Headquartered at the now-closed Stapleton International Airport in Denver, Colorado, the airline ceased operations on August 24, 1986.

The original Frontier Airlines dates to November 27, 1946, when Monarch Air Lines began service in the Four Corners states of Colorado, Utah, New Mexico, and Arizona.

[3] Frontier continued to operate Douglas DC-3s and added Convair CV-340s beginning in 1959; the company introduced a new logo on the new aircraft.

In later years de Havilland Canada DHC-6 Twin Otters and Beech 99s were added to serve cities too small for the Convair 580.

Three years later, Maytag sold his stock in March 1962 to the Goldfield Corp., whereupon he bought a controlling interest in National Airlines.

[5][6] Lewis W. Dymond then became president of Frontier and, under his guidance, the airline entered the jet age with new Boeing 727-100s on September 30, 1966.

[8] Frontier would later introduce its own Orange County service as well as flights to a number of other destinations in California.

This same annual report states the airline transported over 80 percent of its passenger traffic on board its growing fleet of Boeing 737-200 jets in 1977.

By 1979, the airline had 5,100 employees and operated 35 Boeing 737-200 and 25 Convair 580 aircraft serving 94 cities in 26 states, Canada and Mexico.

Frontier Horizon ceased operations in April 1985[3] after it was acquired by a new start up air carrier, Skybus Airlines, that same year.

People Express Airlines acquired Frontier on October 5, 1985, and put Larry Martin in charge after Joe O'Gorman resigned on January 29, 1986.

Frontier's last timetable was dated September 3, 1986; the airline had halted operations and filed bankruptcy the week before.

Some bankruptcy proceedings ended on May 31, 1990, forty years after Frontier was formed, but the Chapter 11 case was closed July 22, 1998, by Charles E. Matheson, Chief Judge.

[citation needed] According to the July 1, 1968 Frontier Airlines system timetable, Aero Commander 500 twin engine prop aircraft were being operated via contract by Combs Aviation on behalf of Frontier on scheduled passenger flights serving smaller communities in Montana and Wyoming at this time.