The younger sibling of the army and navy, the air force was still in its infancy when World War II began. Britain was the first country in the world to establish an independent (of army or navy) air force in 1918, a number of European countries following soon after. Thus, World War II was a period of rapid expansion for air forces with new roles being introduced and others changing with improving technology.
Presented below are a selection of qualification/trade badges from air forces (or army air forces in the case of countries who had not yet established independent air forces) around the world.
Britain opted for a no-nonsense approach to identification with a clear initial for their aircrew (N – navigator, E – engineer, AG – air gunner, S – signaller) while most other countries opted for symbols with varying levels of flamboyance. You will notice that for the most part they were in agreement on which symbols best represented the different roles.