i was talkin to my grandpa (ex ww2 halifax/ lancaster flight enginner in rcaf). he told me that there was not enough canadians to form there own squadrons and bomer groups. so what they did was they went in to the RAF untill later in the war when the canadians got enough men to form there own group.
In the first month of World War II there was only fifteen squadrons that could be brought up to strength and mobilized - twelve for home defence and three for overseas service. For aircraft there were 20 different types totaling 230 aircraft, over half were training or transport aircraft, and only nineteen 19 Hurricanes and and 10 Fairey Battle light bombers could be considered front line aircraft.
On the first of January 1944 the RCAF reached its peak wartime strength of 215,200 all ranks (including 15,153) women, 104,000 were in the British Commonwealth Air Training Plan, 64,928 were serving at home and 46,272 were serving overseas. There were 78 squadrons in service: 35 overseas, 43 at home (of which six had been ordered overseas).
Canadian officials proposed that a RCAF fighter and bomber group should be formed, however it was determined that due to the geographical nature of the RAF's fighter groups an all Canadian fighter group would require between 40 and 50 fighter squadrons and this was determined to be unfeasible. In the end only a Canadian bomber group was formed this being No. 6 (RCAF) Group.