Here is the history of the RCAF tartan and likely why they wear it?
The story of the Royal Canadian Air Force (RCAF) tartan goes back to January 1942.
Group Captain Elmer G. Fullerton, station commander of No. 9 Service Flying Training School, RCAF Station Summerside, Prince Edward Island, wanted to celebrate his Scottish heritage by organizing a “Robbie Burns Night” mess dinner. He borrowed bagpipes for his station band and searched for a suitable tartan to outfit the band in full Scottish regalia.
Group Captain Fullerton decided to design an original pattern that represented the Air Force. With coloured pencils in hand, he produced the prototype using light blue, dark blue and maroon colours. The original sample of the proposed RCAF tartan was created by Patricia Jenkins and Loom crofters of Gagetown, New Brunswick, with the Gagetown weavers also adding a white line in the design.
He then ordered a sample of the material to be sent to RCAF Headquarters in Ottawa for approval. The design was endorsed by the Air Council, and Air Vice-Marshal J. A. Sully sent it off to Scotland’s Lord Lyon, King of Arms, for approval in July 1942.
The approval was granted on August 15 and the design was officially registered as the RCAF tartan. Thus the RCAF became the first air force in the world to have its own distinctive tartan. The speed of the process from original concept to final approval in a period of eight months is truly awe-inspiring.
Since then, the distinctive RCAF tartan has been worn by members of RCAF pipe and drum bands. It is also used in other ways, including ties, mess kit cummerbunds, or ladies’ sashes
Being the junior service and a fairly new service in terms of the CAF I suppose they needed to created some traditions? I doubt they were or are stealing from the army as I'm pretty sure that kilts are not just "army" apparel. Like it or not our military is heavily influenced by other countries' traditions given our multicultural heritage.