Her parents had both worked as fighter-control operators for the Royal Canadian Air Force (RCAF).
Mosher chose to pursue a military career, and was accepted into officer training for the Air Force, graduating in 1976.
Mosher began undertaking private flying lessons as preparation should the Air Force begin to accept female pilots.
[2] With fellow Captains Nora Bottomley and Dee Brasseur, they were accepted to undergo flight training in the Air Force, and were presented with their wings on February 13, 1981.
She was subsequently posted as staff officer to the director of recruiting services at the National Defense Headquarters.