1)Increase the skill settings for bravery
2)Make sure the planes have a high fuel level when they go into combat
3)Discipline skill setting can also have an effect (high settings tend to stick together in groups)
4) keep opposing numbers ~even ( or even more opposition )
These things help- whether they will get it to a standard you desire is another matter
Vision/awareness sliders do also have some effect, not sure but height advantage might help.
It seems to be more an 'art' rather than a 'science' with multiple things affecting how dogfights turn out
In my experience CoD's AI have something like a 'pool' of bravery- determined by the bravery level. This is reduced by decreasing fuel level, the number of times it is 'threatened' by enemy AI etc, until a point at which 'they've had enough' and bug out at the first opportunity and remain in this state (I call it RTB Dummies) at which point they are pretty much 'target drones'- although they do some avoiding now if attacked- but quickly try to resume RTB.
One thing I often do is to give defending fighters a waypoint after contact at low level/high speed- so at least when they do 'bug out' they get out of the fight in a quicker/more realistic fashion.
That's my experience anyway, maybe others can explain it better?