In October 2013, Republic Airways Holdings entered into an agreement with private equity firm Indigo Partners to sell Frontier Airlines for approximately $145 million. According to Indigo, the transaction would further Frontier's evolution into an ultra-low-cost carrier. In December 2013, Indigo Partners LLC, through an affiliate, completed the purchase of Frontier Airlines from Republic Airways Holdings. The airline's headquarters will remain in Denver. Republic Airways Holdings subsidiary Republic Airlines no longer flies Embraer 190 aircraft on behalf of Frontier, as of January 1, 2014.
In 2008, jetBlue partnered with Irish flagship carrier Aer Lingus to allow passengers to switch between airlines on a single ticket for flights with connections in New York–JFK or Boston Logan. Unlike traditional codeshare agreements, the companies cannot sell seats on each other's flights, so customers initiate the purchase on one airline's website and then are transferred to the other site to complete the transaction.
As part of its plan to stay competitive in reaction to the entry of Southwest Airlines into Denver, the company underwent a reorganization early in 2006. On April 3, 2006, Frontier created Frontier Airlines Holdings (FRNT), a holding company incorporated in Delaware to take advantage of favorable tax laws in that state. The corporate headquarters did not leave Colorado.
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.
Allegiant Air has been closely monitored by the FAA due to many emergency landings and aborted takeoffs. ABC interviewed a former Allegiant mechanic, who said "Dedicated steps were not being performed with maintenance manuals or even with general practices, before an aircraft is released." Many of these incidents had involved Allegiant's aging MD-80 aircraft, which as of November 2018 have been replaced by newer Airbus A320 family aircraft. 46 of the 86 aircraft have made emergency landings, all of which were on MD-80s. The average age of Allegiant's MD-80 fleet was 29 years compared to less than 13 years for its Airbus fleet.
Like Ryanair, the low-cost airline founded by the Ryan family of Ireland, who also have invested in Allegiant, the airline seeks ancillary revenue to supplement ticket revenue. These ancillary fees include those for checking luggage, carrying on luggage (other than a small personal item), buying food and drinks on board, obtaining advance seat assignments, and more. Allegiant CEO Maurice Gallagher said in 2009, "We collect $110 from you at the end of your trip. If I tried to charge you $110 up front, you wouldn't pay it. But if I sell you a $75 ticket and you self-select the rest, you will."
The initial JetExpress partnership with Mesa ended in January 2004, when Horizon Air was selected to operate the routes. Horizon utilized slightly larger CRJ-700 regional jet aircraft on these routes. In August 2006, Frontier and Horizon ended their partnership. While Frontier was generally pleased with Horizon's operation, the carrier decided that it needed to revisit the agreement and find a provider with additional regional jets to grow the operation. The last of the CRJ-700's was returned to the Horizon Air fleet on November 30, 2007.