How does the “Kill-Count” work?

[TRC Subaru]

What I do not understand is that in Training, in XBOX, after you shoot the enemy plane and it crashes into the ground, it is counted as a “Kill”. But in MP it often does not, possibly because of how it calculates how much damage was inflected by each plane that shot at it, who shot at it last, etc. Apparently the PS3 users are saying the “Kill-Count-Issue” is still not as good as it should be. The way it is now I do not truly understand. Sometimes I damage a plane and it crashes and I get the kill, other times I believe I damage the plane even worse and it crashes in a shorter amount of time and I still don’t get the Kill. Sometimes I hit the plane just before it goes in and I get the kill, sometimes I don’t – I really can’t figure the “Kill-Count” programming, although slight lag and miss-count of damage may also be impacting the kill determination. Anyone have any ideas on exactly what the program is looking for to get a Kill?