From: Denver Colorado
I made a post that has some related information in your other thread about air missions.
At the start of your turn, turn OFF ground support.
Always set Recon Escort OFF.
There is only one way that I know of to ensure your fighters are available to escort specific human designated missions. That way is to be very regimented in how you use your air assets during the turn, because as soon as a fighter flies, it is ineligible to escort ground attack.
This micro-management is most easily accomplished (for me) by turning Ground Support ON/OFF frequently. Also, I perform specific ground attack missions prior to most anything else ("usually"). I also fly air transport early in the turn, to enable the highest number of escort missions (I might also fly air transport later in the turn and risk un-escorted missions). Where it really matters, I will fly air supply (not fuel) with level bombers.
You are correct that the Air Doctrine screen has no impact on 'priority' of escort duty.
When fighters are not available to escort, often it's for some reason you're not paying attention to (see the other response in the other thread) or (maddeningly) aware of.
I hope this is of some help.
Spring 2018-Playing: Demyansk Shield: Frozen Fortress; Advanced Squad Leader,
Rulebooks: ASL (always ASL), Holland'44, Demyansk Shield: Frozen Fortress