There are likely no truly uncontacted tribes left. There are some that choose to remain as they are, but they’ve been contacted at some point, and now know enough to know that anything strange they see is caused by us. Some maintain regular contact by way of tribe members travelling to cities and learning whatever they learn. So a lot of them probably know about airplanes.

These days most of them are more akin to mennonites and Amish, with one huge exception being the tribe out in the Maldives somewhere (the one that attacks on sight).