Easiest way to get triggering aircraft id?

[No.401_Wolverine]

What's the easiest way to get the id of an aircraft that has triggered a trigger (pass through for example)?

I have a nice little script working that detects aircraft and I think I know how to get it to put up more info about the aircraft, but I'm having trouble finding a simple way to get the triggering AiAirGroup's identity to use for mining the data.

Thanks for any help.