I've made a couple of 'parachute mobile' jumps (decades ago). 2M HT, "Hop-n-pop" from 7000'.The first one I did, too many hams in the SF Bay Area knew it was going to happen and the frequency was so loaded that only a few completed contacts were made. 2nd one, out in the Delta area, was more successful.
A couple of us skydiver / ham types were developing a plan to try a record-setting HT-to-HT QSO by getting canopies open at 15000' at opposite ends of the CA Central Valley. I don't remember why the plan finally fell apart but it never did happen, at least with my participation.
Being in the saddle at 10,000' or more makes you feel incredibly small and vulnerable, in case anyone wants to know.