Travelers flying out of Denver International Airport are getting new options for popular routes, just as flyers out of northern Colorado are seeing their options diminish.

Spirit Airlines Inc. on Tuesday announced it will add nonstop flights between Denver International Airport and Phoenix-Mesa Gateway Airport starting Oct. 4.

Spirit (Nasdaq: SAVE) is a self-described “ultra low”-cost airline based in Miramar,Florida. Spirit began flying out of DIA in May and offers flights to four destinations, DIA aviation manager Kim Day said in a press release from Spirit.

Meanwhile, Fort Collins-Loveland Municipal Airport will lose Allegiant Air flights to Las Vegas and Phoenix.

A spokeswoman for Allegiant Air confirmed Tuesday the airline plans to halt service.

According to a report in the Loveland Reporter-Herald, executives of Allegiant Air on Monday told representatives of the airport and the cities of Fort Collins and Loveland they will cease service in mid-October.

Allegiant Air offers flights to Las Vegas McCarran International and Phoenix-Mesa Gateway airports from Fort Collins-Loveland. The airline is a low-cost airline offering flights to airports serving small cities.

Allegiant Air is a subsidiary of Allegiant Travel Co. (Nasdaq: ALGT), which is based in Las Vegas.