In 2013, Allegiant acquired nine Airbus A320-200 aircraft from Spanish flag carrier Iberia. Seven of the A320s were delivered in 2013 and were used for growth into new markets, including destinations in Mexico and the Rocky Mountains, as well as airfields such as Charlottesville and Shenandoah Valley in Virginia and Trenton, New Jersey. On February 24, 2015, Allegiant announced the purchase of 2 additional A320s from Philippine Airlines which entered into service in 2015. Later in 2015, the airline announced a firm order for an Airbus A320 direct from Airbus, the first time it has purchased new aircraft from the supplier.
In August 2017, Allegiant announced a new base would be established at the Indianapolis International Airport. The base began operations in early 2018. In February 2018, Allegiant also announced a new base would be established at the Destin–Fort Walton Beach Airport. In June 2018, Allegiant added another base at McGhee Tyson Airport in Knoxville, Tennessee. In January 2019, Allegiant announced they would be adding another base at Gerald R. Ford International Airport in Grand Rapids, Michigan.
In the March edition of Airways Magazine, it was announced that once jetBlue partnered with Yahoo! and with BlackBerry producer Research in Motion, that the airline would offer free, limited Wi-Fi capabilities on a single aircraft, N651JB, an Airbus A320-232 dubbed "BetaBlue". People access e-mail with a Wi-Fi capable Blackberry, or use Yahoo!'s e-mail and instant messaging with a Wi-Fi capable laptop, while in flight over the US. LiveTV in Melbourne Florida, created and operated the "BetaBlue" prototype. The "BetaBlue" system utilized the bandwidth and infrastructure of defunct Airfone.
On July 1, 2010 Allegiant returned to Long Beach Airport (LGB) in Long Beach, California having previously served LGB with DC-9 jets with nonstop flights to Las Vegas (LAS) and Lake Tahoe (TVL) in 2000. The airline also intended to fly from Bellingham International Airport and Stockton several times a week; however, there is no service at present flown between these two cities although Allegiant continues to serve Stockton with flights to Las Vegas, Phoenix/Mesa and San Diego. In November 2011, Allegiant closed its Long Beach facility and consolidated all Los Angeles area flights at Los Angeles International (LAX).
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.
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In March 2011, Allegiant took over charter service to Wendover Airport for Peppermill Casinos, Inc. to shuttle customers to Peppermill's three casinos in West Wendover, Nevada; the Montego Bay Resort, the Rainbow Wendover and the Peppermill Wendover. Allegiant based one 150-seat, MD-80 series jet aircraft in Wendover and more than 20 employees, including maintenance, flight crews and stations personnel.