Passengers flying Allegiant Air are encouraged to check their flight status before arriving at the airport as the airline has been forced to cancel dozens of flights while it awaits new aircraft.In a travel alert posted to its website, Allegiant revealed a pair of rescheduled flights and 16 canceled flights for Friday, six cancellations for June 21 and another 14 canceled flights for June 22.Affected destinations include Myrtle Beach, South Carolina; Las Vegas; Pittsburgh and St. Petersburg, Florida, among others.The airline is in the process of replacing its aging MD-80 aircraft with Airbus A320 planes."You may or may not be aware that we are in the process of transitioning to a single fleet type," Allegiant spokesperson Krysta Levy said in a statement. "Unfortunately, some of the delivery dates for aircraft scheduled to join our fleet have fallen short of the projections, leaving us with limited resources available and the very difficult choice to cancel certain flights."According to the airline, the new aircraft must still go through the induction process and are "being held up by a leasing company we’re transacting with.""We have offered options to our passengers on canceled flights, including recommendations to other flights or refunds. We sincerely apologize for the interruption to our passengers' travel plans," added Levy.The airline said it was experiencing an extremely high call volume Thursday.pic.twitter.com/yp1xcMFshN— Allegiant (@Allegiant) June 14, 2018According to flight-tracking website FlightAware.com, nearly one-quarter of Allegiant's scheduled flights for Thursday (103) were delayed and five percent (21) were canceled.The upcoming cancellations are the latest blow for the low-cost carrier, which was recently the subject of a troubling 60 Minutes report and fined by the U.S. Department of Transportation, which announced it's conducting an audit into the Federal Aviation Administration's oversight of maintenance issues at Allegiant last month.