In 1954, Émilien Pronovost purchased a bush aviation company, La Sarre Air Services, which was headquartered in Nord-du-Québec and operated in a territory that enjoyed a wealth of natural resources but few if any roads.

Successively supported by his daughters Lise and Claude, then his sons Jean and Louis, Pronovost played a key role in the development of Quebec's largest construction site at the time, the James Bay Project, a series of hydroelectric power stations on the La Grande River.

With a fleet of around 40 aircraft, Propair was the largest bush aviation company in Eastern Canada, serving nearly the entire Quebec region.

Once the region's major projects were completed, and with the signing of the James Bay and Northern Quebec Agreement and its impact on hunting and fishing trips, Propair found itself with a larger fleet than needed to meet the demands of its traditional market.

At 12 minutes after take-off, at 3,800 m (12,500 ft) above sea level, the crew radioed air traffic control (ATC) indicating a hydraulic problem and requested a return to Dorval.