012, and have recently fallen as low as $1.57 per gallon in the fourth quarter of 2015. We can not predict whether oil prices will remain at current low prices or for how long. Due to the large proportion of aircraft fuel costs in our total operating cost base, even a relatively small increase or decrease in the price of aircraft fuel can have a significant negative impact on our operating costs or revenues and on our business, results of operations and financial condition.

Our fuel derivative activity, if any, may not reduce our fuel costs.

From time to time, we may enter into fuel derivative contracts in order to mitigate the risk to our business from future volatility in fuel prices. Our derivatives may generally consist of United States Gulf Coast jet fuel swaps (jet fuel swaps) and United States Gulf Coast jet fuel options (jet fuel options). Both jet fuel swaps and jet fuel options can be used at times to

protect the refining risk between the price of crude oil and the price of refined jet fuel, and to manage the risk of increasing fuel prices. As of December 31, 2015, we had no outstanding jet fuel derivatives. There can be no assurance that we will be able to enter into fuel derivative contracts in the future if we are required or choose to do so. Our liquidity and general level of capital resources impacts our ability to hedge our fuel requirements. Even if we are able to hedge portions of our future fuel requirements, we cannot guarantee that our derivative contracts will provide sufficient protection against increased fuel costs or that our counterparties will be able to perform under our derivative contracts, such as in the case of a counterparty’s insolvency. Furthermore, our ability to react to the cost of fuel, absent hedging, is limited because we set the price of tickets in advance of incurring fuel costs. Our ability to pass on any significant increases in aircraft fuel costs through fare increases could also be limited. In the event of a reduction in fuel prices compared to our hedged position, if any, our hedged positions could counteract the cost benefit of lower fuel prices and may require us to post cash margin collateral. Please see “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Trends and Uncertainties Affecting Our Business—Aircraft Fuel.”

Restrictions on or increased taxes applicable to charges for ancillary products and services paid by airline passengers and burdensome consumer protection regulations or laws could harm our business, results of operations and financial condition.

During 2015, 2014 and 2013, we generated non-ticket revenues of $972.1 million, $786.6 million and $668.4 million, respectively. Our non-ticket revenues are generated from charges for, among other things, baggage, bookings through certain of our distribution channels, advance seat selection, itinerary changes and loyalty programs. The DOT has rules governing many facets of the airline-consumer relationship, including, for instance, price advertising, tarmac delays, bumping of passengers from flights, ticket refunds and the carriage of disabled passengers. If we are not able to remain in compliance with these rules, the DOT may subject us to fines or other enforcement action, including requirements to modify our passenger reservations system, which could have a material adverse effect on our business. The U.S. Congress and Federal administrative agencies have investigated the increasingly common airline industry practice of unbundling the pricing of certain products and services. If new taxes are imposed on non-ticket revenues, or if other laws or regulations are adopted that make unbundling of airline products and services impermissible, or more cumbersome or expensive, our business, results of operations and financial condition could be harmed. Congressional and other government scrutiny may also change industry practice or public willingness to pay for ancillary services. See also “—We are subject to extensive regulation by the Federal Aviation Administration, the Department of Transportation and other U.S. and foreign governmental agencies, compliance with which could cause us to incur increased costs and adversely affect our business and financial results.”

The airline industry is particularly sensitive to changes in economic conditions. Adverse economic conditions would negatively impact our business, results of operations and financial condition.

Our business and the airline industry in general are affected by many changing economic conditions beyond our control, including, among others:


•	changes and volatility in general economic conditions, including the severity and duration of any downturn in the U.S. or global economy and financial markets;


•	changes in consumer preferences, perceptions, spending patterns or demographic trends, including any increased preference for higher-fare carriers offering higher amenity levels, and reduced preferences for low-fare carriers offering more basic transportation, during better economic times;


•	higher levels of unemployment and varying levels of disposable or discretionary income;


•	depressed housing and stock market prices; and


•	lower levels of actual or perceived consumer confidence.

These factors can adversely affect, and from time to time have adversely affected, our results of operations, our ability to obtain financing on acceptable terms and our liquidity. Unfavorable general economic conditions, such as higher unemployment rates, a constrained credit market, housing-related pressures and increased focus on reducing business operating costs can reduce spending for price-sensitive leisure and business travel. For many travelers, in particular the price-sensitive travelers we serve, air transportation is a discretionary purchase that they may reduce or eliminate from their spending in difficult economic times. The overall decrease in demand for air transportation in the United States in 2008 and 2009 resulting from record high fuel prices and the economic recession required us to take significant steps to reduce our capacity, which reduced our revenues. Unfavorable economic conditions could also affect our ability to raise prices to counteract increased fuel, labor or other costs, resulting in a material adverse effect on our business, results of operations and financial condition.

The airline industry faces ongoing security concerns and related cost burdens, furthered by threatened or actual terrorist attacks or other hostilities that could significantly harm our industry and our business.

The terrorist attacks of September 11, 2001 and their aftermath negatively affected the airline industry. The primary effects experienced by the airline industry included:


•	substantial loss of revenue and flight disruption costs caused by the grounding of all commercial air traffic in or headed to the United States by the FAA for three days after the terrorist attacks;


•	increased security and insurance costs;


•	increased concerns about future terrorist attacks;


•	airport shutdowns and flight cancellations and delays due to security breaches and perceived safety threats; and


•	significantly reduced passenger traffic and yields due to the subsequent dramatic drop in demand for air travel.

Since September 11, 2001, the Department of Homeland Security and the TSA have implemented numerous security measures that restrict airline operations and increase costs, and are likely to implement additional measures in the future. For example, following the widely publicized attempt of an alleged terrorist to detonate plastic explosives hidden underneath his clothes on a Northwest Airlines flight on Christmas Day in 2009, passengers became subject to enhanced random screening, which included pat-downs, explosive detection testing and body scans. Enhanced passenger screening, increased regulation governing carry-on baggage and other similar restrictions on passenger travel may further increase passenger inconvenience and reduce the demand for air travel. In addition, increased or enhanced security measures have tended to result in higher governmental fees imposed on airlines, resulting in higher operating costs for airlines, which we may not be able to pass on to consumers in the form of higher prices. Any future terrorist attacks or attempted attacks, even if not made directly on the airline industry, or the fear of such attacks or other hostilities (including elevated national threat warnings or selective cancellation or redirection of flights due to terror threats) would likely have a material adverse effect on our business, results of operations and financial condition and on the airline industry in general.

Airlines are often affected by factors beyond their control including: air traffic congestion at airports; air traffic control inefficiencies; adverse weather conditions, such as hurricanes or blizzards; increased security measures; new travel related taxes or the outbreak of disease, any of which could harm our business, operating results and financial condition.

Like other airlines, our business is affected by factors beyond our control, including air traffic congestion at airports, air traffic control inefficiencies, adverse weather conditions, increased security measures, new travel related taxes and the outbreak of disease. Factors that cause flight delays frustrate passengers and increase costs, which in turn could adversely affect profitability. The federal government singularly controls all U.S. airspace, and airlines are completely dependent on the FAA to operate that airspace in a safe, efficient and affordable manner. The air traffic control system, which is operated by the FAA, faces challenges in managing the growing demand for U.S. air travel. U.S. and foreign air-traffic controllers often rely on outdated technologies that routinely overwhelm the system and compel airlines to fly inefficient, indirect routes resulting in delays. Adverse weather conditions and natural disasters, such as hurricanes affecting southern Florida and the Caribbean as well as other areas of the eastern United States (such as Hurricane Sandy in October 2012), winter snowstorms or the January 2010 earthquakes in Port-au-Prince, Haiti, can cause flight cancellations or significant delays. For example, during the second quarter of 2015, we experienced consecutive storm systems in Dallas, Chicago, New York and Detroit followed by Tropical Storm Bill that sat over Houston before moving north to Dallas. The timing and location of these storm systems produced a domino effect on our operations resulting in over 500 flight cancellations and numerous flight delays, which resulted in an adverse effect on our results of operations. Cancellations or delays due to adverse weather conditions or natural disasters, air traffic control problems or inefficiencies, breaches in security or other factors may affect us to a greater degree than other, larger airlines that may be able to recover more quickly from these events, and therefore could harm our business, results of operations and financial condition to a greater degree than other air carriers. Because of our high utilization, point-to-point network, operational disruptions can have a disproportionate impact on our ability to recover. In addition, many airlines reaccommodate their disrupted passengers on other airlines at prearranged rates under flight interruption manifest agreements. We have been unsuccessful in procuring any of these agreements with our peers, which makes our recovery from disruption more challenging than for larger airlines that have these agreements in place. Similarly, outbreaks of pandemic or contagious diseases, such as ebola, measles, avian flu, severe acute respiratory syndrome (SARS), H1N1 (swine) flu and Zika virus, could result in significant decreases in passenger traffic and the imposition of government restrictions in service and could have a material adverse impact on the airline industry. Increased travel taxes, such as those provided in the Travel Promotion Act, enacted March 10, 2010, which charges visitors from certain countries a $10 fee every two years to travel into the United States

to subsidize certain travel promotion efforts, could also result in decreases in passenger traffic. Any general reduction in airline passenger traffic could have a material adverse effect on our business, results of operations and financial condition.

Restrictions on or litigation regarding third-party membership discount programs could harm our business, operating results and financial condition.

We generate a relatively small but growing portion of our revenue from order referral fees, revenue share and other fees paid to us by third-party merchants for customer click-throughs, distribution of third-party promotional materials and referrals arising from products and services of the third-party merchants that we offer to our customers on our website. Some of these third-party referral-based offers are for memberships in discount programs or similar promotions made to customers who have purchased products from us, and for which we receive a payment from the third-party merchants for every customer that accepts the promotion. Certain of these third-party membership discount programs have been the subject of consumer complaints, litigation and regulatory actions alleging that the enrollment and billing practices involved in the programs violate various consumer protection laws or are otherwise deceptive. Any private or governmental claim or action that may be brought against us in the future relating to these third-party membership programs could result in our being obligated to pay damages or incurring legal fees in defending claims. These damages and fees could be disproportionate to the revenues we generate through these relationships. In addition, customer dissatisfaction or a significant reduction in or termination of the third-party membership discount offers on our website as a result of these claims could have a negative impact on our brand, and have a material adverse effect on our business, results of operations and financial condition.

We face competition from air travel substitutes.

In addition to airline competition from traditional network airlines, other low-cost airlines and regional airlines, we also face competition from air travel substitutes. On our domestic routes, we face competition from some other transportation alternatives, such as bus, train or automobile. In addition, technology advancements may limit the demand for air travel. For example, video teleconferencing and other methods of electronic communication may reduce the need for in-person communication and add a new dimension of competition to the industry as travelers seek lower-cost substitutes for air travel. If we are unable to adjust rapidly in the event the basis of competition in our markets changes, it could have a material adverse effect on our business, results of operations and financial condition.

Risks Related to Our Business

Increased labor costs, union disputes, employee strikes and other labor-related disruption may adversely affect our business, results of operations and financial conditions.

Our business is labor intensive, with labor costs representing approximately 23.2%, 19.9% and 19.1% of our total operating costs for 2015, 2014 and 2013, respectively. As of December 31, 2015, approximately 73% of our workforce was represented by labor unions. We cannot assure you that our labor costs going forward will remain competitive because in the future our labor agreements may be amended or become amendable and new agreements could have terms with higher labor costs; one or more of our competitors may significantly reduce their labor costs, thereby reducing or eliminating our comparative advantages as to one or more of such competitors; or our labor costs may increase in connection with our growth. We may also become subject to additional collective bargaining agreements in the future as non-unionized workers may unionize.

Relations between air carriers and labor unions in the United States are governed by the Railway Labor Act, or the RLA. Under the RLA, collective bargaining agreements generally contain “amendable dates” rather than expiration dates, and the RLA requires that a carrier maintain the existing terms and conditions of employment following the amendable date through a multi-stage and usually lengthy series of bargaining processes overseen by the NMB. This process continues until either the parties have reached agreement on a new collective bargaining agreement, or the parties have been released to “self-help” by the NMB. In most circumstances, the RLA prohibits strikes; however, after release by the NMB, carriers and unions are free to engage in self-help measures such as lockouts and strikes.

Our flight operations were shut down due to a strike by our pilots beginning on June 12, 2010 and lasting until we and the union representing our pilots reached a tentative agreement for a new contract. Under a Return to Work Agreement, we began to resume flights on June 17, 2010 and resumed our full flight schedule on June 18, 2010. On August 1, 2010, we and the pilots’ union executed a five-year collective bargaining agreement. This shutdown had a material adverse effect on our results of operations for 2010.

We entered into a five-year agreement with our flight dispatchers in August 2013. In August 2014, under the supervision of the NMB, we reached a tentative agreement for a five-year contract with our flight attendants. The tentative agreement was subject to ratification by the flight attendant membership. On October 1, 2014, we were notified that the flight attendants voted

not to ratify the tentative agreement. We will continue to work with the AFA-CWA and the NMB towards a goal of reaching a mutually beneficial agreement.

In July 2014, certain ramp service agents directly employed by us voted to be represented by the International Association of Machinists and Aerospace Workers (IAMAW). In May 2015, we entered into a five-year interim collective bargaining agreement with the IAMAW, including material economic terms, and we are continuing the process of negotiating a final collective bargaining agreement with the IAMAW. As of December 31, 2015, these ramp service agents served 1 of the 56 airports where we operate. In August 2015, our collective bargaining agreement with our pilot union ALPA became amendable, and we are currently in discussions with ALPA on a new contract. If we are unable to reach agreement with any of our unionized work groups in current or future negotiations regarding the terms of their collective bargaining agreements, we may be subject to work interruptions or stoppages. Any such action or other labor dispute with unionized employees could disrupt our operations, reduce our profitability, or interfere with the ability of our management to focus on executing our business strategies.

The Patient Protection and Affordable Care Act was enacted in 2010, and we expect it will continue to evolve. It could significantly increase cost of the healthcare benefits provided to our U.S. employees. In addition, the failure to comply materially with such existing and new laws, rules and regulations could adversely affect our business, results of operations and financial conditions.

We have a significant amount of aircraft-related fixed obligations that could impair our liquidity and thereby harm our business, results of operations and financial condition.

The airline business is capital intensive and, as a result, many airline companies are highly leveraged. As of December 31, 2015, our 79 aircraft fleet consisted of 61 aircraft financed under operating leases and 18 aircraft financed under debt arrangements. In 2015 and 2014, we paid the lessors rent of $217.0 million and $198.7 million, respectively, and paid maintenance deposits of $59.2 million and $58.5 million, respectively. As of December 31, 2015, we had future operating lease obligations of approximately $1.6 billion. In 2015, we made scheduled principal payments of $25.4 million on outstanding debt obligations. In 2014, we had no payments related to debt arrangements as we entered into these arrangements in late 2014 and repayment commenced in 2015. As of December 31, 2015, we had future principal debt obligations of $659.3 million, of which $51.5 million is due in 2016. In addition, we have significant obligations for aircraft and spare engines that we have ordered from Airbus, International Aero Engines AG, or IAE, and Pratt and Whitney for delivery over the next several years. Our ability to pay the fixed costs associated with our contractual obligations will depend on our operating performance, cash flow and our ability to secure adequate financing, which will in turn depend on, among other things, the success of our current business strategy, fuel price volatility, weakening or improvement in the U.S. economy, as well as general economic and political conditions and other factors that are beyond our control. The amount of our aircraft related fixed obligations and related need to obtain financing could have a material adverse effect on our business, results of operations and financial condition and could:


•	require a substantial portion of cash flow from operations for operating lease and maintenance deposit payments, thereby reducing the availability of our cash flow to fund working capital, capital expenditures and other general corporate purposes;


•	limit our ability to make required pre-delivery deposit payments, or PDPs, including those payable to our aircraft and engine manufacturers for our aircraft and spare engines on order;


•	limit our ability to obtain additional financing to support our expansion plans and for working capital and other purposes on acceptable terms or at all;


•	make it more difficult for us to pay our other obligations as they become due during adverse general economic and market industry conditions because any related decrease in revenues could cause us to not have sufficient cash flows from operations to make our scheduled payments;


•	reduce our flexibility in planning for, or reacting to, changes in our business and the airline industry and, consequently, place us at a competitive disadvantage to our competitors with fewer fixed payment obligations; and


•	cause us to lose access to one or more aircraft and forfeit our rent deposits if we are unable to make our required aircraft lease rental and debt payments and our lessors or lenders exercise their remedies under the lease and debt agreements including cross default provisions in certain of our leases and mortgages.

A failure to pay our operating lease, debt and other fixed cost obligations or a breach of our contractual obligations could result in a variety of adverse consequences, including the exercise of remedies by our creditors and lessors. In such a situation, it is unlikely that we would be able to cure our breach, fulfill our obligations, make required lease or debt payments or

otherwise cover our fixed costs, which would have a material adverse effect on our business, results of operations and financial condition.

We are highly dependent upon our cash balances and operating cash flows.

As of December 31, 2015, we had access to lines of credit from our four physical fuel delivery and derivative counterparties and our purchase credit card issuer aggregating $56.6 million. In addition, we had a $25.1 million unsecured standby letter of credit facility. These credit facilities are not adequate to finance our operations, and we will continue to be dependent on our operating cash flows and cash balances to fund our operations and to make scheduled payments on our aircraft related fixed obligations. In addition, our credit card processors are entitled to withhold receipts from customer purchases from us, under certain circumstances. Although our credit card processors currently do not have a right to hold back credit card receipts to cover repayment to customers, if we fail to maintain certain liquidity and other financial covenants, their rights to holdback would be reinstated, which would result in a reduction of unrestricted cash that could be material. In addition, we are required by some of our aircraft lessors to fund reserves in cash in advance for scheduled maintenance, and a portion of our cash is therefore unavailable until after we have completed the scheduled maintenance in accordance with the terms of the operating leases. Based on the age of our fleet and our growth strategy, these maintenance deposits will increase over the next few years before we receive any significant reimbursement for completed maintenance. If we fail to generate sufficient funds from operations to meet our operating cash requirements or do not obtain a line of credit, other borrowing facility or equity financing, we could default on our operating lease and fixed obligations. Our inability to meet our obligations as they become due would have a material adverse effect on our business, results of operations and financial condition.

A deterioration in worldwide economic conditions may adversely affect our business, operating results, financial condition, liquidity and ability to obtain financing or access capital markets.

The general worldwide economy has in the past experienced downturns due to the effects of the European debt crisis, unfavorable U.S. economic conditions and slowing growth in certain Asian economies, including general credit market crises, collateral effects on the finance and banking industries, energy price volatility, concerns about inflation, slower economic activity, decreased consumer confidence, reduced corporate profits and capital spending, adverse business conditions, geopolitical conflict and liquidity concerns. The airline industry is particularly sensitive to changes in economic conditions, which affect customer travel patterns and related revenues. A weak economy could reduce our bookings, and a reduction in discretionary spending could also decrease amounts our customers are willing to pay. Unfavorable economic conditions can also impact the ability of airlines to raise fares to help offset increased fuel, labor and other costs. We cannot accurately predict the effect or duration of any economic slowdown or the timing or strength of a subsequent economic recovery.

In addition, we have significant obligations for aircraft and spare engines that we have ordered from Airbus, IAE and Pratt and Whitney over the next several years, and we will need to finance these purchases. We may not have sufficient liquidity or creditworthiness to fund the purchase of aircraft and engines, including payment of PDPs, or for other working capital. Factors that affect our ability to raise financing or access the capital markets include market conditions in the airline industry, economic conditions, the perceived residual value of aircraft and related assets, the level and volatility of our earnings, our relative competitive position in the markets in which we operate, our ability to retain key personnel, our operating cash flows and legal and regulatory developments. Regardless of our creditworthiness, at times the market for aircraft purchase or lease financing has been very constrained due to such factors as the general state of the capital markets and the financial position of the major providers of commercial aircraft financing.

Our liquidity and general level of capital resources impact our ability to hedge our fuel requirements.

From time to time, we may enter into fuel derivative contracts in order to mitigate the risk to our business from future volatility in fuel prices, refining risk between the price of crude oil and the price of refined jet fuel, and to manage the risk of increasing fuel prices. As of December 31, 2015, we had no outstanding jet fuel derivatives. There can be no assurance that we will be able to enter into fuel derivative contracts in the future if we are required or choose to do so. In the past, we have not had and in the future we may not have sufficient creditworthiness or liquidity to post the collateral necessary to hedge our fuel requirements. Even if we are able to hedge portions of our future fuel requirements, we cannot guarantee that our derivative contracts will provide any particular level of protection against increased fuel costs or that our counterparties will be able to perform under our derivative contracts, such as in the case of a counterparty’s insolvency. In a falling fuel environment, we may be required to make cash payments to our counterparties which may impair our liquidity position and increase our costs. Furthermore, our ability to react to the cost of fuel, absent hedging, is limited, because we set the price of tickets in advance of knowing our fuel costs at the time the tickets are flown. Our ability to pass on any significant increases in aircraft fuel costs through fare increases could also be limited.

We rely on maintaining a high daily aircraft utilization rate to implement our low cost structure, which makes us especially vulnerable to flight delays or cancellations or aircraft unavailability.

We maintain a high daily aircraft utilization rate. Our average daily aircraft utilization was 12.7 hours for 2015, 2014 and 2013. Aircraft utilization is the average amount of time per day that our aircraft spend carrying passengers. Our revenue per aircraft can be increased by high daily aircraft utilization, which is achieved in part by reducing turnaround times at airports so we can fly more hours on average in a day. Aircraft utilization is reduced by delays and cancellations from various factors, many of which are beyond our control, including air traffic congestion at airports or other air traffic control problems, adverse weather conditions, increased security measures or breaches in security, international or domestic conflicts, terrorist activity, or other changes in business conditions. A significant portion of our operations are concentrated in markets such as South Florida, the Caribbean, Latin America and the Northeast and northern Midwest regions of the United States, which are particularly vulnerable to weather, airport traffic constraints and other delays. In addition, pulling aircraft out of service for unscheduled and scheduled maintenance, the occurrence of which will increase as our fleet ages, may materially reduce our average fleet utilization and require that we seek short-term substitute capacity at increased costs. Due to the relatively small size of our fleet and high daily aircraft utilization rate, the unavailability of one or more aircraft and resulting reduced capacity could have a material adverse effect on our business, results of operations and financial condition.

Our maintenance costs will increase as our fleet ages, and we will periodically incur substantial maintenance costs due to the maintenance schedules of our aircraft fleet.

As of December 31, 2015, the average age of our aircraft was approximately 5.2 years. Our relatively new aircraft require less maintenance now than they will in the future. Our fleet will require more maintenance as it ages and our maintenance and repair expenses for each of our aircraft will be incurred at approximately the same intervals. For our leased aircraft, we expect that the final heavy maintenance events will be amortized over the remaining lease term rather than until the next estimated heavy maintenance event, because we account for heavy maintenance under the deferral method. This will result in significantly higher depreciation and amortization expense related to heavy maintenance in the last few years of the leases as compared to the costs in earlier periods. Moreover, because our current fleet was acquired over a relatively short period, significant maintenance that is scheduled on each of these planes is occurring at roughly the same time, meaning we will incur our most expensive scheduled maintenance obligations, known as heavy maintenance, across our present fleet around the same time. These more significant maintenance activities result in out-of-service periods during which our aircraft are dedicated to maintenance activities and unavailable to fly revenue service. In addition, the terms of some of our lease agreements require us to pay maintenance reserves to the lessor in advance of the performance of major maintenance, resulting in our recording significant prepaid deposits on our balance sheet. Depending on their recoverability, these maintenance reserves may be classified as supplemental rent. We expect scheduled and unscheduled aircraft maintenance expenses to increase as a percentage of our revenue over the next several years. Any significant increase in maintenance and repair expenses would have a material adverse effect on our business, results of operations and financial condition. Please see “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Critical Accounting Policies and Estimates—Aircraft Maintenance, Materials and Repair Costs and Heavy Maintenance Amortization” and “—Maintenance Reserves.”

Our lack of marketing alliances could harm our business.

Many airlines, including the domestic traditional network airlines (American, Delta and United) have marketing alliances with other airlines, under which they market and advertise their status as marketing alliance partners. These alliances, such as OneWorld, SkyTeam and Star Alliance, generally provide for code-sharing, frequent flier program reciprocity, coordinated scheduling of flights to permit convenient connections and other joint marketing activities. Such arrangements permit an airline to market flights operated by other alliance members as its own. This increases the destinations, connections and frequencies offered by the airline and provides an opportunity to increase traffic on that airline’s segment of flights connecting with alliance partners. We currently do not have any alliances with U.S. or foreign airlines. Our lack of marketing alliances puts us at a competitive disadvantage to traditional network carriers who are able to attract passengers through more widespread alliances, particularly on international routes, and that disadvantage may result in a material adverse effect on our passenger traffic, business, results of operations and financial condition.

We are subject to extensive and increasing regulation by the FAA, DOT, TSA and other U.S. and foreign governmental agencies, compliance with which could cause us to incur increased costs and adversely affect our business and financial results.

Airlines are subject to extensive and increasing regulatory and legal compliance requirements, both domestically and internationally, that involve significant costs. In the last several years, Congress has passed laws, and the DOT, FAA and TSA have issued regulations, relating to the operation of airlines that have required significant expenditures. We expect to continue to incur expenses in connection with complying with government regulations. Additional laws, regulations, taxes and increased airport rates and charges have been proposed from time to time that could significantly increase the cost of airline operations or reduce the demand for air travel. If adopted, these measures could have the effect of raising ticket prices, reducing revenue and increasing costs. For example, the DOT finalized rules in April 2010 requiring new procedures for customer handling during

long onboard tarmac delays, as well as additional reporting requirements for airlines that could increase the cost of airline operations or reduce revenues. The DOT has been aggressively investigating alleged violations of these rules. A second set of DOT final rules, which became effective in August 2011 and January 2012, addresses, among other things, concerns about how airlines handle interactions with passengers through advertising, the reservations process, at the airport and on board the aircraft, including requirements for disclosure of base fares plus a set of regulatorily dictated options and limits on cancellations and service charges for changes and cancellations. Additional consumer passenger rules were proposed in 2014 which may be implemented in 2016 and additional disability rules may be proposed in 2016. In addition, during 2014, the FAA issued its final regulations governing pilot rest periods and work hours for all airlines certificated under Part 121 of the Federal Aviation Regulations. The rule known as FAR 117, which became effective January 4, 2014, impacts the required amount and timing of rest periods for pilots between work assignments and modifies duty and rest requirements based on the time of day, number of scheduled segments, flight types, time zones and other factors. Compliance with these rules may increase our costs, while failure to remain in full compliance with these rules may subject us to fines or other enforcement action.

In August 2010, the Airline Baggage Transparency and Accountability Act was introduced in the United States Senate. This legislation, as proposed, would have increase disclosure regarding fees for airline ticket sales, impose federal taxes on charges for carry-on and checked baggage, authorize the DOT's Aviation Consumer Protection Division to oversee lost and stolen baggage claims, and require data collection and the public release of collected data concerning airline handling of lost, damaged and stolen luggage. In early 2011, the United States Senate passed an amendment to the FAA reauthorization bill that, if enacted, would have imposed federal taxes at a rate of 7.5% on charges for carry-on baggage. Currently, there have been no updates regarding such legislation. However, in the event the Airline Baggage Transparency and Accountability Act, the Senate amendment to the FAA reauthorization bill or similar legislation were to be enacted, it is uncertain what effect it would have on our results of operations and financial condition.

We cannot assure you that these and other laws or regulations enacted in the future will not harm our business. In addition, the TSA mandates the federalization of certain airport security procedures and imposes additional security requirements on airports and airlines, most of which are funded by a per ticket tax on passengers and a tax on airlines. Prior to and for the first half of 2014, the passenger security fee was $2.50 per passenger flight segment, subject to a $5 per one-way trip cap. In July 2014, the TSA implemented an increased passenger security fee at a flat rate of $5.60. On December 19, 2014, a new law took effect which limits a round-trip fee to $11.20. We cannot forecast what additional security and safety requirements may be imposed in the future or the costs or revenue impact that would be associated with complying with such requirements.

Our ability to operate as an airline is dependent on our maintaining certifications issued to us by the DOT and the FAA. The FAA has the authority to issue mandatory orders relating to, among other things, the grounding of aircraft, inspection of aircraft, installation of new safety-related items and removal and replacement of aircraft parts that have failed or may fail in the future. A decision by the FAA to ground, or require time consuming inspections of or maintenance on, our aircraft, for any reason, could negatively affect our business and financial results. Federal law requires that air carriers operating large aircraft be continuously “fit, willing and able” to provide the services for which they are licensed. Our “fitness” is monitored by the DOT, which considers factors such as unfair or deceptive competition, advertising, baggage liability and disabled passenger transportation. While the DOT has seldom revoked a carrier's certification for lack of fitness, such an occurrence would render it impossible for us to continue operating as an airline. The DOT may also institute investigations or administrative proceedings against airlines for violations of regulations.

The U.S. government is under persistent pressure to implement cost cutting and efficiency initiatives. In addition, the U.S. government has recently and may in the future experience delays in the completion of its budget process which could delay funding for government departments and agencies that regulate or otherwise are tied to the aviation industry, including the DOT and FAA. To the extent that any such initiatives or budgeting delays affect the operations of these government departments and agencies, including by forcing mandatory furloughs of government employees, our operations and results of operations could be materially adversely effected.

International routes are regulated by treaties and related agreements between the United States and foreign governments. Our ability to operate international routes is subject to change because the applicable arrangements between the United States and foreign governments may be amended from time to time. Our access to new international markets may be limited by our ability to obtain the necessary certificates to fly the international routes. In addition, our operations in foreign countries are subject to regulation by foreign governments and our business may be affected by changes in law and future actions taken by such governments, including granting or withdrawal of government approvals and restrictions on competitive practices. We are subject to numerous foreign regulations based on the large number of countries outside the United States where we currently provide service. If we are not able to comply with this complex regulatory regime, our business could be significantly harmed. Please see “Business — Government Regulation.”

We may not be able to implement our growth strategy.

Our growth strategy includes acquiring additional aircraft, increasing the frequency of flights and size of aircraft used in markets we currently serve, and expanding the number of markets we serve where our low cost structure would likely be successful. Effectively implementing our growth strategy is critical for our business to achieve economies of scale and to sustain or increase our profitability. We face numerous challenges in implementing our growth strategy, including our ability to:


•	maintain profitability;


•	obtain financing to acquire new aircraft;


•	access airports located in our targeted geographic markets where we can operate routes in a manner that is consistent with our cost strategy;


•	gain access to international routes; and


•	access sufficient gates and other services at airports we currently serve or may seek to serve.

Our growth is dependent upon our ability to maintain a safe and secure operation and requires additional personnel, equipment and facilities. An inability to hire and retain personnel, timely secure the required equipment and facilities in a cost-effective manner, efficiently operate our expanded facilities or obtain the necessary regulatory approvals may adversely affect our ability to achieve our growth strategy, which could harm our business. In addition, expansion to new markets may have other risks due to factors specific to those markets. We may be unable to foresee all of the existing risks upon entering certain new markets or respond adequately to these risks, and our growth strategy and our business may suffer as a result. In addition, our competitors may reduce their fares and/or offer special promotions to deter our entry into a new market or to stop our growth into existing markets or new markets. We cannot assure you that we will be able to profitably expand our existing markets or establish new markets.

Some of our target growth markets in the Caribbean and Latin America include countries with less developed economies that may be vulnerable to unstable economic and political conditions, such as significant fluctuations in gross domestic product, interest and currency exchange rates, high inflation, civil disturbances, government instability, nationalization and expropriation of private assets and the imposition of taxes or other charges by governments. The occurrence of any of these events in markets served by us and the resulting instability may adversely affect our ability to implement our growth strategy.

In 2008, in response to record high fuel prices and rapidly deteriorating economic conditions, we modified our growth plans by terminating our leases for seven aircraft. We incurred significant expenses relating to our lease terminations, and have incurred additional expenses to acquire new aircraft in place of those under the terminated leases as we expanded our network. We may in the future determine to reduce further our future growth plans from previously announced levels, which may impact our business strategy and future profitability.

We rely heavily on technology and automated systems to operate our business and any failure of these technologies or systems or failure by their operators could harm our business.

We are highly dependent on technology and automated systems to operate our business and achieve low operating costs. These technologies and systems include our computerized airline reservation system, flight operations system, financial planning, management and accounting system, telecommunications systems, website, maintenance systems and check-in kiosks. The performance and reliability of our technology are critical to our ability to operate and compete effectively. Our Board of Directors recently approved a significant technology upgrade initiative meant to address our aging IT infrastructure. This initiative will upgrade, replace, and enhance multiple older and outdated legacy systems and hardware. The execution of our strategic plans could be negatively affected by (i) our ability to timely and effectively implement, transition, and maintain related information technology systems and infrastructure; (ii) our ability to effectively balance its investment of incremental operating expenses and capital expenditures related to its strategies against the need to effectively control cost; and (iii) our dependence on third parties with respect to its ability to implement its strategic plans. We cannot assure you that our security measures, change control procedures, and disaster recovery plans will be adequate to prevent disruptions or delays. Disruption in or changes to these systems could result in an interruption to our operations or loss of important data. Any of the foregoing could result in a material adverse effect on our business, reputation, results of operations and financial condition.

In order for our operations to work efficiently, our website and reservation system must be able to accommodate a high volume of traffic, maintain secure information and deliver flight information with a high degree of reliability. Substantially all of our tickets are issued to passengers as electronic tickets. We depend on our reservation system, which is hosted and maintained under a long-term contract by a third-party service provider, to be able to issue, track and accept these electronic

tickets. If our reservation system fails or experiences interruptions, and we are unable to book seats for any period of time, we could lose a significant amount of revenue as customers book seats on competing airlines. We have experienced short duration reservation system outages from time to time and may experience similar outages in the future. For example, in November 2010, we experienced a significant service outage with our third-party reservation service provider on the day before Thanksgiving, one of the industry’s busiest travel days and in August 2013, we experienced another 13 hour outage that affected our sales and customer service response times. We also rely on third-party service providers of our other automated systems for technical support, system maintenance and software upgrades. If our automated systems are not functioning or if the current providers were to fail to adequately provide technical support or timely software upgrades for any one of our key existing systems, we could experience service disruptions, which could harm our business and result in the loss of important data, increase our expenses and decrease our revenues. In the event that one or more of our primary technology or systems’ vendors goes into bankruptcy, ceases operations or fails to perform as promised, replacement services may not be readily available on a timely basis, at competitive rates or at all and any transition time to a new system may be significant.

In addition, our automated systems cannot be completely protected against events that are beyond our control, including natural disasters, cyber attacks or telecommunications failures. Substantial or sustained system failures could cause service delays or failures and result in our customers purchasing tickets from other airlines. We have implemented security measures and change control procedures and have disaster recovery plans; however, we cannot assure you that these measures are adequate to prevent disruptions. Disruption in, changes to or a breach of, these systems could result in a disruption to our business and the loss of important data. Moreover, in the event of system outages or interruptions, we may not be able to recover from our information technology and software providers all or any portion of the costs or business losses we may incur. Any of the foregoing could result in a material adverse effect on our business, results of operations and financial condition.

We are subject to cyber security risks and may incur increasing costs in an effort to minimize those risks.

Our business employs systems and websites that allow for the secure storage and transmission of proprietary or confidential information regarding our customers, employees, suppliers and others, including personal identification information, credit card data and other confidential information. Security breaches could expose us to a risk of loss or misuse of this information, litigation and potential liability. Although we take steps to secure our management information systems, and although multiple auditors review and approve the security configurations and management processes of these systems, including our computer systems, intranet and internet sites, email and other telecommunications and data networks, the security measures we have implemented may not be effective, and our systems may be vulnerable to theft, loss, damage and interruption from a number of potential sources and events, including unauthorized access or security breaches, natural or man-made disasters, cyber attacks, computer viruses, power loss, or other disruptive events. We may not have the resources or technical sophistication to anticipate or prevent rapidly evolving types of cyber attacks. Attacks may be targeted at us, our customers and suppliers, or others who have entrusted us with information. In addition, attacks not targeted at us, but targeted solely at suppliers, may cause disruption to our computer systems or a breach of the data that we maintain on customers, employees, suppliers and others.

Actual or anticipated attacks may cause us to incur increasing costs, including costs to deploy additional personnel and protection technologies, train employees and engage third-party experts and consultants, or costs incurred in connection with the notifications to employees, suppliers or the general public as part of our notification obligations to the various governments that govern our business. Advances in computer capabilities, new technological discoveries, or other developments may result in the breach or compromise of technology used by us to protect transaction or other data. In addition, data and security breaches can also occur as a result of non-technical issues, including breaches by us or by persons with whom we have commercial relationships that result in the unauthorized release of personal or confidential information. Our reputation, brand and financial condition could be adversely affected if, as a result of a significant cyber event or other security issues: our operations are disrupted or shut down; our confidential, proprietary information is stolen or disclosed; we incur costs or are required to pay fines in connection with stolen customer, employee or other confidential information; we must dedicate significant resources to system repairs or increase cyber security protection; or we otherwise incur significant litigation or other costs.

Our processing, storage, use and disclosure of personal data could give rise to liabilities as a result of governmental regulation.

In the processing of our customer transactions, we receive, process, transmit and store a large volume of identifiable personal data, including financial data such as credit card information. This data is increasingly subject to legislation and regulation, such as the Fair Accurate Credit Transparency Act and Payment Card Industry legislation, typically intended to protect the privacy of personal data that is collected, processed and transmitted. More generally, we rely on consumer confidence in the security of our system, including our website on which we sell the majority of our tickets. Our business, results of operations and financial condition could be adversely affected if we are unable to comply with existing privacy obligations or legislation or regulations are expanded to require changes in our business practices.

We may not be able to maintain or grow our non-ticket revenues.

Our business strategy includes expanding our portfolio of ancillary products and services. There can be no assurance that passengers will pay for additional ancillary products and services or that passengers will continue to choose to pay for the ancillary products and services we currently offer. Further, regulatory initiatives could adversely affect ancillary revenue opportunities. Failure to maintain our non-ticket revenues would have a material adverse effect on our results of operations and financial condition. Furthermore, if we are unable to maintain and grow our non-ticket revenues, we may not be able to execute our strategy to continue to lower base fares to address an underserved market. Please see “—Restrictions on or increased taxes applicable to charges for ancillary products and services paid by airline passengers and burdensome consumer protection regulations or laws could harm our business, results of operations and financial condition.”

Our inability to expand or operate reliably or efficiently out of our key airports where we maintain a large presence could have a material adverse effect on our business, results of operations and financial condition.

We are highly dependent on markets served from airports where we maintain a large presence. Our results of operations may be affected by actions taken by governmental or other agencies or authorities having jurisdiction over our operations at airports, including, but not limited to:


•	increases in airport rates and charges;


•	limitations on take-off and landing slots, airport gate capacity or other use of airport facilities;


•	termination of our airport use agreements, some of which can be terminated by airport authorities with little notice to us;


•	increases in airport capacity that could facilitate increased competition;


•	international travel regulations such as customs and immigration;


•	increases in taxes;


•	changes in the law that affect the services that can be offered by airlines in particular markets and at particular airports;


•	restrictions on competitive practices;


•	the adoption of statutes or regulations that impact customer service standards, including security standards; and


•	the adoption of more restrictive locally-imposed noise regulations or curfews.

In general, any changes in airport operations could have a material adverse effect on our business, results of operations and financial condition.

We rely on third-party service providers to perform functions integral to our operations.

We have entered into agreements with third-party service providers to furnish certain facilities and services required for our operations, including ground handling, catering, passenger handling, engineering, maintenance, refueling, reservations and airport facilities as well as administrative and support services. We are likely to enter into similar service agreements in new markets we decide to enter, and there can be no assurance that we will be able to obtain the necessary services at acceptable rates.

Although we seek to monitor the performance of third parties that provide us with our reservation system, ground handling, catering, passenger handling, engineering, maintenance services, refueling and airport facilities, the efficiency, timeliness and quality of contract performance by third-party service providers are often beyond our control, and any failure by our service providers to perform their contracts may have an adverse impact on our business and operations. For example, in 2008, our call center provider went bankrupt. Though we were able to quickly switch to an alternative vendor, we experienced a significant business disruption during the transition period and a similar disruption could occur in the future if we changed call center providers or if an existing provider ceased to be able to serve us. We expect to be dependent on such third-party arrangements for the foreseeable future.

We rely on third-party distribution channels to distribute a portion of our airline tickets.

We rely on third-party distribution channels, including those provided by or through global distribution systems, or GDSs, conventional travel agents and online travel agents, or OTAs, to distribute a portion of our airline tickets, and we expect in the future to rely on these channels to an increasing extent to collect ancillary revenues. These distribution channels are more expensive and at present have less functionality in respect of ancillary revenues than those we operate ourselves, such as our call centers and our website. Certain of these distribution channels also effectively restrict the manner in which we distribute our products generally. To remain competitive, we will need to successfully manage our distribution costs and rights, and improve the functionality of third-party distribution channels, while maintaining an industry-competitive cost structure. Negotiations with key GDSs and OTAs designed to manage our costs, increase our distribution flexibility, and improve functionality could be contentious, could result in diminished or less favorable distribution of our tickets, and may not provide the functionality we require to maximize ancillary revenues. Any inability to manage our third-party distribution costs, rights and functionality at a competitive level or any material diminishment in the distribution of our tickets could have a material adverse effect on our competitive position and our results of operations. Moreover, our ability to compete in the markets we serve may be threatened by changes in technology or other factors that may make our existing third-party sales channels impractical, uncompetitive, or obsolete.

We rely on a single service provider to manage our fuel supply.

As of December 31, 2015, we had a single fuel service contract with World Fuel Services Corporation to manage the sourcing and contracting of our fuel supply. A failure by this provider to fulfill its obligations could have a material adverse effect on our business, results of operations and financial condition.

Our reputation and business could be materially adversely affected in the event of an emergency, accident or similar incident involving our aircraft.

We are exposed to potential significant losses in the event that any of our aircraft is subject to an emergency, accident, terrorist incident or other similar incident, and significant costs related to passenger claims, repairs or replacement of a damaged aircraft and its temporary or permanent loss from service. There can be no assurance that we will not be affected by such events or that the amount of our insurance coverage will be adequate in the event such circumstances arise and any such event could cause a substantial increase in our insurance premiums. Please see “—Increases in insurance costs or significant reductions in coverage could have a material adverse effect on our business, financial condition and results of operations.” In addition, any future aircraft emergency, accident or similar incident, even if fully covered by insurance or even if it does not involve our airline, may create a public perception that our airline or the equipment we fly is less safe or reliable than other transportation alternatives, or could cause us to perform time consuming and costly inspections on our aircraft or engines which could have a material adverse effect on our business, results of operations and financial condition.

Negative publicity regarding our customer service or otherwise could have a material adverse effect on our business.

In the past, we have experienced a relatively high number of customer complaints related to, among other things, our customer service and reservations and ticketing systems. In particular, we generally experience a higher volume of complaints when we make changes to our unbundling policies, such as charging for baggage. In addition, in 2009, we entered into a consent order with the DOT for our procedures for bumping passengers from oversold flights and our handling of lost or damaged baggage. Under the consent order, we were assessed a civil penalty of $375,000, of which we were required to pay $215,000 based on an agreement with the DOT and our not having similar violations in the year after the date of the consent order. Further, media reports about incidents on our aircraft unrelated to customer complaints could negatively impact our reputation and our operations. If we do not meet our customers' expectations with respect to reliability and service, customers could decide not to fly with us, which would materially adversely affect our business and reputation.

We depend on a limited number of suppliers for our aircraft and engines.

One of the elements of our business strategy is to save costs by operating a single-family aircraft fleet - currently Airbus A320-family, single-aisle aircraft, powered by engines manufactured by IAE. If Airbus, IAE, or Pratt and Whitney become unable to perform its contractual obligations, or if we are unable to acquire or lease aircraft or engines from other owners, operators or lessors on acceptable terms, we would have to find other suppliers for a similar type of aircraft or engine. If we have to lease or purchase aircraft from another supplier, we would lose the significant benefits we derive from our current single fleet composition. We may also incur substantial transition costs, including costs associated with retraining our employees, replacing our manuals and adapting our facilities and maintenance programs. Our operations could also be harmed by the failure or inability of aircraft, engine and parts suppliers to provide sufficient spare parts or related support services on a timely basis. Our business would be significantly harmed if a design defect or mechanical problem with any of the types of aircraft or components that we operate were discovered that would ground any of our aircraft while the defect or problem was corrected, assuming it could be corrected at all. The use of our aircraft could be suspended or restricted by regulatory authorities in the event of any actual or perceived mechanical or design problems. Our business would also be significantly harmed if the public began to avoid flying with us due to an adverse perception of the types of aircraft that we operate stemming from safety concerns or other problems, whether real or perceived, or in the event of an accident involving those types of aircraft or components. Carriers that operate a more diversified fleet are better positioned than we are to manage such events.

Reduction in demand for air transportation, or governmental reduction or limitation of operating capacity, in the domestic U.S., Caribbean or Latin American markets could harm our business, results of operations and financial condition.

A significant portion of our operations are conducted to and from the domestic U.S., Caribbean or Latin American markets. Our business, results of operations and financial condition could be harmed if we lost our authority to fly to these markets, by any circumstances causing a reduction in demand for air transportation, or by governmental reduction or limitation of operating capacity, in these markets, such as adverse changes in local economic or political conditions, negative public perception of these destinations, unfavorable weather conditions, public health concerns or terrorist related activities. Furthermore, our business could be harmed if jurisdictions that currently limit competition allow additional airlines to compete on routes we serve. Many of the countries we serve are experiencing either economic slowdowns or recessions, which may translate into a weakening of demand and could harm our business, results of operations and financial condition.

Increases in insurance costs or significant reductions in coverage could have a material adverse effect on our business, financial condition and results of operations.

We carry insurance for third-party liability, passenger liability, property damage and all-risk coverage for damage to our aircraft. As a result of the September 11, 2001 terrorist attacks, aviation insurers significantly reduced the amount of insurance coverage available to commercial air carriers for liability to persons other than employees or passengers for claims resulting from acts of terrorism, war or similar events (war risk insurance). Accordingly, our insurance costs increased significantly and our ability to continue to obtain certain types of insurance remains uncertain. While the price of commercial insurance has declined since the period immediately after the terrorist attacks, in the event commercial insurance carriers further reduce the amount of insurance coverage available to us, or significantly increase its cost, we would be adversely affected. We currently maintain commercial airline insurance with several underwriters. However, there can be no assurance that the amount of such coverage will not be changed, or that we will not bear substantial losses from accidents. We could incur substantial claims resulting from an accident in excess of related insurance coverage that could have a material adverse effect on our results of operations and financial condition.

As of July 2014, we obtained war risk insurance from the commercial market which insures against some risks of terrorism. Previous to this date, we obtained this insurance through a special program administered by the FAA, which was discontinued late 2014. Renewing coverage from commercial underwriters may result in higher premiums and more restrictive terms. Our business, results of operations and financial condition could be materially adversely affected if we are unable to obtain adequate war risk insurance. Our current war risk hull and liability insurance policy is effective until July 2016.

Failure to comply with applicable environmental regulations could have a material adverse effect on our business, results of operations and financial condition.

We are subject to increasingly stringent federal, state, local and foreign laws, regulations and ordinances relating to the protection of the environment, including those relating to emissions to the air, discharges to surface and subsurface waters, safe drinking water and the management of hazardous substances, oils and waste materials. Compliance with all environmental laws and regulations can require significant expenditures and any future regulatory developments in the United States and abroad could adversely affect operations and increase operating costs in the airline industry. For example, climate change legislation was previously introduced in Congress and such legislation could be re-introduced in the future by Congress and state

legislatures, and could contain provisions affecting the aviation industry, compliance with which could result in the creation of substantial additional costs to us. Similarly, the Environmental Protection Agency issued a rule that regulates larger emitters of greenhouse gases. Future operations and financial results may vary as a result of such regulations. Compliance with these regulations and new or existing regulations that may be applicable to us in the future could increase our cost base and could have a material adverse effect on our business, results of operations and financial condition.

Governmental authorities in several U.S. and foreign cities are also considering or have already implemented aircraft noise reduction programs, including the imposition of nighttime curfews and limitations on daytime take-offs and landings. We have been able to accommodate local noise restrictions imposed to date, but our operations could be adversely affected if locally-imposed regulations become more restrictive or widespread.

If we are unable to attract and retain qualified personnel or fail to maintain our company culture, our business, results of operations and financial condition could be harmed.

Our business is labor intensive. We require large numbers of pilots, flight attendants, maintenance technicians and other personnel. The airline industry has from time to time experienced a shortage of qualified personnel, particularly with respect to pilots and maintenance technicians. In addition, as is common with most of our competitors, we have faced considerable turnover of our employees. We may be required to increase wages and/or benefits in order to attract and retain qualified personnel. If we are unable to hire, train and retain qualified employees, our business could be harmed and we may be unable to implement our growth plans.

In addition, as we hire more people and grow, we believe it may be increasingly challenging to continue to hire people who will maintain our company culture. Our company culture, which we believe is one of our competitive strengths, is important to providing high-quality customer service and having a productive, accountable workforce that helps keep our costs low. As we continue to grow, we may be unable to identify, hire or retain enough people who meet the above criteria, including those in management or other key positions. Our company culture could otherwise be adversely affected by our growing operations and geographic diversity. If we fail to maintain the strength of our company culture, our competitive ability and our business, results of operations and financial condition could be harmed.

Our business, results of operations and financial condition could be materially adversely affected if we lose the services of our key personnel.

Our success depends to a significant extent upon the efforts and abilities of our senior management team and key financial and operating personnel. In particular, we depend on the services of our senior management team. Competition for highly qualified personnel is intense, and the loss of any executive officer, senior manager, or other key employee without adequate replacement or the inability to attract new qualified personnel could have a material adverse effect on our business, results of operations and financial condition. We do not maintain key-man life insurance on our management team.

The requirements of being a public company may strain our resources, divert management’s attention and affect our ability to attract and retain qualified board members.

As a public company, we incur significant legal, accounting and other expenses, including costs associated with public company reporting requirements. We also have incurred and will continue to incur costs associated with the Sarbanes-Oxley Act of 2002, as amended, the Dodd-Frank Wall Street Reform and Consumer Protection Act and related rules implemented or to be implemented by the SEC and the NASDAQ Stock Market. The expenses incurred by public companies generally for reporting and corporate governance purposes have been increasing. We expect these rules and regulations to increase our legal and financial compliance costs and to make some activities more time-consuming and costly. These laws and regulations could also make it more difficult or costly for us to obtain certain types of insurance, including director and officer liability insurance, and we may be forced to accept reduced policy limits and coverage or incur substantially higher costs to obtain the same or similar coverage. These laws and regulations could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors, our board committees, or as our executive officers and may divert management’s attention. Furthermore, if we are unable to satisfy our obligations as a public company, we could be subject to delisting of our common stock, fines, sanctions and other regulatory action and potentially civil litigation.

We are required to assess our internal control over financial reporting on an annual basis, and any future adverse findings from such assessment could result in a loss of investor confidence in our financial reports, significant expenses to remediate any internal control deficiencies, and ultimately have an adverse effect on the market price of our common stock.

Pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, as amended, our management is required to report on, and our independent registered public accounting firm is required to attest to, the effectiveness of our internal control over financial

reporting. The rules governing the standards that must be met for management to assess our internal control over financial reporting are complex and require significant documentation, testing and possible remediation. Annually, we perform activities that include reviewing, documenting and testing our internal control over financial reporting. During the performance of these activities, we may encounter problems or delays in completing the implementation of any changes necessary to make a favorable assessment of our internal control over financial reporting. In connection with the attestation process by our independent registered public accounting firm, we may encounter problems or delays in completing the implementation of any requested improvements and receiving a favorable attestation. In addition, if we fail to maintain the adequacy of our internal control over financial reporting we will not be able to conclude on an ongoing basis that we have effective internal control over financial reporting in accordance with Section 404. If we fail to achieve and maintain an effective internal control environment, we could suffer material misstatements in our financial statements and fail to meet our reporting obligations, which would likely cause investors to lose confidence in our reported financial information. This could harm our operating results and lead to a decline in our stock price. Additionally, ineffective internal control over financial reporting could expose us to increased risk of fraud or misuse of corporate assets and subject us to potential delisting from the NASDAQ Global Select Market, regulatory investigations, civil or criminal sanctions and class action litigation.

The market price of our common stock may be volatile, which could cause the value of an investment in our stock to decline.

The market price of our common stock may fluctuate substantially due to a variety of factors, many of which are beyond our control, including:


•	announcements concerning our competitors, the airline industry or the economy in general;


•	strategic actions by us or our competitors, such as acquisitions or restructurings;


•	increased price competition;


•	media reports and publications about the safety of our aircraft or the aircraft type we operate;


•	new regulatory pronouncements and changes in regulatory guidelines;


•	changes in the price of aircraft fuel;


•	announcements concerning the availability of the type of aircraft we use;


•	general and industry-specific economic conditions;


•	changes in financial estimates or recommendations by securities analysts or failure to meet analysts’ performance expectations;


•	sales of our common stock or other actions by investors with significant shareholdings;


•	trading strategies related to changes in fuel or oil prices; and


•	general market, political and economic conditions.

The stock markets in general have experienced substantial volatility that has often been unrelated to the operating performance of particular companies. These types of broad market fluctuations may adversely affect the trading price of our common stock.

In the past, stockholders have sometimes instituted securities class action litigation against companies following periods of volatility in the market price of their securities. Any similar litigation against us could result in substantial costs, divert management’s attention and resources and harm our business or results of operations.

If securities or industry analysts do not publish research or reports about our business, or publish negative reports about our business, our stock price and trading volume could decline.

The trading market for our common stock depends in part on the research and reports that securities or industry analysts publish about us or our business. If one or more of the analysts who cover us downgrade our stock or publish inaccurate or unfavorable research about our business, our stock price would likely decline. If one or more of these analysts cease coverage of our company or fail to publish reports on us regularly, demand for our stock could decrease, which might cause our stock price and trading volume to decline.

Our anti-takeover provisions may delay or prevent a change of control, which could adversely affect the price of our common stock.

Our amended and restated certificate of incorporation and amended and restated bylaws contain provisions that may make it difficult to remove our board of directors and management and may discourage or delay “change of control” transactions, which could adversely affect the price of our common stock. These provisions include, among others:


•	our board of directors is divided into three classes, with each class serving for a staggered three-year term, which prevents stockholders from electing an entirely new board of directors at an annual meeting;


•	actions to be taken by our stockholders may only be effected at an annual or special meeting of our stockholders and not by written consent;


•	special meetings of our stockholders can be called only by the Chairman of the Board or by our corporate secretary at the direction of our board of directors;


•	advance notice procedures that stockholders must comply with in order to nominate candidates to our board of directors and propose matters to be brought before an annual meeting of our stockholders may discourage or deter a potential acquirer from conducting a solicitation of proxies to elect the acquirer’s own slate of directors or otherwise attempting to obtain control of our company; and


•	our board of directors may, without stockholder approval, issue series of preferred stock, or rights to acquire preferred stock, that could dilute the interest of, or impair the voting power of, holders of our common stock or could also be used as a method of discouraging, delaying or preventing a change of control.

Our corporate charter and bylaws include provisions limiting voting by non-U.S. citizens and specifying an exclusive forum for stockholder disputes.

To comply with restrictions imposed by federal law on foreign ownership of U.S. airlines, our amended and restated certificate of incorporation and amended and restated bylaws restrict voting of shares of our common stock by non-U.S. citizens. The restrictions imposed by federal law currently require that no more than 25% of our stock be voted, directly or indirectly, by persons who are not U.S. citizens, and that our president and at least two-thirds of the members of our board of directors and senior management be U.S. citizens. Our amended and restated bylaws provide that the failure of non-U.S. citizens to register their shares on a separate stock record, which we refer to as the “foreign stock record,” would result in a suspension of their voting rights in the event that the aggregate foreign ownership of the outstanding common stock exceeds the foreign ownership restrictions imposed by federal law.

Our amended and restated bylaws further provide that no shares of our common stock will be registered on the foreign stock record if the amount so registered would exceed the foreign ownership restrictions imposed by federal law. If it is determined that the amount registered in the foreign stock record exceeds the foreign ownership restrictions imposed by federal law, shares will be removed from the foreign stock record in reverse chronological order based on the date of registration therein, until the number of shares registered therein does not exceed the foreign ownership restrictions imposed by federal law. As of December 31, 2015, we believe we were in compliance with the foreign ownership rules.

As of December 31, 2015, there are no shares of non-voting common stock outstanding. When shares of non-voting common stock are outstanding, the holders of such stock may convert such shares, on a share-for-share basis, in the order reflected on our foreign stock record as shares of common stock are sold or otherwise transferred by non-U.S. citizens to U.S. citizens.

Our amended and restated certificate of incorporation also specifies that the Court of Chancery of the State of Delaware shall be the exclusive forum for substantially all disputes between us and our stockholders.

We do not intend to pay cash dividends for the foreseeable future.

We have never declared or paid cash dividends on our common stock. We currently intend to retain our future earnings, if any, to finance the further development and expansion of our business and do not intend to pay cash dividends in the foreseeable future. Any future determination to pay dividends will be at the discretion of our board of directors and will depend on our financial condition, results of operations, capital requirements, restrictions contained in current or future financing instruments, business prospects and such other factors as our board of directors deems relevant.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

ITEM 2. PROPERTIES

Aircraft

As of December 31, 2015, we operated a fleet of 79 aircraft as detailed in the following table:



Aircraft Type	Seats	Average Age (years)	Number of Aircraft	Number Owned	Number Leased
A319	145	9.6	29	—	29
A320	178	2.6	42	12	30
A321	218 - 228	2.8	8	6	2
		5.2	79	18	61

As of December 31, 2015, our firm aircraft orders, consisted of 87 A320 family aircraft with Airbus (13 A320ceos, 40 A320neos, 24 A321ceos and 10 A321neos) and an additional 5 direct operating leases for A320neos with a third-party lessor. As of December 31, 2015, our future fleet plan, net of contractual lease returns, is illustrated in the table below.



Aircraft Type	2016	2017	2018	2019	2020	2021
A319	26	22	17	16	9	5
A320	45	53	55	55	55	55
A320neo	5	5	11	14	27	45
A321	17	25	30	30	30	30
A321neo	—	—	—	10	10	10
Total Aircraft	93	105	113	125	131	145

Note 1: Actual fleet count may differ depending on future fleet decisions, including actual lease retirements.

Note 2: We have been notified by our third-party lessor that the delivery of one or more of the A320neos scheduled for 2016 may be delayed until 2017. We do not believe this delay in delivery date to be significant.

We also have four spare engine orders for V2500 SelectOne engines with IAE and nine spare engine orders for PurePower PW 1100G-JM engines with Pratt & Whitney. Spare engines are scheduled for delivery from 2017 through 2023.

Ground Facilities

We lease all of our facilities at each of the airports we serve. Our leases for terminal passenger service facilities, which include ticket counter and gate space, operations support areas and baggage service offices, generally have a term ranging from month-to-month to 16 years, and contain provisions for periodic adjustments of lease rates. We also are responsible for maintenance, insurance and other facility-related expenses and services. We also have entered into use agreements at the airports we serve that provide for the non-exclusive use of runways, taxiways and other airfield facilities. Landing fees paid under these agreements are based on the number of landings and weight of the aircraft.

As of December 31, 2015, Ft. Lauderdale/Hollywood International Airport (FLL) remained our single largest airport served, with approximately 13% of our capacity operating from FLL during 2015. We operate primarily out of Terminal 4 at FLL, the international terminal. We currently use up to ten gates simultaneously at Terminal 4. We have preferential access to seven of the Terminal 4 gates, common use access to the remaining three Terminal 4 gates, and access to other Terminal 3 gates. FLL is in the middle of a concourse replacement and expansion project, which will expand the number of gates at Terminal 4 from 10 to 14. Other airports through which we conduct significant operations include Chicago O'Hare International Airport (ORD), McCarran International Airport (LAS) serving Las Vegas, Dallas-Fort Worth International Airport (DFW), Detroit Metropolitan Wayne County Airport (DTW) and George Bush Intercontinental Airport (IAH).

Our largest maintenance facility is currently located in a leased facility at FLL under a lease that expires in January 2022. We also conduct additional maintenance operations in leased facilities in Detroit, Michigan; Chicago, Illinois; Atlantic City, New Jersey; Dallas, Texas; Houston, Texas; and Las Vegas, Nevada.

In September 2015, we executed a lease agreement with Wayne County Airport Authority (the Authority), which owns and operates Detroit Metropolitan Wayne County Airport (DTW). Under the lease agreement, we lease a 10-acre site, adjacent to the airfield at DTW, in order to construct, operate and maintain an approximately 126,000 square foot hangar facility (the project). The project allows for the development of a maintenance hangar in order to fulfill the requirements of our growing fleet and will reduce dependence on third-party facilities and contract line maintenance. The lease agreement has a 30-year term with two 10-year extension options. Upon termination of the lease, title of the project, which will be fully depreciated, will automatically pass to the Authority. We estimate to complete the project during the third quarter of 2016.

Our principal executive offices and headquarters are located in a leased facility at 2800 Executive Way, Miramar, Florida 33025, consisting of approximately 56,000 square feet. The lease for this facility expires in January 2025. In January 2014, we expanded our principal executive offices and headquarters by leasing an additional facility located at 2844 Corporate Way, Miramar, Florida 33025, consisting of approximately 15,000 square feet. The lease for this facility expires in January 2025. We also have a training center located in a leased facility at 1050 Lee Wagener Boulevard, Fort Lauderdale, Florida 33315, consisting of approximately 12,000 square feet, under a lease that expires in January 2020.

ITEM 3. LEGAL PROCEEDINGS

We are subject to commercial litigation claims and to administrative and regulatory proceedings and reviews that may be asserted or maintained from time to time. We believe the ultimate outcome of pending lawsuits, proceedings and reviews will not, individually or in the aggregate, have a material adverse effect on our financial position, liquidity, or results of operations.

ITEM 4. MINE SAFETY DISCLOSURES

Not applicable.

PART II

ITEM 5. MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

Market Price of our common stock

Our common stock is listed and traded on the NASDAQ Global Select Market under the symbol "SAVE." The following table shows, for the periods indicated, the high and low per share sales prices for our common stock on the NASDAQ Global Select Market.



	High		Low
Fiscal year ended December 31, 2014
First Quarter	$	63.05	$	44.76
Second Quarter	63.80		54.22
Third Quarter	73.31		62.41
Fourth Quarter	84.47		53.31
Fiscal year ended December 31, 2015
First Quarter	$	82.03	$	69.64
Second Quarter	77.88		59.98
Third Quarter	63.54		46.95
Fourth Quarter	50.80		33.57

As of February 10, 2016, there were approximately 52 holders of record of our common stock. Because many of our shares are held by brokers and other institutions on behalf of stockholders, we are unable to estimate the total number of stockholders represented by the holders.

The information under the caption “Equity Compensation Plan Information” in our 2016 Proxy Statement is incorporated herein by reference.

Dividend Policy

We have never declared or paid, and do not anticipate declaring or paying, any cash dividends on our common stock. Any future determination as to the declaration and payment of dividends, if any, will be at the discretion of our board of directors and will depend on then existing conditions, including our financial condition, operating results, contractual restrictions, capital requirements, business prospects and other factors our board of directors may deem relevant.

Our Repurchases of Equity Securities

The following table reflects our repurchases of our common stock during the fourth quarter of 2015. All stock repurchases during this period were made from employees who received restricted stock grants. All employee stock repurchases were made at the election of each employee pursuant to an offer to repurchase by us. In each case, the shares repurchased constituted the portion of vested shares necessary to satisfy minimum withholding tax requirements.



ISSUER PURCHASES OF EQUITY SECURITIES

Period	Total Number of Shares Purchased	Average Price Paid per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs	Approximate Dollar Value of Shares that May Yet be Purchased Under Plans or Programs
October 1-31, 2015	1,335	$	44.52	—	$	100,581,852
November 1-30, 2015	1,147	$	34.00	—	$	100,581,852
December 1-31, 2015	—	N/A		—	$	100,000,000
Total	2,482	$	40.87	—

During the first three quarters of 2015, we repurchased and retired 1.7 million shares for a total of $102.1 million. Repurchases of equity securities during this period include repurchases made from employees who received restricted stock or performance share awards as well as open market repurchases made under our stock repurchase authorization that became effective in December 2014, which authorized the repurchase of up to $100 million of our common stock. This authorization expired on December 31, 2015. Shares repurchased from employees constituted the portion of vested shares necessary to satisfy withholding tax requirements.

On October 26, 2015, our Board of Directors authorized a new repurchase program of up to $100 million in aggregate value of shares of our Common Stock, par value $0.0001 per share. These repurchases can be made from time to time in open market or privately negotiated transactions. This authorization will expire on October 26, 2016. The timing and amount of any stock repurchase is subject to prevailing market conditions and other considerations, and may be discontinued at any time. As of December 31, 2015, no repurchases have been made under this new repurchase plan.

Stock Performance Graph

The following graph compares the cumulative total stockholder return on our common stock with the cumulative total return on the NASDAQ Composite Index and the NYSE ARCA Airline Index for the period beginning on May 26, 2011 (the date our common stock was first traded) and ending on December 31, 2015. The graph assumes an investment of $100 in our stock and the two indices, respectively, on May 26, 2011, and further assumes the reinvestment of all dividends. The May 26, 2011 stock price used for our stock is the initial public offering price. Stock price performance, presented for the period from May 26, 2011 to December 31, 2015, is not necessarily indicative of future results.



	5/26/2011		12/31/2011		12/31/2012		12/31/2013		12/31/2014		12/31/2015
Spirit	$	100.00	$	130.00	$	147.75	$	378.42	$	629.83	$	332.08
NYSE ARCA Airline Index	$	100.00	$	75.49	$	104.07	$	164.74	$	247.45	$	209.67
NASDAQ Composite Index	$	100.00	$	94.23	$	110.94	$	155.50	$	178.56	$	191.25

ITEM 6. SELECTED FINANCIAL DATA

You should read the following selected historical financial and operating data below in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the financial statements, related notes and other financial information included in this annual report. The selected financial data in this section are not intended to replace the financial statements and are qualified in their entirety by the financial statements and related notes included in this annual report.

We derived the selected statements of operations data for the years ended December 31, 2015, 2014 and 2013 and the balance sheet data as of December 31, 2015 and 2014 from our audited financial statements included in this annual report. We derived the selected statements of operations data for the years ended December 31, 2012 and 2011 and the balance sheet data as of December 31, 2013, 2012 and 2011 from our audited financial statements not included in this annual report. Our historical results are not necessarily indicative of the results to be expected in the future.



	Year Ended December 31,
	2015			2014			2013			2012			2011
	(in thousands, except share and per share data)
Operating revenues:
Passenger	$	1,169,338		$	1,144,972		$	986,018		$	782,792		$	689,650
Non-ticket	972,125			786,608			668,367			535,596			381,536
Total operating revenue	2,141,463			1,931,580			1,654,385			1,318,388			1,071,186
Operating expenses:
Aircraft fuel (1)	461,447			612,909			551,746			471,763			388,046
Salaries, wages and benefits	378,210			313,988			262,150			218,919			181,742
Aircraft rent	211,531			195,827			169,737			143,572			116,485
Landing fees and other rents	131,077			105,115			83,604			68,368			52,794
Distribution	86,576			74,823			67,481			56,668			51,349
Maintenance, materials and repairs	80,448			73,956			60,143			49,460			34,017
Depreciation and amortization	73,908			46,971			31,947			15,256			7,760
Other operating	206,867			149,675			144,586			127,886			91,172
Loss on disposal of assets	1,604			3,008			525			956			255
Special charges (credits) (2)	673			45			174			(8,450		)	3,184
Total operating expenses	1,632,341			1,576,317			1,372,093			1,144,398			926,804
Operating income	509,122			355,263			282,292			173,990			144,382
Other expense (income):
Interest expense (3)	20,382			2,747			214			1,350			24,781
Capitalized interest (4)	(11,553		)	(2,747		)	(214		)	(1,350		)	(2,890		)
Interest income	(2,125		)	(336		)	(401		)	(925		)	(575		)
Other expense	15			2,605			283			331			235
Total other expense (income)	6,719			2,269			(118		)	(594		)	21,551
Income before income taxes	502,403			352,994			282,410			174,584			122,831
Provision for income taxes	185,183			127,530			105,492			66,124			46,383
Net income	$	317,220		$	225,464		$	176,918		$	108,460		$	76,448
Earnings Per Share:
Basic	$	4.39		$	3.10		$	2.44		$	1.50		$	1.44
Diluted	$	4.38		$	3.08		$	2.42		$	1.49		$	1.43
Weighted average shares outstanding:
Basic	72,207,725			72,738,961			72,592,765			72,385,574			53,240,898
Diluted	72,426,060			73,293,869			72,999,221			72,590,574			53,515,348


(1)	Aircraft fuel expense is the sum of (i) “into-plane fuel cost,” which includes the cost of jet fuel and certain other charges such as fuel taxes and oil, (ii) realized gains and losses related to fuel derivative contracts and (iii) unrealized gains and losses related to fuel derivative contracts. The following table summarizes the components of aircraft fuel expense for the periods presented:



	Year Ended December 31,
	2015			2014		2013		2012		2011
	(in thousands)
Into-plane fuel cost	$	454,747		$	608,033	$	542,523	$	471,542	$	392,278
Realized losses (gains) related to fuel derivatives contracts, net	10,580			995		8,958		175		(7,436		)
Unrealized losses (gains) related to fuel derivative contracts, net	(3,880		)	3,881		265		46		3,204
Aircraft fuel expense	$	461,447		$	612,909	$	551,746	$	471,763	$	388,046

(2)

Special charges (credits) include: (i) for 2011 amounts relating to exit facility costs associated with moving our Detroit, Michigan maintenance operations to Fort Lauderdale, Florida; (ii) termination costs in connection with the IPO during the three months ended June 30, 2011 comprised of amounts paid to Indigo Partners, LLC to terminate its professional services agreement with us and fees paid to three individual, unaffiliated holders of our subordinated notes; (iii) for 2011 and 2012, a $9.1 million gain related to the sale of four permanent air carrier slots at Ronald Reagan National Airport (DCA) offset by costs connected with the 2012 secondary offerings; and for 2013, costs related to the 2013 secondary offering; (iv) for 2013 and 2014, $0.1 million in costs related to the DCA exit; (v) for 2015, amounts related to restructuring charges for outsourcing of ramps and passenger services.

(3)

Substantially all of the interest expense recorded in 2011 relates to notes and preferred stock held by our principal stockholders that were repaid or redeemed, or exchanged for shares of common stock, in connection with the Recapitalization in 2011 that was effected in connection with the IPO. Interest expense in 2012 and 2013 primarily relates to interest related to the TRA. Interest expense in 2014 primarily relates to interest related to the long-term debt, commitment fees and underpayment of Federal Excise Tax for fuel purchases during the period between July 1, 2009 and August 31, 2014. Interest expense in 2015 primarily relates to interest related to financing of purchasing aircraft.


(4)	Interest attributable to funds used to finance the acquisition of new aircraft, including PDPs is capitalized as an additional cost of the related asset. In 2015 capitalized interest primarily represents interest related to the financing of purchased aircraft.

The following table presents balance sheet data for the periods presented:



	As of December 31,
	2015		2014		2013		2012		2011
Balance Sheet Data:	(in thousands)
Cash and cash equivalents	$	803,632	$	632,784	$	530,631	$	416,816	$	343,328
Total assets (5)	2,530,545		1,592,753		1,164,522		907,293		733,705
Long-term debt, including current portion	646,330		145,663		—		—		—
Stockholders' equity	1,225,310		1,003,075		769,117		582,535		466,706


(5)	Prior period amounts have been reclassified to conform to ASU No. 2015-17 (ASU 2015-17), "Income Taxes" issued in November 2015. For additional information, please see "Notes to Financial Statements—2. Recent Accounting Developments."

OPERATING STATISTICS



	Year Ended December 31,
	2015	2014	2013	2012	2011
Operating Statistics (unaudited) (A)
Average aircraft	72.7	57.7	49.9	41.2	34.8
Aircraft at end of period	79	65	54	45	37
Airports served in the period (B)	57	56	56	55	50
Average daily Aircraft utilization (hours)	12.7	12.7	12.7	12.8	12.7
Average stage length (miles)	987	980	958	909	921
Block hours	337,956	267,305	231,148	192,403	161,898
Departures	128,902	102,594	90,284	78,582	65,565
Passenger flight segments (thousands)	17,921	14,294	12,414	10,423	8,518
Revenue passenger miles (RPMs) (thousands)	17,995,311	14,159,860	12,001,088	9,663,721	8,006,748
Available seat miles (ASMs) (thousands)	21,246,156	16,340,142	13,861,393	11,344,731	9,352,553
Load factor (%)	84.7	86.7	86.6	85.2	85.6
Average ticket revenue per passenger flight segment ($)	65.25	80.11	79.43	75.11	80.97
Average non-ticket revenue per passenger flight segment ($)	54.24	55.03	53.84	51.39	44.79
Total revenue per passenger segment ($)	119.49	135.14	133.27	126.50	125.76
Average yield (cents)	11.90	13.64	13.79	13.64	13.38
Total operating revenue per ASM (TRASM) (cents)	10.08	11.82	11.94	11.62	11.45
CASM (cents)	7.68	9.65	9.90	10.09	9.91
Adjusted CASM (cents) (C)	7.69	9.55	9.89	10.15	9.84
Adjusted CASM ex fuel (cents) (D)	5.50	5.88	5.91	6.00	5.72
Fuel gallons consumed (thousands)	255,008	200,498	171,931	142,991	121,030
Average economic fuel cost per gallon ($)	1.82	2.99	3.21	3.30	3.18


(A)	See “Glossary of Airline Terms” elsewhere in this annual report for definitions of terms used in this table.


(B)	Includes seasonal airports not served at the end of the period. Prior to 2013, we reported only airports served during the period with continuing operations.


(C)	Reconciliation of CASM to Adjusted CASM:



	Year Ended December 31,
	2015					2014			2013			2012					2011
	(in millions)			Per ASM		(in millions)		Per ASM	(in millions)		Per ASM	(in millions)			Per ASM		(in millions)		Per ASM
CASM (cents)				7.68				9.65			9.90				10.09				9.91
Unrealized losses (gains) related to fuel derivative contracts	$	(3.9	)	(0.02	)	$	3.9	0.02	$	0.3	—	$	—		—		$	3.2	0.03
Loss on disposal of assets	1.6			0.01		3.0		0.02	0.5		—	1.0			0.01		0.3
Special charges (credits)	0.7			—		—		—	0.2		—	(8.5		)	(0.07	)	3.2		0.03
Out of period fuel excise tax	—			—		9.3		0.06	—		—	—			—		—
Adjusted CASM (cents)				7.69				9.55			9.89				10.15				9.84


(D)	Excludes aircraft fuel expense, loss on disposal of assets, and special charges.

ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion of our financial condition and results of operations in conjunction with the financial statements and the notes thereto included elsewhere in this annual report.

2015 Year in Review

The year 2015 marks our ninth consecutive year of profitability. In 2015, we increased our capacity by 30.0%, as we grew our fleet of Airbus single-aisle aircraft from 65 to 79 aircraft, launched service to 40 new markets and added 1 new destination: Cleveland, Ohio.

During 2015, we earned net income of $317.2 million ($4.38 per share, diluted), compared to net income of $225.5 million ($3.08 per share, diluted) in 2014. The increase in earnings was a result of our increased capacity as well as lower fuel and non-fuel unit costs, which allowed us to continue generating high profit margins.

For the year ended December 31, 2015, we achieved an operating profit margin of 23.8%, the highest in our history, on $2,141.5 million in operating revenues. Our traffic grew by 27.1% as we continued to address an underserved market with ultra-low fares. Increased competitive pressures from major domestic network carriers aggressively discounting fares led to a 12.8% decrease in passenger yields year over year. As a result of this pricing environment, TRASM in 2015 was 10.08 cents, a decrease of 14.7% compared to the prior year period. Total revenue per passenger flight segment decreased 11.6%, year over year, from $135.14 to $119.49 driven by a decrease of 18.5% in ticket revenue per passenger flight segment.

Our total non-ticket revenue increased by 23.6%, or $185.5 million, to $972.1 million in 2015. Despite the increased competitive pressures during 2015, our average non-ticket revenue per passenger flight segment remained relatively stable with a decline of only 1.4%, to $54.24. Our unbundling model provides a more stable revenue stream as demonstrated during periods of lower passenger ticket yields.

Our operating cost structure is a primary area of focus and is at the core of our ULCC business model in which we compete solely on the basis of price. Our unit operating costs continue to be among the lowest of any airline in the United States. During 2015, our adjusted CASM ex-fuel decreased by 6.5% to 5.50 cents. The decrease on a per unit basis was primarily due to a decrease in aircraft rent and in salaries, wages and benefits. The decrease in aircraft rent per ASM was driven by a change in the mix of leased and purchased aircraft. Labor expense per ASM in 2015 was lower, as compared to prior year, due to scale benefits from overall growth and the introduction of larger gauge aircraft. These decreases were partially offset by higher depreciation and amortization expense related to the depreciation of purchased aircraft.

During 2015, we took delivery of 14 new aircraft, of which 11 are financed through senior and junior long-term debt and 3 are financed through an EETC. This EETC was our first aircraft-backed bond publicly offered by the Company. As of December 31, 2015, our 79 Airbus A320-family aircraft fleet was comprised of 29 A319s, 42 A320s and 8 A321s, of which 18 are owned and 61 are financed under operating leases. As of December 31, 2015, our aircraft orders consisted of 87 A320 family aircraft with Airbus and an additional 5 direct operating leases for A320neos with a third party, scheduled for delivery from 2016 through 2021.

Operating Revenues

Our operating revenues are comprised of passenger revenues and non-ticket revenues.

Passenger Revenues. Passenger revenues consist of the base fares that customers pay for air travel.

Non-ticket Revenues. Non-ticket revenues are generated from air travel-related charges for baggage, passenger usage fee (PUF) for bookings through certain of our distribution channels, advance seat selection, itinerary changes, hotel and rental car travel packages and loyalty programs such as our FREE SPIRIT affinity credit card program and $9 Fare Club. Non-ticket revenues also include revenues derived from the sale of advertising to third parties on our website and on board our aircraft.

Substantially all of our revenues are denominated in U.S. dollars. Passenger revenues, as well as most non-ticket revenues, are recognized once the related flight departs. Accordingly, the value of tickets and portions of non-ticket revenues sold in advance of travel is included under our current liabilities as “air traffic liability,” or ATL, until the related air travel is provided. Some of our non-ticket revenues are recognized at the time the ancillary products are purchased or ancillary services are provided, such as revenues from our subscription-based $9 Fare Club, which we recognize on a straight-line basis over 12

months. Revenue generated from the FREE SPIRIT credit card affinity program are recognized in accordance with the criteria as set forth in Accounting Standards Update ASU No. 2009-13. Please see “—Critical Accounting Policies and Estimates—Frequent Flier Program.”

We recognize revenues net of certain taxes and airport passenger fees, which are collected by us on behalf of airports and governmental agencies and remitted to the applicable governmental entity or airport on a periodic basis. These taxes and fees include U.S. federal transportation taxes, federal security charges, airport passenger facility charges and foreign arrival and departure taxes. These items are collected from customers at the time they purchase their tickets, but are not included in our revenues. We record a liability upon collection from the customer and relieve the liability when payments are remitted to the applicable governmental agency or airport.

Operating Expenses

Our operating expenses consist of the following line items.

Aircraft Fuel. Aircraft fuel expense is our single largest operating expense. It includes the cost of jet fuel, related federal taxes, fueling into-plane fees and transportation fees. It also includes realized and unrealized gains and losses arising from any activity on our fuel derivatives. Our fuel derivatives generally consist of United States Gulf Coast jet fuel swaps (jet fuel swaps) and United States Gulf Coast jet fuel options (jet fuel options).

Salaries, Wages and Benefits. Salaries, wages and benefits expense includes the salaries, hourly wages, bonuses and equity compensation paid to employees for their services, as well as the related expenses associated with employee benefit plans and employer payroll taxes.

Aircraft Rent. Aircraft rent expense consists of monthly lease rents for aircraft and spare engines under the terms of the related operating leases and is recognized on a straight-line basis. Aircraft rent expense also includes supplemental rent. Supplemental rent is made up of maintenance reserves paid or expected to be paid to aircraft lessors in advance of the performance of major maintenance activities that are not probable of being reimbursed and lease return condition obligations which we begin to accrue when they are probable. Aircraft rent expense is net of the amortization of gains and losses on sale and leaseback transactions on our flight equipment. As of December 31, 2015, 61 of our 79 aircraft and all of our 11 spare engines are financed under operating leases.

Landing Fees and Other Rents. Landing fees and other rents include both fixed and variable facilities expenses, such as the fees charged by airports for the use or lease of airport facilities, overfly fees paid to other countries and the monthly rent paid for our headquarters facility.

Distribution. Distribution expense includes all of our direct costs including the cost of web support, our third-party call center, travel agent commissions and related GDS fees and credit card transaction fees, associated with the sale of our tickets and other products and services.

Maintenance, Materials and Repairs. Maintenance, materials and repairs expense includes parts, materials, repairs and fees for repairs performed by third-party vendors directly required to maintain our fleet. It excludes direct labor cost related to our own mechanics, which is included under salaries, wages and benefits. It also excludes the amortization of heavy maintenance expenses, which we defer under the deferral method of accounting and amortize as a component of depreciation and amortization expense.

Depreciation and Amortization. Depreciation and amortization expense includes the depreciation of fixed assets we own and leasehold improvements. It also includes the amortization of heavy maintenance expenses we defer under the deferral method of accounting for heavy maintenance events and recognize into expense on a straight-line or usage basis until the earlier of the next estimated heavy maintenance event or the remaining lease term.

Loss on Disposal of Assets. Loss on disposal of assets includes the net losses on the disposal of our fixed assets.

Other Operating Expenses. Other operating expenses include airport operations expense and fees charged by third-party vendors for ground handling services and food and liquor supply service expenses, passenger re-accommodation expense, the cost of passenger liability and aircraft hull insurance, all other insurance policies except for employee related insurance, travel and training expenses for crews and ground personnel, professional fees, personal property taxes and all other administrative and operational overhead expenses. No individual item included in this category represented more than 5% of our total operating expenses.

Special Charges. Special charges include termination costs and secondary offering costs.

Other Expense (Income)

Interest Expense. Interest expense in 2015 was primarily related to the financing of purchased aircraft. For 2014, interest expense primarily represented interest related to the financing of purchased aircraft, interest related to the underpayment of prior year jet fuel FET and interest charged under the Tax Receivable Agreement (TRA). Interest expense in 2013 primarily related to interest on the TRA. For a detailed discussion of the TRA, see “Notes to the Financial Statements—17. Tax Receivable Agreement.”

Capitalized Interest. Capitalized interest represents interest cost incurred during the acquisition period of an aircraft which theoretically could have been avoided had we not made PDPs for that aircraft. The percent of interest expense capitalized is equal to the amount of interest which could have been avoided. As such, if the amount of PDPs on deposit is less than the amount of related debt on which interest is incurred, then only a percent of total incurred interest expense qualifies for capitalization. These amounts are capitalized as part of the cost of the aircraft upon delivery. Capitalization of interest ceases when the asset is ready for service. Capitalized interest for 2015 primarily related to the interest incurred on long-term debt. For 2014, capitalized interest related to interest incurred on long-term debt, underpayment of prior year jet fuel FET and interest charged under the TRA. For 2013, capitalized interest related to interest incurred in connection with payments owed under the TRA.

Interest Income. For 2015, interest income was related to interest earned on funds required to be held in escrow in accordance with the terms of our EETC. For a detailed discussion of the EETC, see “Notes to the Financial Statements—9. Debt and Other Obligations.”

Other Expense. For 2014, other expense included $1.4 million related to the tax receivable settlement amount in excess of the amount previously accrued for. In addition, for 2014, other expense included a charitable contribution of $1.0 million that is specifically creditable against current income tax in the State of Florida, as allowed under state law.

Income Taxes

We account for income taxes using the liability method. We record a valuation allowance to reduce the deferred tax assets reported if, based on the weight of the evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Deferred taxes are recorded based on differences between the financial statement basis and tax basis of assets and liabilities and available tax loss and credit carryforwards. In assessing the realizability of the deferred tax assets, we consider whether it is more likely than not that some or all of the deferred tax assets will be realized. In evaluating the ability to utilize our deferred tax assets, we consider all available evidence, both positive and negative, in determining future taxable income on a jurisdiction by jurisdiction basis.

In connection with our IPO in 2011, we entered into the TRA and thereby distributed immediately prior to the completion of the IPO to the holders of common stock as of such time, or the Pre-IPO Stockholders, the right to receive an amount equal to 90% of the cash savings in federal income tax realized by it by virtue of the use of the federal net operating loss, deferred interest deductions and alternative minimum tax credits held by us as of March 31, 2011, which was defined as the Pre-IPO NOL. Cash tax savings were generally computed by comparing actual federal income tax liability to the amount of such taxes that we would have been required to pay had such Pre-IPO NOLs (as defined in the TRA) not been available. Upon consummation of the IPO and execution of the TRA, we recorded a liability with an offsetting reduction to additional paid in capital. The amount and timing of payments under the TRA depended upon a number of factors, including, but not limited to, the amount and timing of taxable income generated in future periods and any limitations that may have been imposed on our ability to use the Pre-IPO NOLs. The term of the TRA was to continue until the first to occur (a) the full payment of all amounts required under the agreement with respect to utilization or expiration of all of the Pre-IPO NOLs, (b) the end of the taxable year including the tenth anniversary of the IPO or (c) a change in control of the Company.

In accordance with the TRA, we were required to submit a Tax Benefit Schedule showing the proposed TRA payout amount to the Stockholder Representatives within 45 calendar days of filing our tax return. Stockholder Representatives were defined as Indigo Pacific Partners, LLC and OCM FIE, LLC, representing the two largest ownership interest of pre-IPO shares. The Tax Benefit Schedule was to become final and binding on all parties unless a Stockholder Representative, within 45 calendar days after receiving such schedule, provided us with notice of a material objection to such schedule. If the parties, for any reason, were unable to successfully resolve the issues raised in any notice within 30 calendar days of receipt of such notice, we and the Stockholder Representatives had the right to employ the reconciliation procedures as set forth in the TRA. If the Tax Benefit Schedule was accepted, we then had five days after acceptance to make payments to the Pre-IPO stockholders. Pursuant to the TRA's reconciliation procedures, any disputes that could not be settled amicably, were to be settled by arbitration conducted by a single arbitrator jointly selected by both parties.

During the second quarter of 2012, we paid $27.2 million, or 90% of the 2011 tax savings realized from the utilization of NOLs, including $0.3 million of applicable interest, to the Pre-IPO Stockholders.

During 2013, we filed an amended 2009 income tax return which resulted in a reduction to the estimated TRA liability from $8.0 million to $5.6 million. On September 13, 2013, we filed our 2012 federal income tax return, and on October 14, 2013, we submitted a Tax Benefit Schedule to the Stockholder Representatives. On November 27, 2013, pursuant to the TRA, we received an objection notice to the Tax Benefit Schedule from the Stockholder Representatives. On April 7, 2014, we received a demand for arbitration from the Stockholder Representatives. Prior to commencing arbitration proceedings, on June 17, 2014, we and Stockholder Representatives agreed on a settlement amount of $7.0 million in addition to interest of $0.3 million. The agreed upon settlement was in excess of the outstanding liability of $5.6 million at the time of settlement. The excess payment of $1.4 million was recorded within other expense in the statement of operations and recorded as cash from operations in the statement of cash flows. We have made all payments in accordance with the agreed upon settlement terms and have no outstanding obligations related to the TRA.

Trends and Uncertainties Affecting Our Business

We believe our operating and business performance is driven by various factors affecting airlines and their markets, trends affecting the broader travel industry and trends affecting the specific markets and customer base that we target. The following key factors may affect our future performance.

Competition. The airline industry is highly competitive. The principal competitive factors in the airline industry are fare pricing, total price, flight schedules, aircraft type, passenger amenities, number of routes served from a city, customer service, safety record, reputation, code-sharing relationships, frequent flier programs and redemption opportunities. Price competition occurs on a market-by-market basis through price discounts, changes in pricing structures, fare matching, target promotions and frequent flier initiatives. Airlines typically use discount fares and other promotions to stimulate traffic during normally slower travel periods to generate cash flow and to maximize unit revenue. The prevalence of discount fares can be particularly acute when a competitor has excess capacity that it is under financial pressure to sell.

In 2015, the airline industry saw greater and more persistent price discounting than in the preceding several years. A major reason enabling price discounting was the sharp decline in petroleum prices on world markets during the last couple years, which increased airline profitability and more than offset general increases in non-fuel costs. In addition, significant airline capacity increases in certain major cities - such as Dallas and Chicago - exerted strong downward price pressure in those markets. Finally, beginning in mid-2015 network carriers began seeking to match low-cost carrier and ULCC pricing on portions of their marginal unsold capacity, particularly in their key hub markets.

Absent significant increases in fuel prices and more constrained capacity, we expect the discounting trend to continue for the foreseeable future. Moreover, the network carriers have developed, or are in process of developing, a fare-class pricing approach, in which a portion of available seats may be sold at or near ULCC prices, but without most product features available to their passengers paying at higher fare levels on the same flight. Broad fare discounting can have the effect of diluting the profitability of revenues of network carriers, which have units costs significantly above those of ULCCs, but the fare-class approach may allow network carriers to continue offering a competitive price to ULCCs on some flights or routes, while maintaining higher pricing to their traditional constituencies of business and more affluent travelers.

Seasonality and Volatility. Our results of operations for any interim period are not necessarily indicative of those for the entire year because the air transportation business is subject to significant seasonal fluctuations. We generally expect demand to be greater in the second and third quarters compared to the rest of the year. The air transportation business is also volatile and highly affected by economic cycles and trends. Consumer confidence and discretionary spending, fear of terrorism or war, weakening economic conditions, fare initiatives, fluctuations in fuel prices, labor actions, changes in governmental regulations on taxes and fees, weather and other factors have resulted in significant fluctuations in revenues and results of operations in the past. We believe demand for business travel historically has been more sensitive to economic pressures than demand for low-price travel. Finally, a significant portion of our operations are concentrated in markets such as South Florida, the Caribbean, Latin America and the Northeast and northern Midwest regions of the United States, which are particularly vulnerable to weather, airport traffic constraints and other delays.

Aircraft Fuel. Fuel costs represent the single largest operating expense for most airlines, including ours. Fuel costs have been subject to wide price fluctuations in recent years. Fuel availability and pricing are also subject to refining capacity, periods of market surplus and shortage and demand for heating oil, gasoline and other petroleum products, as well as meteorological, economic and political factors and events occurring throughout the world, which we can neither control nor accurately predict. We source a significant portion of our fuel from refining resources located in the southeast United States, particularly facilities

adjacent to the Gulf of Mexico. Gulf Coast fuel is subject to volatility and supply disruptions, particularly in hurricane season when refinery shutdowns have occurred, or when the threat of weather-related disruptions has caused Gulf Coast fuel prices to spike above other regional sources. Our derivatives, from time to time, generally may consist of United States Gulf Coast jet fuel swaps (jet fuel swaps) and United States Gulf Coast jet fuel options (jet fuel options). Both jet fuel swaps and jet fuel options can be used at times to protect the refining price risk between the price of crude oil and the price of refined jet fuel, and to manage the risk of increasing fuel prices. Our fuel hedging practices are dependent upon many factors, including our assessment of market conditions for fuel, our access to the capital necessary to support margin requirements, the pricing of hedges and other derivative products in the market, our overall appetite for risk and applicable regulatory policies. As of December 31, 2015, we had no outstanding jet fuel derivatives. As of December 31, 2015, we purchased all of our aircraft fuel under a single fuel service contract. The cost and future availability of jet fuel cannot be predicted with any degree of certainty.

Labor. The airline industry is heavily unionized. The wages, benefits and work rules of unionized airline industry employees are determined by collective bargaining agreements, or CBAs. Relations between air carriers and labor unions in the United States are governed by the RLA. Under the RLA, CBAs generally contain “amendable dates” rather than expiration dates, and the RLA requires that a carrier maintain the existing terms and conditions of employment following the amendable date through a multi-stage and usually lengthy series of bargaining processes overseen by the NMB. This process continues until either the parties have reached agreement on a new CBA, or the parties have been released to “self-help” by the NMB. In most circumstances, the RLA prohibits strikes; however, after release by the NMB, carriers and unions are free to engage in self-help measures such as strikes and lockouts.

We have four union-represented employee groups comprising approximately 73% of our employees at December 31, 2015. Our pilots are represented by the Airline Pilots Association, International, or ALPA, our flight attendants are represented by the Association of Flight Attendants, or AFA-CWA, our flight dispatchers are represented by the Transport Workers Union of America, or TWU, and our ramp service agents are represented by the International Association of Machinists and Aerospace Workers, or IAMAW. Conflicts between airlines and their unions can lead to work slowdowns or stoppages. In June 2010, we experienced a five-day strike by our pilots, which caused us to shut down our flight operations. The strike ended as a result of our reaching a tentative agreement under a Return to Work Agreement and a full flight schedule was resumed on June 18, 2010. On August 1, 2010, we entered into a five-year collective bargaining agreement with our pilots. In August 2015, our CBA with our pilots became amendable and we are currently in discussions with ALPA regarding a new contract. In August 2013, we entered into a five-year agreement with our flight dispatchers. In August 2014, with the help of the NMB, we reached a tentative agreement for a five-year contract with our flight attendants. The tentative agreement was subject to ratification by the flight attendant membership. On October 1, 2014, we were notified that the flight attendants voted to not ratify the tentative agreement. We will continue to work together with the AFA-CWA and the NMB with a goal of reaching a mutually beneficial agreement. On July 8, 2014, certain ramp service agents directly employed by us voted to be represented by the IAMAW. In May 2015, we entered into a five-year interim collective bargaining agreement with the IAMAW, including material economic terms, and we are in the process of negotiating a final collective bargaining agreement with the IAMAW. We believe the five-year term of our CBAs is valuable in providing stability to our labor costs and provide us with competitive labor costs compared to other U.S.-based low-cost carriers. If we are unable to reach agreement with any of our unionized work groups in current or future negotiations regarding the terms of their CBAs, we may be subject to work interruptions or stoppages, such as the strike by our pilots in June 2010. A strike or other significant labor dispute with our unionized employees is likely to adversely affect our ability to conduct business. Any agreement we do reach could increase our labor and related expenses.

In 2010, the Patient Protection and Affordable Care Act was passed into law. While much of the cost of the healthcare legislation enacted will occur after 2015 due to provisions of the legislation being delayed and phased in over time, we expect changes to our healthcare cost structure could potentially increase our operating costs, with healthcare costs increasing at a higher rate than our employee headcount.

Maintenance Expense. Maintenance expense grew through 2015, 2014 and 2013 mainly as a result of a growing fleet and the gradual increase of required maintenance for the older aircraft in our fleet. As the fleet ages, we expect that maintenance costs will increase in absolute terms. The amount of total maintenance costs and related amortization of heavy maintenance (included in depreciation and amortization expense) is subject to many variables such as future utilization rates, average stage length, the interval between heavy maintenance events, the size and makeup of the fleet in future periods and the level of unscheduled maintenance events and their actual costs. Accordingly, we cannot reliably quantify future maintenance expenses for any significant period of time. However, we believe, based on our scheduled maintenance events, maintenance expense and maintenance-related amortization expense in 2016 will be approximately $164 million. In addition, we expect to capitalize $92 million of costs for heavy maintenance during 2016.

As a result of a significant portion of our fleet being acquired over a relatively short period of time, heavy maintenance scheduled on each of our planes will occur at roughly the same time, meaning we will incur our most expensive

scheduled maintenance obligations across our current fleet around the same time. These more significant maintenance activities will result in out-of-service periods during which our aircraft will be dedicated to maintenance activities and unavailable to fly revenue service. When accounting for maintenance expense under the deferral method, heavy maintenance is amortized over the shorter of either the remaining lease term or the next estimated heavy maintenance event. As a result, deferred maintenance events occurring closer to the end of the lease term will generally have shorter amortization periods than those occurring earlier in the lease term. This will create higher depreciation and amortization expense specific to any aircraft related to heavy maintenance during the final years of the lease as compared to earlier periods. Please see “— Critical Accounting Policies and Estimates-Aircraft Maintenance, Materials, Repair Costs and Related Heavy Maintenance Amortization.”

Maintenance Reserve Obligations. The terms of some of our aircraft lease agreements require us to post deposits for future maintenance, also known as maintenance reserves, to the lessor in advance of and as collateral for the performance of major maintenance events, resulting in our recording significant prepaid deposits on our balance sheet. As a result, the cash costs of scheduled major maintenance events are paid in advance of the recognition of the maintenance event in our results of operations. Please see “—Critical Accounting Policies and Estimates—Aircraft Maintenance, Materials, Repair Costs and Related Heavy Maintenance Amortization” and “—Maintenance Reserves.”

Critical Accounting Policies and Estimates

The following discussion and analysis of our financial condition and results of operations is based on our financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States. The preparation of these financial statements requires us to make estimates and judgments that affect the reported amount of assets and liabilities, revenues and expenses and related disclosure of contingent assets and liabilities at the date of our financial statements. For a detailed discussion of our significant accounting policies, please see “Notes to Financial Statements—1. Summary of Significant Accounting Policies.”

Critical accounting policies are defined as those policies that reflect significant judgments or estimates about matters both inherently uncertain and material to our financial condition or results of operations.

Revenue Recognition. Revenues from tickets sold are initially deferred as ATL. Passenger revenues are recognized when transportation is provided. An unused non-refundable ticket expires at the date of scheduled travel and is recognized as revenue for the expired ticket value at the date of scheduled travel.

Our most significant non-ticket revenues include revenues generated from air travel-related services paid for baggage, passenger usage fees, advance seat selection, itinerary changes, and loyalty programs. The majority of our non-ticket revenues are recognized once the related flight departs. Some of our non-ticket revenues, such as those related to itinerary changes, are recognized at the time products are purchased or services are provided. These revenues also include commissions from the sales of hotel rooms, trip insurance and rental cars recognized at the time the service is rendered. Non-ticket revenues also include revenues from our subscription-based $9 Fare Club, recognized on a straight-line basis over 12 months.

Customers may elect to change their itinerary prior to the date of departure. A service charge is assessed and recognized on the date the change is initiated and is deducted from the face value of the original purchase price of the ticket, and the original ticket becomes invalid. The amount remaining after deducting the service charge is called a credit shell which expires 60 days from the date the credit shell is created and can be used towards the purchase of a new ticket and our other service offerings. The amount of credits expected to expire unused is recognized as revenue upon issuance of the credit and is estimated based on historical experience. Estimating the amount of credits that will go unused involves some level of subjectivity and judgment.

Frequent Flier Program. We accrue for mileage credits earned through travel, including mileage credits for members with an insufficient number of mileage credits to earn an award, under our FREE SPIRIT program based on the estimated incremental cost of providing free travel for credits that are expected to be redeemed. Incremental costs include fuel, insurance, security, ticketing and facility charges reduced by an estimate of amounts required to be paid by the passenger when redeeming the award.

Under our affinity card program, funds received for the marketing of a co-branded Spirit credit card and delivery of award miles are accounted for as a multiple-deliverable arrangement. At the inception of the arrangement, we evaluated all deliverables in the arrangement to determine whether they represent separate units of accounting. We determined the arrangement had three separate units of accounting: (i) travel miles to be awarded, (ii) licensing of brand and access to member lists and (iii) advertising and marketing efforts. At inception of the arrangement, we established the estimated selling price for all deliverables that qualified for separation, as arrangement consideration should be allocated based on relative selling price. The manner in which the selling price was established was based on the applicable hierarchy of evidence. Total arrangement consideration was then allocated to each deliverable on the basis of the deliverable's relative selling price. In considering the

hierarchy of evidence, we first determined whether vendor-specific objective evidence of selling price or third-party evidence of selling price existed. We determined that neither vendor-specific objective evidence of selling price nor third-party evidence existed due to the uniqueness of our program. As such, we developed our best estimate of the selling price for all deliverables. For the selling price of travel, we considered a number of entity-specific factors including the number of miles needed to redeem an award, average fare of comparable segments, breakage, restrictions, fees to redeem miles and other charges. For licensing of brand and access to member lists, we considered both market-specific factors and entity-specific factors, including general profit margins realized in the marketplace/industry, brand power, market royalty rates and size of customer base. For the advertising and marketing element, we considered market-specific factors and entity-specific factors including, our internal costs (and fluctuations of costs) of providing services, volume of marketing efforts and overall advertising plan. Consideration allocated based on the relative selling price to both brand licensing and advertising elements is recognized as revenue when earned and recorded in non-ticket revenue. Consideration allocated to award miles is deferred and recognized ratably as passenger revenue over the estimated period the transportation is expected to be provided which is currently estimated at 14 months. We used entity-specific assumptions coupled with the various judgments necessary to determine the selling price of a deliverable in accordance with the required selling price hierarchy. Changes in these assumptions could result in changes in the estimated selling prices. Determining the frequency to reassess selling price for individual deliverables requires significant judgment. For additional information, please see “Notes to Financial Statements—1. Summary of Significant Accounting Policies—Frequent Flier Program”.

Accounting for property and equipment. Property and equipment is stated at cost, less accumulated depreciation and amortization. Depreciation of operating property and equipment is computed using the straight-line method applied to each unit of property. Property under capital leases and related obligations are initially recorded at an amount equal to the present value of future minimum lease payments computed using our incremental borrowing rate or, when known, the interest rate implicit in the lease. Amortization of property under capital leases is on a straight-line basis over the lease term and is included in depreciation and amortization expense. In accounting for property and equipment, we must make estimates about the expected useful lives of the assets, the expected residual values of the assets, and the potential for impairment based on the fair value of the assets and their future expected cash flows.

The depreciable lives used for the principal depreciable asset classifications are:



	Estimated Useful Life
Aircraft	25 years
Spare rotables and flight assemblies	7 to 15 years
Other equipment and vehicles	5 to 7 years
Internal use software	3 to 10 years
Capital lease	Lease term
Leasehold improvements	Lesser of lease term or estimated useful life of the improvement

As of December 31, 2015, we had 18 aircraft capitalized within flight equipment with depreciable lives of 25 years and 61 aircraft financed through operating leases with terms of 3 to 15 years. All spare engines are financed through operating leases with terms of 7 to 12 years. Residual values for aircraft, major spare rotable parts, avionics and assemblies are estimated to be 10%.

We record impairment charges on long-lived assets used in operations when events and circumstances indicate the assets may be impaired, the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets, and the net book value of the assets exceeds their estimated fair value. In making these determinations, we use certain assumptions, including, but not limited to: (i) estimated fair value of the assets; and (ii) estimated, undiscounted future cash flows expected to be generated by these assets, which are based on additional assumptions such as asset utilization, length of service the asset will be used in our operations, and estimated salvage values.

Aircraft Maintenance, Materials, Repair Costs and Related Heavy Maintenance Amortization. We account for heavy maintenance under the deferral method. Under the deferral method the cost of heavy maintenance is capitalized and amortized as a component of depreciation and amortization expense over the earlier of the next estimated heavy maintenance event or the remaining lease term or useful life of the aircraft. Management expects that heavy maintenance events occurring closer to the end of the lease term will be amortized over the remaining lease term rather than over the next estimated heavy maintenance event. Amortization of engine and aircraft overhaul costs was $43.1 million, $35.8 million and $23.6 million for the years ended December 31, 2015, 2014 and 2013, respectively. If heavy maintenance costs were amortized within maintenance, material and repairs expense in the statement of operations, our maintenance, material and repairs expense would have been

$123.6 million, $109.8 million and $83.8 million for the years ended December 31, 2015, 2014 and 2013, respectively. During the years ended December 31, 2015, 2014 and 2013, we capitalized $9.1 million, $33.6 million and $70.8 million of costs for heavy maintenance, respectively. The timing of the next heavy maintenance event is estimated based on assumptions including estimated usage, FAA-mandated maintenance intervals, current condition of the related component, the age of the related component and average removal times as suggested by the manufacturer. These assumptions may change based on changes in our utilization of our aircraft, changes in government regulations and suggested manufacturer maintenance intervals. In addition, these assumptions can be affected by unplanned incidents that could damage an airframe, engine or major component to a level that would require a heavy maintenance event prior to a scheduled maintenance event. To the extent the estimated timing of the next maintenance event is extended or shortened, the related amortization period would be lengthened or shortened, resulting in higher amortization expense over a shorter period or lower amortization expense over a longer period, respectively. Heavy maintenance events include 6-year and 12-year airframe checks, engine overhauls, LLP replacement and overhauls to major components. Certain maintenance functions are outsourced under contracts that require payment based on a performance measure such as flight hours. Costs incurred for maintenance and repair under flight hour maintenance contracts, where labor and materials price risks have been transferred to the service provider, are accrued based on contractual payment terms. Routine cost for maintaining the airframes and engines and line maintenance are charged to maintenance, materials and repairs expense as performed.

Maintenance Reserves. Some of our master lease agreements provide that we pay maintenance reserves to aircraft lessors to be held as collateral in advance of our performance of major maintenance activities. These lease agreements provide that maintenance reserves are reimbursable to us upon completion of the maintenance event in an amount equal to either (1) the amount of the maintenance reserve held by the lessor associated with the specific maintenance event or (2) the qualifying costs related to the specific maintenance event. Substantially all of these maintenance reserve payments are calculated based on a utilization measure, such as flight hours or cycles and are used solely to collateralize the lessor for maintenance time run off the aircraft until the completion of the maintenance of the aircraft.

At lease inception and at each balance sheet date, we assess whether the maintenance reserve payments required by the master lease agreements are substantively and contractually related to the maintenance of the leased asset. Maintenance reserve payments that are substantively and contractually related to the maintenance of the leased asset are accounted for as maintenance deposits. Maintenance deposits expected to be recovered from lessors are reflected as aircraft maintenance deposits in the accompanying balance sheets. We make certain assumptions to determine the recoverability of maintenance deposits. These assumptions are based on various factors such as the estimated time between the maintenance events, the cost of future maintenance events and the number of flight hours the aircraft is estimated to be utilized before it is returned to the lessor. When it is not probable we will recover amounts currently on deposit with a lessor, such amounts are expensed as supplemental rent. We expensed $2.3 million, $1.6 million and $1.9 million of paid maintenance reserves as supplemental rent during 2015, 2014 and 2013, respectively.

As of December 31, 2015 and 2014, we had aircraft maintenance deposits of $279.9 million and $250.0 million, respectively, on our balance sheets. We have concluded that these aircraft maintenance deposits are probable of recovery primarily due to the rate differential between the maintenance reserve payments and the expected cost for the related next maintenance event that the reserves serve to collateralize.

The master lease agreements also provide that most maintenance reserves held by the lessor at the expiration of the lease are nonrefundable to us and will be retained by the lessor. Consequently, we have determined that any usage-based maintenance reserve payments after the last major maintenance event are not substantively related to the maintenance of the leased asset and therefore are accounted for as contingent rent. Contingent rent is recorded at the time a non-refundable maintenance reserve payment is made that has been substantively determined to be contingent rent. Accordingly, management expects to incur contingent rent after the last major maintenance events resulting in higher rent expense in the final years of applicable leases. Maintenance reserves held by lessors that are refundable to us at the expiration of the lease are accounted for as aircraft maintenance deposits on the balance sheet when they are paid.

Leased Aircraft Return Costs. Our aircraft lease agreements often contain provisions that require us to return aircraft airframes and engines to the lessor in a certain condition or pay an amount to the lessor based on the airframe and engine's actual return condition. Lease return costs include all costs that would be incurred at the return of the aircraft including costs incurred to repair the airframe and engines to the required condition as stipulated by the lease. Lease return costs could include, but are not limited to redelivery cost, redelivery crew cost, fuel, final inspections, reconfiguration of the cabin, repairs to the airframe, painting, overhaul of engines, replacement of components and checks. Lease return costs are recognized beginning when it is probable that such costs will be incurred and they can be estimated. Incurrence of lease return costs becomes probable and the amount of those costs can typically be estimated near the end of the lease term (that is, after the aircraft has completed its last maintenance cycle prior to being returned). When determining probability and estimated cost, there are various factors which need to be considered such as current condition of the aircraft, the age of the aircraft at lease expiration,

number of hours run on the engines, number of cycles run on the airframe, projected number of hours run on the engine at the time of return, number of projected cycles run on the airframe at the time of return, the extent of repairs needed if any at return, return locations, current configuration of the aircraft, current paint of the aircraft, estimated escalation of cost of repairs and materials at the time of return, current flight hour agreement rates and future flight hour agreement rates. In addition, typically near the lease return date, the lessors may allow reserves to be applied as return condition consideration or pass on certain return provisions if they do not align with their current plans to remarket the aircraft. When costs become both probable and estimable, they are accrued on a straight-line basis as contingent rent, a component of supplemental rent, through the remaining lease term. Management expects return costs to be estimable near the end of the lease term, as such, contingent rent for related aircraft will be higher near the end of the lease term.

Results of Operations

In 2015, we generated operating revenues of $2,141.5 million and operating income of $509.1 million resulting in a record 23.8% operating margin and net earnings of $317.2 million. In 2014, we generated operating revenues of $1,931.6 million and operating income of $355.3 million resulting in an 18.4% operating margin and net earnings of $225.5 million. Operating revenues increased year over year mainly as a result of a 27.1% increase in traffic. Increased operations resulted in higher operating expenses across the board which were mostly offset with a significant decrease in fuel costs due to lower fuel cost per gallon.

As of December 31, 2015, our cash and cash equivalents grew to $803.6 million, an increase of $170.8 million compared to the prior year, mainly driven by cash from our operating activities offset by cash used to fund PDPs, capital expenditures and repurchases of common stock.

Operating Revenues



	Year Ended 2015		% change 2015 versus 2014	Year Ended 2014		% change 2014 versus 2013	Year Ended 2013
Passenger (thousands)	$	1,169,338	2.1%	$	1,144,972	16.1%	$	986,018
Non-ticket (thousands)	972,125		23.6%	786,608		17.7%	668,367
Total operating revenue (thousands)	$	2,141,463	10.9%	$	1,931,580	16.8%	$	1,654,385
Total operating revenue per ASM (TRASM) (cents)	10.08		(14.7)%	11.82		(1.0)%	11.94
Average ticket revenue per passenger flight segment	$	65.25	(18.5)%	$	80.11	0.9%	$	79.43
Average non-ticket revenue per passenger flight segment	54.24		(1.4)%	55.03		2.2%	53.84
Total revenue per passenger flight segment	$	119.49	(11.6)%	$	135.14	1.4%	$	133.27

2015 compared to 2014

Operating revenues increased by $209.9 million, or 10.9%, to $2,141.5 million in 2015 compared to 2014, primarily due to an increase in traffic of 27.1%, partially offset by a decrease in average yield of 12.8% to 11.90 cents. The decrease in average yield resulted from increased competitive pressures from major domestic network carriers aggressively discounting fare prices.

TRASM for 2015 was 10.08 cents, a decrease of 14.7% compared to 2014, as a result of lower operating yields on relatively stable load factors. Total revenue per passenger flight segment decreased 11.6% from $135.14 in 2014 to $119.49 in 2015. The year-over-year decrease in total revenue per passenger flight segment was driven by a decrease of 18.5% in ticket revenue per passenger flight segment, resulting from the increased competitive pressures noted during the period.

During 2015, our average non-ticket revenue per passenger flight segment remained relatively stable, declining by 1.4%, or $0.79, to $54.24, despite the increased competitive pressures. Our unbundling model provides a more stable revenue stream as demonstrated during periods of lower passenger ticket yields. The decrease in non-ticket revenue per passenger flight segment was primarily attributable to lower bag revenue and the outsourcing of our onboard catering to a third-party provider. The outsourcing of onboard catering resulted in improved operating margins. These declines, contributing to the decrease in non-ticket revenue, were partially offset by higher per segment convenience charges compared to the same period last year.

2014 compared to 2013

Operating revenues increased by $277.2 million, or 16.8%, to $1,931.6 million in 2014 compared to 2013, primarily due to an increase in traffic of 18.0%, offset slightly by a decrease in average yield of 1.1% to 13.64 cents.

Our results for 2014 were driven by a capacity increase of 17.9% compared to 2013, while maintaining a high load factor of 86.7%. TRASM for 2014 was 11.82 cents, a decrease of 1.0% compared to 2013, as a result of lower operating yields on relatively stable load factors. Total revenue per passenger flight segment increased 1.4% from $133.27 in 2013 to $135.14 in 2014. The year-over-year increase in total revenue per passenger flight segment is due to higher non-ticket revenue per passenger flight segment offset by lower ticket revenue per passenger flight segment.

During 2014, we increased our average non-ticket revenue per passenger flight segment by 2.2%, or $1.19, to $55.03. Our total non-ticket revenue increased by 17.7%, or $118.2 million, to $786.6 million in 2014. The year-over-year increase in average non-ticket revenue per passenger flight segment was primarily driven by a higher volume of passengers electing to purchase seat assignments, largely due to a software update completed in 2014 that enables us to sell seat assignments through more channels as well as a more rigorous approach to managing our seat inventory. Additionally, in July 2013, we increased our passenger usage fee (PUF), helping to drive the increase in PUF fees year over year.

Operating Expenses

Since adopting our ULCC model, we have continuously sought to reduce our unit operating costs and have created one of the industry's lowest cost structures in the United States. The table below presents our operating expenses, as a percentage of operating revenue for the last three years, as well as unit operating costs (CASM).



	Year Ended December 31,
	2015					2014					2013
	% of Revenue		CASM			% of Revenue		CASM			% of Revenue		CASM
Operating revenue	100.0	%				100.0	%				100.0	%
Operating expenses:
Aircraft fuel (1)	21.5	%		2.17	¢	31.7	%		3.75	¢	33.4	%		3.98	¢
Salaries, wages and benefits	17.7		1.78			16.3		1.92			15.8		1.89
Aircraft rent	9.9		1.00			10.1		1.20			10.3		1.22
Landing fees and other rentals	6.1		0.62			5.4		0.64			5.1		0.60
Distribution	4.0		0.41			3.9		0.46			4.1		0.49
Maintenance, materials and repairs	3.8		0.38			3.8		0.45			3.6		0.43
Depreciation and amortization	3.5		0.35			2.4		0.29			1.9		0.23
Other operating expenses	9.7		0.97			7.7		0.92			8.7		1.04
Loss on disposal of assets	0.1		0.01			0.2		0.02			—		—
Special charges	—		—			—		—			—		—
Total operating expense	76.2	%				81.6	%				82.9	%
CASM				7.68	¢				9.65	¢				9.90	¢
Adjusted CASM (2)			7.69					9.55					9.89
Adjusted CASM ex fuel (3)			5.50					5.88					5.91


(1)	Aircraft fuel expense is the sum of (i) “into-plane fuel cost,” which includes the cost of jet fuel and certain other charges such as fuel taxes and oil, (ii) realized gains and losses related to fuel derivative contracts and (iii) unrealized gains and losses related to fuel derivative contracts. The following table summarizes the components of aircraft fuel expense for the periods presented:



	Year Ended December 31,
	2015			2014		2013
	(in thousands)
Into-plane fuel cost	$	454,747		$	608,033	$	542,523
Realized losses (gains) related to fuel derivative contracts, net	10,580			995		8,958
Unrealized losses (gains) related to fuel derivative contracts, net	(3,880		)	3,881		265
Aircraft fuel	$	461,447		$	612,909	$	551,746

(2)Reconciliation of CASM to Adjusted CASM:



	Year Ended December 31,
	2015					2014			2013
	(in millions)			Per ASM		(in millions)		Per ASM	(in millions)		Per ASM
CASM (cents)				7.68				9.65			9.90
Unrealized losses (gains) related to fuel derivative contracts	$	(3.9	)	(0.02	)	$	3.9	0.02	$	0.3	—
Loss on disposal of assets	1.6			0.01		3.0		0.02	0.5		—
Special charges	0.7			—		—		—	0.2		—
Out of period fuel excise tax	—			—		9.3		0.06	—		—
Adjusted CASM (cents)				7.69				9.55			9.89


(3)	Excludes aircraft fuel expense, loss on disposal of assets, and special charges.

2015 compared to 2014

Operating expense increased by $56.0 million, or 3.6%, in 2015 primarily due to our 30.0% growth in capacity which drove increases in operating expenses offset almost entirely by a significant decrease in fuel cost per gallon.

Our adjusted CASM ex fuel for 2015 decreased by 6.5% as compared to 2014. The decrease on a per-ASM basis was primarily due to a decrease in aircraft rent and labor costs. The decrease in our aircraft rent per ASM is related to the recent purchase of aircraft with lower ownership costs recorded under depreciation and amortization versus leased aircraft recorded under aircraft rent. This decrease in aircraft rent was partially offset by higher depreciation and amortization expense related to the depreciation of our recently purchased aircraft. Labor costs per ASM are lower in 2015, as compared to the prior period, primarily due to scale benefits from overall growth as well as from larger gauge aircraft.

Aircraft fuel expenses includes both into-plane expense (as defined below) and realized and unrealized net gains or losses from fuel derivatives. Into-plane fuel expense is defined as the price that we generally pay at the airport, or the “into-plane” price, including taxes and fees. Into-plane fuel prices are affected by the global oil market, refining costs, transportation taxes and fees, which can vary by region in the United States and other countries where we operate. Into-plane fuel expense approximates cash paid to the supplier and does not reflect the effect of our fuel derivatives. Management chose not to elect hedge accounting on any fuel derivative instruments during 2015, 2014 or 2013 and, as a result, changes in the fair value of these fuel derivative contracts are recorded each period as a component of aircraft fuel expense.

During the third quarter of 2014, we became aware of an underpayment of Federal Excise Tax (FET) for fuel purchases during the period between July 1, 2009 and August 31, 2014. An out of period jet fuel FET amount of $9.3 million is recorded within aircraft fuel in the statement of operations for the year ended December 31, 2014.

Aircraft fuel expense, our largest operating cost as a percentage of operating expenses, decreased by 24.7% from $612.9 million in 2014 to $461.4 million in 2015. The decrease was primarily due to a 39.1% decrease in fuel prices per gallon, partially offset by a 27.2% increase in fuel gallons consumed.

The elements of the changes in aircraft fuel expense are illustrated in the following table:



	Year Ended December 31,
	2015			2014
	(in thousands, except per gallon amounts)					Percent Change
Fuel gallons consumed	255,008			200,498		27.2	%
Into-plane fuel cost per gallon	$	1.78		$	3.03	(41.3	)%
Into-plane fuel expense	$	454,747		$	608,033	(25.2	)%
Realized losses (gains) related to fuel derivative contracts, net	10,580			995		NM
Unrealized losses (gains) related to fuel derivative contracts, net	(3,880		)	3,881		NM
Aircraft fuel expense (per statement of operations)	$	461,447		$	612,909	(24.7	)%

Gulf Coast Jet indexed fuel is the basis for a substantial majority of our fuel consumption and is impacted by both the price of crude oil as well as increases or decreases in refining margins associated with the conversion of crude oil to jet fuel. The into-plane fuel cost per gallon decrease of 41.3% was primarily a result of a decrease in jet fuel prices.

In 2015, we recognized $10.6 million of realized loss related to fuel derivatives consisting of $11.2 million of premiums paid for fuel options that expired during the twelve months ended December 31, 2015 offset by $0.6 million of cash received from fuel options that settled during the period. In 2014, total realized loss related to fuel derivatives was $1.0 million which represents premiums paid for fuel options that expired during the twelve months ended December 31, 2014. There was no cash received from fuel options that settled during 2014. During the twelve months ended December 31, 2015 and December 31, 2014, we paid $2.5 million and $9.7 million, respectively, in premiums to acquire fuel options. We had unrealized gains of $3.9 million and unrealized losses of $3.9 million related to mark to market adjustments in the fair value of our outstanding fuel derivatives during the twelve months ended December 31, 2015 and December 31, 2014, respectively.

We track economic fuel expense, which we believe is the best measure of the effect fuel prices are currently having on our business, because it most closely approximates the net cash outflow associated with purchasing fuel used for our operations during the period. We define economic fuel expense as into-plane fuel expense and realized gains or losses on derivative contracts. The key difference between aircraft fuel expense, as recorded in our statement of operations, and economic fuel expense is unrealized mark-to-market changes in the value of aircraft fuel derivatives outstanding. In addition, in our calculation for economic fuel price for the prior year, we are excluding the out of period additional jet fuel FET amount of $9.3 million expensed in the third quarter of 2014. Many industry analysts evaluate airline results using economic fuel expense and it is used in our internal management reporting.

The elements of the changes in economic fuel expense are illustrated in the following table:



	Year Ended December 31,
	2015		2014
	(in thousands, except per gallon amounts)					Percent Change
Into-plane fuel expense	$	454,747	$	608,033		(25.2	)%
Realized (gains) and losses related to fuel derivative contracts, net	10,580		995			NM
Out of period fuel federal excise tax	—		(9,278		)	NM
Economic fuel expense	$	465,327	$	599,750		(22.4	)%
Fuel gallons consumed	255,008		200,498			27.2	%
Economic fuel cost per gallon	$	1.82	$	2.99		(39.1	)%

Fuel gallons consumed increased 27.2% as a result of increased operations, as evidenced by a 26.4% increase in block hours.

Labor costs in 2015 increased by $64.2 million, or 20.5%, compared to 2014, due mainly to a 27.9% increase in our pilot and flight attendant workforce required to operate the 14 new aircraft deliveries in 2015, offset slightly by a decrease in bonus expense due to a failure to achieve bonus targets in 2015. On a per-ASM basis, labor costs decreased primarily due to scale benefits from overall growth and lower bonus expense on both a dollar and per ASM basis, offset slightly by rising health care costs which rose more than our capacity growth during the year.

During 2015, aircraft rent increased $15.7 million, or 8.0%, compared to 2014. This increase was primarily driven by a full year's rent of the seven leased aircraft delivered throughout 2014. We did not take delivery of any leased aircraft during 2015. On a per-ASM basis, aircraft rent expense decreased due to a change in composition of our aircraft fleet between leased aircraft (for which rent expense is recorded under aircraft rent) and purchased aircraft (for which depreciation expense is recorded under depreciation and amortization). Since the prior year period, we have purchased and taken delivery of 14 aircraft, which increased capacity but had no effect on aircraft rent expense, as these assets were purchased and are being depreciated over their useful life. Had the respective aircraft been leased, the change in rent expense, on both a dollar and per-ASM basis, would have been greater than the increase currently experienced in depreciation and amortization as a result of these purchases.

Landing fees and other rents for 2015 increased by $26.0 million, or 24.7%, compared to 2014 driven by increased flight volume. On a per-ASM basis, landing fees and other rents decreased slightly, year over year, primarily due to scale benefits from increased volume at our airports.

The increase in distribution expense of $11.8 million, or 15.7%, in 2015 compared to 2014 was primarily due to increased sales volume. On a per-ASM basis, distribution expense decreased primarily due to a decrease in credit card fees resulting from a renegotiation with our primary credit card processor in late 2014 and a slight shift of sales from third-party travel agents to our website.

The following table shows our distribution channel usage:



	Year Ended December 31,
	2015		2014		Change
Website	63.5	%	61.1	%	2.4
Third-party travel agents	32.0		34.4		(2.4	)
Call center	4.5		4.5		—

Maintenance, materials and repair costs increased by $6.5 million, or 8.8%, in 2015, as compared to 2014 . The increase in maintenance costs on a dollar basis was due to routine and ongoing maintenance on a growing fleet. On a per-unit basis, our growth outpaced the increase in maintenance costs during the period, as compared to the prior year period. In addition, the timing and mix of maintenance events resulted in lower cost events in the current year period as compared to the prior year period. On a per-unit basis, maintenance expense decreased due to the purchase of $13.0 million in rotable inventory that was made in the third quarter of 2014 to support our aircraft fleet. The expense for these rotables is recorded under depreciation and amortization expense instead of maintenance expense as in the prior year period when the rotables were leased from a third party. We expect maintenance expense to increase as our fleet continues to grow and age, resulting in the need for additional or more frequent repairs over time.

Depreciation and amortization increased by $26.9 million, or 57.3%, compared to the prior year period. The increase on both a dollar and per-ASM basis was primarily due to depreciation expense resulting from the purchase of 14 aircraft made during 2015.

Other operating expenses in 2015 increased by $57.2 million, or 38.2%, compared to 2014, primarily due to an increase in departures of 25.6%, our overall growth and an increase in passenger re-accommodation expense year over year. On a per-ASM basis, our other operating expenses increased primarily due to higher passenger re-accommodation expense. Re-accommodation expense was driven by an increased number of flight cancellations, as compared to the same period last year. For example, during the second quarter of 2015, we experienced consecutive storm systems in Dallas, Chicago, New York, and Detroit followed by Tropical Storm Bill that sat over Houston before moving north to Dallas. The timing and location of these storm systems produced a domino effect on our operations resulting in over 500 flight cancellations and numerous flight delays. Our travel and lodging expense was also higher, as compared to the prior year period, due to increased operations, the training of new pilots and flight attendants, and higher average lodging rates.

2014 compared to 2013

Operating expense increased by $204.2 million, or 14.9%, in 2014 primarily due to our 17.9% growth in capacity as well as higher amortization of heavy maintenance events on our aircraft.

Our adjusted CASM ex fuel for 2014 decreased by 0.5% as compared to 2013. The decrease was primarily due to lower passenger re-accommodation expense year over year, due to better operational performance during 2014, as compared to 2013. In addition, on a per-ASM basis, distribution expense decreased, primarily due to a $2.9 million settlement gain received in 2014, and aircraft rent expense decreased due to reduced rent expense related to 14 A319 aircraft for which lease extensions with reduced rates were negotiated with the lessor at the end of the second quarter of 2013, providing for a full year of benefit in 2014 versus 7 months of benefit in 2013. These decreases were partially offset by an increase in depreciation and amortization expense, landing fees and other rents expense, salaries, wages and benefits expense, and maintenance, materials and repairs expense per ASM.

Aircraft fuel expense increased by 11.1% from $551.7 million in 2013 to $612.9 million in 2014. The increase was primarily due to a 16.6% increase in fuel gallons consumed as well as an additional $9.3 million recorded in the third quarter of 2014 for unpaid jet fuel FET related to prior years, partially offset by a 6.9% decrease in fuel prices per gallon.

The elements of the changes in aircraft fuel expense are illustrated in the following table:



	Year Ended December 31,
	2014		2013
	(in thousands, except per gallon amounts)				Percent Change
Fuel gallons consumed	200,498		171,931		16.6	%
Into-plane fuel cost per gallon	$	3.03	$	3.16	(4.1	)%
Into-plane fuel expense	$	608,033	$	542,523	12.1	%
Realized losses (gains) related to fuel derivative contracts, net	995		8,958		NM
Unrealized losses (gains) related to fuel derivative contracts, net	3,881		265		NM
Aircraft fuel expense (per statement of operations)	$	612,909	$	551,746	11.1	%

The into-plane fuel cost per gallon decrease of 4.1% was primarily a result of a decrease in jet fuel prices partially offset by an additional $9.3 million for prior year unpaid jet fuel FET recorded in the third quarter of 2014.

The elements of the changes in economic fuel expense are illustrated in the following table:



	Year Ended December 31,
	2014			2013
	(in thousands, except per gallon amounts)					Percent Change
Into-plane fuel expense	$	608,033		$	542,523	12.1	%
Realized (gains) and losses related to fuel derivative contracts, net	995			8,958		NM
Out of period fuel federal excise tax	(9,278		)	—		NM
Economic fuel expense	$	599,750		$	551,481	8.8	%
Fuel gallons consumed	200,498			171,931		16.6	%
Economic fuel cost per gallon	$	2.99		$	3.21	(6.9	)%

Fuel gallons consumed increased 16.6% as a result of increased operations, as evidenced by a 15.6% increase in block hours.

We did not pay or receive cash from any fuel derivatives that settled during the twelve months ended December 31, 2014. Total net loss recognized for derivatives that settled during the twelve months ended December 31, 2013 was $9.0 million. This amount represents the net cash paid for the settlement of derivatives. We paid $1.0 million in premiums for fuel options which expired during the twelve months ended December 31, 2014. We did not have any fuel options expire during the twelve months ended December 31, 2013. We had $3.9 million in unrealized gains and losses related to our outstanding fuel derivatives during

the twelve months ended December 31, 2014. Total unrealized losses arising from mark-to-market adjustments to our outstanding fuel derivatives for the twelve months ended December 31, 2013 was $0.3 million.

Labor costs in 2014 increased by $51.8 million, or 19.8%, compared to 2013, due mainly to a 19.1% increase in our pilot and flight attendant workforce required to operate the eleven new aircraft deliveries in 2014 and the implementation of new crew duty and rest rules (FAR 117) beginning in January of 2014, which resulted in the hiring of additional pilots to fly our schedule. On a per-ASM basis, labor costs increased primarily due to an increase in our group health care costs and the implementation of FAR 117, which resulted in carrying a higher ratio of pilots compared to the prior period.

During 2014, aircraft rent increased $26.1 million, or 15.4%, compared to 2013. This increase was primarily driven by the delivery of seven new leased aircraft during 2014. On a per-ASM basis, aircraft rent expense decreased due to lease extensions that effectively lowered the lease rate for 14 A319 aircraft at the end of the second quarter of 2013, providing for a full year of benefit in 2014 versus 7 months of benefit in 2013. In addition, we had the delivery of four purchased aircraft during the fourth quarter of 2014 that increased capacity but had no affect on aircraft rent expense as these assets are being depreciated over their useful life.

Landing fees and other rents for 2014 increased by $21.5 million, or 25.7%, compared to 2013 primarily due to a 13.6% increase in departures as well as increased volume at higher cost airports. On a per-ASM basis, landing fees and other rents increased, as compared to the prior year period, due to increased rates at certain airports, expiration of incentives, as well as increased volume at higher-cost airports.

The increase in distribution expense of $7.3 million, or 10.9%, in 2014 compared to 2013 was primarily due to increased sales volume and an increase of approximately 0.9 percentage points, year over year, in sales from third-party travel agents, which are more expensive than selling directly through our website. On a per-ASM basis, distribution expense decreased primarily due to a $2.9 million settlement gain received in 2014.

The following table shows our distribution channel usage:



	Year Ended December 31,
	2014		2013		Change
Website	61.1	%	61.0	%	0.1
Third-party travel agents	34.4		33.5		0.9
Call center	4.5		5.5		(1.0	)

Maintenance, materials and repair costs increased by $13.8 million, or 23.0%, in 2014, as compared to 2013. The increase in maintenance costs was primarily due to the aging of our fleet, which requires more comprehensive work during routine scheduled maintenance, as well as the timing of the mix of maintenance checks performed during 2014 as compared to 2013. In addition, during the third quarter of 2014, we recorded $2.3 million of expense in connection with an engine failure incident that occurred in 2013. For a detailed discussion of the engine expense, please see “Notes to the Financial Statements—1. Summary of Significant Accounting Policies.”. In addition, the increase in maintenance costs on a dollar basis and per unit basis resulted from an increase in both the number and cost of scheduled maintenance events during the year ended December 31, 2014, as compared to the prior year. We expect maintenance expense to increase significantly as our fleet continues to grow and age, resulting in the need for additional or more frequent repairs over time.

Depreciation and amortization increased by $15.0 million, or 47.0%, primarily due to higher amortization of deferred heavy maintenance. As our fleet continues to age, the amount of deferred heavy maintenance events capitalized will increase and will result in an increase in the amortization of those costs.

Other operating expenses in 2014 increased by $5.1 million, or 3.5%, compared to 2013 primarily due to an increase in departures of 13.6% and our overall growth. On a per-ASM basis, our other operating expenses decreased, as compared to the same period in 2013, due to lower passenger re-accommodation expense resulting from improved operational reliability.

Other (income) expense, net

2015 compared to 2014

Other (income) expense, net increased from $2.3 million in 2014 to $6.7 million in 2015. This increase was primarily driven by an increase in interest expense of $17.6 million, which primarily represented interest related to the financing of purchased aircraft, offset by an increase in the capitalization of interest of $8.8 million. Additionally, interest income increased by $1.8 million, year over year, as we earned interest income on funds required to be held in escrow in accordance with the terms of our EETC. See “Notes to the Financial Statements—9. Debt and Other Obligations” for additional information.

2014 compared to 2013

Other (income) expense, net decreased from $(0.1) million in 2013 to $2.3 million in 2014. The decrease was primarily driven by a $7.0 million payment made to the Stockholder Representatives in accordance with the TRA of which $1.4 million was in excess of the amount previously accrued and was recorded within other (income) expense in the statement of operations. See “Notes to the Financial Statements—17. Tax Receivable Agreement” for additional information. In addition, we made a charitable contribution of $1.0 million that is specifically creditable against current income tax in the State of Florida, as allowed under state law, and recorded within other expense in the statements of operations.

Income Taxes

In 2015, our effective tax rate was 36.9% compared to 36.1% in 2014 and 37.4% in 2013. While we expect our tax rate to be fairly consistent in the near term, it will tend to vary depending on recurring items such as the amount of income we earn in each state and the state tax rate applicable to such income. Discrete items particular to a given year may also affect our effective tax rates.

Quarterly Financial Data (unaudited)



	Three Months Ended
	March 31, 2014		June 30, 2014		September 30, 2014		December 31, 2014		March 31, 2015		June 30, 2015		September 30, 2015		December 31, 2015
	(in thousands, except share and per share amounts)
Total operating revenue	$	437,987	$	499,337	$	519,769	$	474,487	$	493,355	$	553,421	$	574,841	$	519,846
Passenger	253,878		302,487		317,038		271,569		273,466		308,573		319,812		267,487
Non-ticket	184,109		196,850		202,731		202,918		219,889		244,848		255,029		252,359
Operating income	59,953		105,144		100,191		89,975		109,251		122,315		157,219		120,337
Net income	$	37,706	$	64,849	$	67,000	$	55,909	$	69,002	$	76,704	$	97,114	$	74,400
Earnings Per Share: