AA is once again useless against Jets.

In the old Battlefields, you had airfields where these jets spawned. They should bring this back, and not just magically spawn a jet in the match. These airfields should also be used for repair and/or rearm helicopters and jets and not magically repair and rearm in the air. They should also remove spawning in helicopters. Let them fly back and pick up a new group of players. 

Also, even if you hit a jet with a stinger it can just fly away and repair itself.

So in summary to kill a jet it either has to ignore it's magic flares, or you:

• Lock on and shoot at it then it flares.
• Then while you reload it turns overhead instead of leaving.
• Then you lock on and shoot it again and hit it.
• Then you shoot at it again and it flares again and it keeps turning over head instead of leaving.
• Then you get to finally shoot it a fourth time and hit it (maybe) and kill it.

I have one-shot two airplanes with my stinger near the beginning of a match. I suppose it's possible they took some chip damage prior, but I didn't see a lower health bar after hitting them a single time [after they popped their flairs]

You probably got the kill from them crashing or they got hit at the same time with another player.

Jets are the weakest they have ever been, especially in terms of hp and defense mechanism. The flares probably have the lowest active duration in any battlefield game and piloting a jet has probably never been this challenging (good thing imo).