Wings of Mercy -- Film Description:
"Yet again in its history, aviation is used to save lives—in this instance, through Saskatchewan's air ambulance service. A desperate phone call for help from an outlying area—and within fifteen minutes a plane is on its way, guided to the patient by such landmarks as a coal bin, or a thin column of smoke on a northern lakeshore. Organized and operated by experienced flyers, the service provides speedy hospitalization and treatment to the ill and injured."
-- National Film Board of Canada

Source:
National Film Board of Canada. "NFB -- Wings of Mercy" National Film Board of Canada. http://www.onf-nfb.gc.ca/eng/collection/film/?id=17522.