Air vehicles are way too weak

Why do helicopters die in one hit? Did nobody playtest this once? The enemy team can have as many engineers as they want. Each engineer gets 5 no skill lock on brain dead 1 shot kill weapons. It basically takes two of them concentrating their shared braincell looking at the sky every couple minutes to one shot a helicopter. Glad I get one countermeasure every 30 seconds or whatever while they can dump 10 locking rockets on me in 10 seconds.