"I don't have a lot of time to think but it sounds like a reasonable plan from both of our perspectives, on the first few seconds of thought."
"I want to see green and purple lights flashing in the left field before I turn into it. This will not rule out interception attacks on this conversation, but it will slightly reassure me about whether I have causally interacted with Air Traffic Control at all during this conversation."
(There are, obviously, all sorts of encryption protocols that a plane and air traffic control would be using, if the plane's Network connection was functioning. This conversation is occurring along a channel that is meant to just-work-robustly-instead-of-going-through-complicated-computer-chips.)