As of 0e78e51

Player A is landed at KSC outside of the safety bubble
Player B is landed at on the runway in an airplane.

After player B leaves the runway safety bubble, player A can see him take off and fly around, and continues to see as long as he is within 2.5km.

If player B goes beyond 2.5km, player A can still see the marker and distance, but if player B comes back within 2.5km, to player A, player B appears stuck at a 2.5km distance not updating even while player B is actually buzzing player A at <200m range. Player B has to land for player A to see the true position again.

If player B goes beyond around 10km (didn't get the exact distance) then he disappears for player A and doesn't respawn at all until landing.

This should have been fixed with HackyInAtmoLoad. Reopen this if it comes back.