I have been playing Battle of Britain in multiplayer and my opponent encircled one of my 109's and reduced it to 1 strength point. On my turn when I tried to return it to a airfield to repair I could not move it

Is this a bug or has a ZoC for aircraft been but in place for Battle of Britain?
Also to destroy a airfield does it have to be clear of AAA units when you bomb it?
Thanks in advance for replies clearing up this foe me