Originally Posted by
ShyTorque
It's normal for military units to ask; some other agencies also. I always give it when asked to pass my details anyway.
Normal when taking off or landing at a military airfield but not for an en-route service. Many civil airfields ask too so that, as others have said, in case of emergency the rescuers know how many to look for.
I know I've said this before, but many years ago when I still worked at Farnborough, we had a report of an 'R22' crashing near Twyford and the two occupants had died. I checked the reg, saw we had worked it into Wycombe and noted it was a Hughes 269 not an R22. Phoned Wycombe and asked how many on board when it departed; they said it had booked out with 3 pob, so I contacted the AAIB investigator who was en-route (couldn't reach the rescue units on scene) and advised him. After a lot of searching, they found the third body some distance from the crash site and concluded they had exited the aircraft before impact.
There was always the chance this third person might have survived and died of their injuries had they not searched for them.