Two cases:
General case of exploitation, helicopters shooting FAF missiles while hovering above their bases, then landing before counterfire reaches them. They can’t be hit unless a visually guided missile has LOS on them and the pilot screws up, and they’re inmune to SAMs who can’t hit them on the ground. This is badly designed and should end.
Exploitation case in a specific map: map Domination Sinai, enemy helicopter can hover above the cliffs on the northern spawn and shoot at the northern team from behind their spawn while staying out of reach for SPAAs in the northern team. Haven’t encountered this when playing southern team. The only (theoretical) countermeasure is northern team spawning an airplane and air-to-air killing the enemy helicopter… but usually at that stage any aircraft will have 10 SAMs up their tailpipe well before being in reach for tracking a helicopter right above the rocks. This is badly designed and should end.