How do you destroy helicopters and jets as infantry?

No matter what I do, the missile just doesn't hit the target. Either because I die before it can lock on, or the missile just doesn't hit the target because of the flares. It also doesn't help that I feel like I'm the only one trying to shoot down a helicopter that's completely wrecking our team.

I dont know if its just skill issue or the AA weapons are just useless.