Macklemore knows... when you can't find a partner to get you into the Mile High Club, you just handle it on your own...

TMZ caught up to him as he was catching flight at LAX last night when and they asked if he'd ever got some on a plane ... which doesn't seem to be an easy task..

Macklemore admitted he'd never actually got some on a plane ... but revealed he has performed some actions on himself ... in the bathroom, of course. 

Imagine if the plane hit some turbulence...that would turn it up a notch!!