Several years ago I researched the subject of the tartans of the USAF & USAFR Pipe Bands; the article is posted on the STM's web site:

http://www.scottishtartans.org/USAF.htm

I was never able to establish that the tartan was officially adopted by the USAFR, but one can certainly argue that is the de facto tartan, as not only the band, but many current and former members of the USAF and USAFR wear it.

Regards,

Todd