The story
According to the February 1, 1976 edition of the Official Airline Guide (OAG), Cochise was operating de Havilland Canada DHC-6 Twin Otter turboprop aircraft as well as Cessna 402 prop aircraft. By 1979, the airline was flying Swearingen Metroliner (Metro II) turboprops. In 1979, the airline purchased two Convair 440 which were previously operated by Scandinavian Airlines. One route served with the Metro II at this time was Tucson (TUS) - Phoenix (PHX) - Yuma (YUM) - Imperial, CA (IPL) - Los Angeles (LAX) while another route served Phoenix (PHX) - Flagstaff (FLG) - Winslow (INW) - Gallup (GUP).
Besides serving Phoenix, Tucson, Imperial and Yuma, the February 1, 1976 OAG listed scheduled service operated by Cochise into the following destinations in Arizona: Flagstaff (FLG), Grand Canyon National Park Airport (GCN), Kingman (IGM), Lake Havasu City (LHU), Page (PGA), Prescott (PRC) and Winslow (INW).
By 1981, Cochise was flying a Convair 440 propliner nonstop between Tucson (TUS) and San Diego (SAN) and also on the Tucson - Phoenix - Yuma - El Centro - Los Angeles route in addition to Metro II propjet service on the latter route. The Convair 440 was the largest aircraft type ever operated by the airline. Also in 1981, Cochise was flying a Phoenix (PHX) - Blythe, CA (BLH) - Los Angeles (LAX) route in addition to operating its other routes within Arizona and southern California.
The air carrier's two letter airline code in the OAG was "DP".
From Wikipedia’s article on Cochise Airlines, shared under CC BY-SA 4.0.3