In October 2013, jetBlue introduced Mint, a premium cabin service on transcontinental and select Caribbean flights. The service began in 2014, using the Airbus A321-231 aircraft ordered by jetBlue. These planes are outfitted with winglets, as well as with "lie flat" seats, and moveable partitions that can create small suites on the airplane. Called "Mint" by jetBlue, these planes are configured with 16 business-class seats and 143 economy seats, instead of an all-economy configuration of 190 seats.
In March 2010, Allegiant purchased six used Boeing 757-200 jetliners as part of plans to begin flights to Hawaii, with deliveries from early 2010 to the fourth quarter of 2011. It gained the approval for type with the FAA in July 2011, and then worked with the FAA to obtain the appropriate ETOPS rating in order to be able to serve Hawaii. Allegiant no longer operates nonstop service to Honolulu from Las Vegas.
Dave Siegel took the chief executive officer role in January 2012. Siegel's tenure ran through May 2015, when he left for personal reasons and was succeeded by the company's chairman, Bill Franke, who would manage strategy and finances. In April 2014, Barry L. Biffle was appointed as the company's president, reporting to Siegel; after Siegel's departure, Biffle was charged with managing the company's day-to-day operations.
In 2014, Frontier announced it would be transitioning into an ultra-low cost carrier. Frontier will also cut several flights and jobs at their Denver hub and transition them to different markets. On January 16, 2015 Frontier announced that it will close both its Denver and Milwaukee call centers, laying off 1,300 employees and outsourcing the jobs to call center company, Sitel, which operates a large call center for Frontier in Las Cruces, New Mexico. As part of its transition to an ultra-low-cost airline, Frontier Airlines joined Spirit and Allegiant in June 2015 in removing its toll-free telephone number for customer service.
On August 4, 2008, the Associated Press reported that jetBlue would replace their recycled pillows and blankets with an "eco-friendly" pillow and blanket package that passengers would have to purchase for use. Each package will cost $7 and will include a $5 coupon from retailer Bed, Bath and Beyond. This decision is the latest in a series of moves designed to increase revenue. jetBlue told the Associated Press that it expects to collect $40 million from passengers selecting seats with extra legroom and $20 million from passengers paying $15 to check a second bag. As of September 8, 2008 JetBlue charges passengers $10–30 for an extended-leg-room seat depending on the length of the flight.
March 27, 2012: Flight 191 en route from New York City, to Las Vegas performed an emergency landing at Rick Husband Amarillo International Airport after the captain, Clayton Osbon, was locked out of the cockpit and subdued by passengers after he started acting erratically and ranting about terrorist. It is believed that Osbon suffered from an unspecified mental breakdown, and was treated by Northwest Texas Healthcare System. There were no fatalities.
A November 2016 analysis by the Tampa Bay Times noted that Allegiant's planes were four times more likely to have in-flight failures than other major US airlines. A 60 Minutes report by CBS News in 2018 continued to investigate the issues first raised by the Tampa Bay Times. Public records cited in the investigation found that the airline had more than 100 serious mechanical incidents between January 1, 2016 and October 31, 2017, including "mid-air engine failures, smoke and fumes in the cabin, rapid descents, flight control malfunctions, hydraulic leaks and aborted takeoffs." Other public records further revealed that Allegiant aircraft, on average, were nearly three and a half times more likely to have mid-air breakdowns than American, United, Delta, JetBlue and Spirit.
Allegiant also transports firefighters for the United States Forest Service as well as college basketball teams. Allegiant had a contract to supply charter flights from Miami to four cities in Cuba beginning June 2009. One aircraft was committed to the contract. The contract was for fixed-fee flying, meaning all the airline was required to do was provide the dry aircraft and the flight crew. The contractor was responsible for all other costs including fuel. However, Allegiant ended this service in August 2009.
In January 2008, Allegiant opened its sixth base at Washington's Bellingham International Airport. The airline bases two McDonnell Douglas MD-80 aircraft in Bellingham as part of the expansion. Routes served exclusively from Bellingham include Las Vegas, Palm Springs, San Diego, San Francisco and Phoenix. Expansion in Bellingham has been largely driven by its proximity to Greater Vancouver, British Columbia.
In May 2015, Indigo and Frontier announced the departure of David Siegel as CEO. He had already previously turned over the role of president to Barry Biffle, formerly of Spirit Airlines. Siegel was not immediately replaced. Instead, his duties were split between Biffle and Indigo chairman Bill Franke. Biffle cited operational issues in connection with Siegel's departure.
The company had charter contracts with Caesars Entertainment to ferry customers to Caesars casino properties through Reno-Tahoe International Airport, Laughlin/Bullhead International Airport and Tunica Municipal Airport. These contracts ended in December 2012 when Caesars Entertainment signed a new contract with Republic Airways to provide the charter service to Caesars properties in Atlantic City, New Jersey, Tunica, Mississippi and Laughlin, Nevada.
In May 2017, Allegiant Air took delivery of its first brand-new A320. Allegiant took delivery of ten new A320s in 2017 and is scheduled to accept two in 2018. All new aircraft will be painted in Allegiant's new livery at the time it is delivered. Older Airbus aircraft will be repainted during their C-checks. The new Airbus aircraft will have fuel-efficient sharklets. The new A320s seat 186 passengers, an increase of the 177 seats that are found in the rest of the Allegiant A320 fleet. To fit the additional nine seats, Allegiant opted for the Airbus Space-Flex V2 Lavatory. 
On April 10, 2008, Frontier filed for Chapter 11 bankruptcy in reaction to the intent of its credit card processor, First Data, to withhold significant proceeds from ticket sales.[better source needed] First Data decided that it would withhold 100% of the carrier's proceeds from ticket sales beginning May 1. According to Frontier's press release, "This change in practice would have represented a material change to our cash forecasts and business plan. Unchecked, it would have put severe restraints on Frontier's liquidity..." Its operation continued uninterrupted, though, as Chapter 11 bankruptcy protected the corporation's assets and allowed restructuring to ensure long-term viability. After months of losses, Frontier Airlines reported that they made their first profit during the month of November 2008, reporting US$2.9 million in net income for the month.