In summer 2015, a rash of midair breakdowns drew federal scrutiny. "Before the night was finished on June 25, 2015, five Allegiant flights had been interrupted in four hours, all because different planes had failed in midair," reported the Tampa Bay Times. Since October 2015, the Federal Aviation Administration has kept Allegiant under close supervision. In July 2015, Allegiant Air announced bases would be established at the Asheville Regional Airport and Cincinnati/Northern Kentucky International Airport, becoming the first base at a non-vacation destination.
In February 2015, Frontier announced that they will begin service to several destinations from Atlanta adding the airport as a focus city. In July, Frontier also began decreasing service from Washington Dulles International Airport removing the airport as a focus city. In early 2016 Frontier announced major route expansion from airports nationwide including Atlanta, Chicago, Cincinnati, Cleveland, Orlando, and Philadelphia. In June 2016, Frontier re-established service to Port Columbus International Airport. In May 2017, the airline announced opening a new crew base in Las Vegas in the fall 2017 to improve operational reliability and potentially create new jobs in Las Vegas. In December 2017, Frontier began service to Buffalo, New York, with service to Denver, Colorado, and Florida, including Miami, Fort Myers, Orlando, and Tampa.
Allegiant already flies into many major airports, including McCarran International (Las Vegas) and Fort Lauderdale-Hollywood International Airport. In June 2013, Allegiant deviated from this strategy with plans to compete with Southwest Airlines by offering direct flights between Las Vegas and Austin, a medium hub served by 10 carriers with non-stop routes to over 40 destinations. The airline also flies less frequently compared to the major airlines, operating routes two or three times per week. That requires fewer crews and allows less time-pressured aircraft maintenance.
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.