Originally Posted by
bchandler02
You won't get any cell service at 10k. It actually cuts out way lower than that. Airplane mode is acceptable however.
Not true. I've left my cell on before and have received calls at 35k feet. Not great signal mind you, but it can come through.
It won't cause pilot to takeoff on wrong runway, but can cause issues during takeoff. The FA isn't going to know if you turned it off or not since they'll be buckled up. Thus they insist you do it before taxi. ]