John,
YES, have seen many - posted a few photos a few weeks ago of planes coming and going - being behind, above and nose-to-nose...
Just flew into DULLES INTL Airport and had a screen full of targets! This was very helpful in that situation!
Mike Marra, N714AJ
In the above photo, you can see a plane flying just below my intended flight path to DULLES Airport...he is GREEN meaning if I am going south, then I see the RIGHT side of his aircraft (starboard) as he is flying to the west...helpful. BTW, I did not see him visually!
And there is one going the OTHER way!