Allegiant Air (G4, Las Vegas Harry Reid) is having to withdraw its planned operations to Fort Collins/Loveland, which were due to commence on November 21, and would have been its only scheduled services.

The US ultra-low-cost carrier (ULCC) which was intending to operate services from Phoenix Sky Harbor (2x weekly) and Las Vegas Harry Reid (4x weekly), has blamed the lack of an air control tower at Northern Colorado Regional Airport, which serves the communities of Fort Collins and Loveland, for the second time.

The airline's customers from the airport received an e-mail informing them of the problem a month prior to the launch of services.

"As part of our agreement to schedule service in Fort Collins, Allegiant was given assurances that an FAA-certified air traffic control tower would be in place at the airport this fall, well in advance of our first scheduled flights," Allegiant wrote to customers.

"Unfortunately, circumstances beyond our control have left that promise unfulfilled, much to our frustration. Because we cannot responsibly operate at the airport without a control tower in place, we are left with no choice but to cancel service at this time."

The US Federal Aviation Authority (FAA) has delayed the inspection of the airport's tower until January 2020. Upon receiving that news, the airport and city officials had devised an alternate solution - a mobile tower - which would have bridged the gap between the start of services in November and the FAA inspection in January.

"The FAA couldn't certify it, and it's not clear why," said Fort Collins Mayor Wade Troxell.