Make an exception for AI to where they cant lock and or fire if a plane has its gear down and below 50m. Simple solution, AI is too overpowering when flying over base and shooting at landed/landing aircraft.
Being shoot at even at the airport or while on the ground is part of the game. If you need help getting the vehicle of the ground, work with other players to help you. There are many AA vehicles on the map. There are around 6 fixed wing aircraft , multiple rotary wings vehicles, infantry that can carry AA and the defender at terminal. Saying the AI should not be able to shoot at aircraft when on the ground is like saying the AI should not be able to shoot at infantry while prone.
Most of the time while I am listening to the TS channel, the pilots work well together identifying the enemy aircraft and taking it down within a couple minutes.
This is all beside the main point that it would add considerable overheadto pervent the AI from shoot at specific units.