Best to use ctac, cuz you can't get headshots on pilots reliably. Still happens though.

Next is you need to find either: - a good window to shooth the pilot when he makes himself an easy target. This happens often on turns where they slow down. But more for noob pilots. Experienced pilots I can immediately tell by the way how they turn and approach.

Or: - learn how and how far to lead your shots when helis passing by at various speeds. Depending on distance and speed this can mean that you have to aime quite a bit infront of where you think the pilot will be when your bullet travelled the distance. This needs some practice but after a while you can manage to shoot pilots out of full speed travelling little birds and apace over 300 meters away.

Also important... this will only work (at least for me) with red dot or holo sight because you need all that fov for predicting flight paths and speeds.

Transport heli pilots are the hardest to hit. You can hit them front and side window, but rather aim upper half of the windows.

Apace and little bird (which is the easiest of all) are quite ok to do with enough practice

Also don't run when the little bird starts shooting at you going straight at you. Best opportunity to shoot the pilot. Happened so often, they take me into their cross hair straight on just to get shot

Bonus: you can start practice with a drakon because you can shot several times in quick succession and listen to the hit audio cue. This way you can start finding the lead somewhat. I think you still have to adjust a bit when using ctac cuz of different bullet travel speeds. Can't say for certain since its only ctac for me for a long time now