Seeing someone hit from 2-1k is not unusual, it is usually because lag.
I have witnessed both ways these.
Been diving 500mph on climbing plane, he has seen me, waited till last moment, but in that time when he thinks I am 1.3k away and begins evansive, I am really about 300-450 yards his back and already perhaps shot him to death.
It doesn't have to be more lag than just a 600ms total lag, that makes already 1000 yards differences if shooter is alot faster and perhaps accerlating still.
(With total lag I mean lag between two players, with total of 600ms lag, it would be ie. other player has 200ms pings, other has 400ms ping times, total is then 600ms between them two, this is not unusual)
As long as I recall,theres always been these distance problems caused by lag. (includes warbirds, dawn of aces and so on..)
Just remember, you NEVER see your enemy there where he (enemy in his FE) is, due to lag.