A suggestion for solving flares

Nah, that's terrible idea. When the aircraft deploys heat traps a little too late, the missile explodes near it without directly hitting it, but it still makes some damage. This is how it should be. The problem with aircraft in Battlefield is that 90% of players can't use it properly, but the small number of good pilots can use it in a way that you can describe as legal cheating. Making jets of helicopters immune will only make things worse. Right now, you can have a good chance to take down even a sweatiest pilot a few times during the round. Make aircraft immune during flare drop, and we'll have these disgusting little birds and jets with 80-0 K/D all over again. No, thanks.

My memory isn't great, but I'm pretty sure this is how BF4 worked.  When you flared, it broke locks and kept you from locking that aircraft for a duration.  This sounds like your proposed solution to me.

In BF6 you spend more time locking a flare on the other side of the map from a teammate rather than the helo that is currently gunning you down.  Pretty bad design.