BTW I never flew against Mig 21's, but a lot of F-5's which are slightly larger and easier to see. They were flown by very well trained Aggressor pilots. Their technique when approaching the merge was to "hit the dissappear switch" which simply means they pointed at you. I have seen Mig 21's up close and am amazed how tiny they are. Mig 15's and 17's as well.