The British Commonwealth Air Training Plan
With the outbreak of hostilities in 1939, one of Canada's major responsibilities was to provide air training facilities removed from the theatre of war. On December 17, 1939, the Plan was inaugurated. The first schools were opened the following year, among them No. 12 Elementary Flying Training School here at Sky Harbour. At the height of operations there were 38 training units in Ontario alone, including 32 air training schools. Before termination of the Plan on March 31, 1945, these and 70 similar establishments elsewhere in Canada trained over 300,000 aircrew, ground crew and airwomen, mostly from Canada, Britain, Australia and New Zealand but including American volunteers and escapees from Nazi-occupied Europe.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.