Back in 1999 I flew into a few RAF bases in a Seneca. I asked wht they had PAPI's at 2.5deg.
I was told that it was in case a Tornado had a failure which meant that it would have its wing swung all the way back.
Seemed a reasonable explanation at the time.
It would also hold good for flapless landings.
Last edited by renard; 26th August 2008 at 18:44.
Reason: to add a bit more info