In 1975, an attempt to allow the use of both languages degenerated into a national strike and legal action. A coalition called the Association des gens de l’air gradually rallied public opinion. A commission of inquiry was finally charged with reviewing the matter and established that French could be used without posing a risk to flight safety. The government finally implemented its recommendations in 1980.
Association des gens de l’air du Québec v Lang,  2 F.C. 22 (F.C.T.D., affirmed  2 F.C. 371 (F.C.A.)