I don't know if this has been posted yet, but how about awarding partial kills to people that hit an aircraft according to the amount of damage they do(and possibly whether they hit vital parts of the aircraft or not). It would solve awkward situations like this: Somebody else hits a guy's engine. Later on you rip the same person to pieces. You will only get an assist,even though there is the possiblity that the enemy could have landed at his base safely, even if the engine was hit.
How about both pilots getting 1/2 kill? variations of the ratio can account for more/less damage done by one person.