I would guess those who are aviators and those attached to an aviation unit haven't used illegal drugs and that's a good thing. My experience was a little different with me being in the Army. These were your regular 11B & secondary MOS guys.

There were a few people in my unit (US Army) that smoked pot on a regular basis. The NCO who was in charge of our unit's drug testing would inform all his buddies as to when the test would be. Some would stop and drink plenty of water, vinegar and cranberry juice while others still swallowed Golden Seal tablets like chicklets!!!