By Guess and By God -- Film Description:
"An entertaining, tongue-in-cheek account of the pioneers of Canada's airmail services, and the difficulties they had flying planes that had just recently come off the drawing-board."
-- National Film Board of Canada

Source:
National Film Board of Canada. "NFB -- By Guess and By God" National Film Board of Canada. http://onf-nfb.gc.ca/en/our-collection/?idfilm=11087.