Originally Posted by
Pontius Navigator
Actually, thinking a bit deeper, he may have something. Two transponders. One with the usual ATC 4-octal Mode A and another with a discrete aircraft ID. The latter would of course need larger and discrete number or maybe the route identified would suffice. It need not be displayed on ATC screens but never the less recorded in the data store.
The military use multi-mode transponders so the principle exists.
The transponder response does have the aircraft ident embedded in it, a techy even told us how it is transferred to a replacement box and what equip is used ( it can only be done if aircraft logic shows ground nor air.
However who on the ground can see or access that data in the return I don't know.