No probs with pressure! However other factors can have an influence - I also took my friend's daughter, who is the same age and also type 1. Both kids tested their BG before flying and were similar levels and had identical snacks - when they landed and came back to the hangar, they both tested again, and my son (who had enjoyed himself and been relaxed) had a stable BG, whereas my friend's daughter had felt very nervous in the air and ended up on 2.7mmol - yikes!
Funny you should say "a van with wings" - he flew in a Bulldog, and when the pilot started up the engine, I joked to the ex-RAF chap standing next to me what a "noisy old bus" it was....turned out that it was his own plane, and his pride and joy, oops! 😛. They took off from a grass runway, and then had to bank sharply to avoid entering Luton Airport airspace. After that the pilot let my son take the controls until it was time to land - you can imagine how thrilling it was for him. 😎