If civilian airliners were used for PI; how close to the airliners would a fighter get?
Rules have obviously changed
trap one, in my time civilian aircraft were a prohibited intercept.
Not saying it was never done, BA Xmas flights for orphans getting intercepted is one type we used to get asked to intercept (Merry Xmas kids and see the F4 on our port wing!); Air Anglia used to get offended if they
weren't intercepted. And if QRA was loitering with Saxa with Bear F's playing north of the ADR, then they'd "intercept with caution", the transatlantic traffic for practice and to fill the hours.
But all prohibited by the book.
The one time the sh*t hit the fan was when Q1 jocularily claimed a Korean Airlines 747 on his report after one such Q trip. The reports going not only to HQSTC but also SACEUR. Unfortunately it was only a few months after the Russians had shot down a Korean Airlines 747.
Several days of sitting making transcripts of radio tapes, radar tracings and report writing later it didn't seem so funny to anyone else involved........