[onepointsixC]

Because low flying aircraft are harder to detect than high flying aircraft. More over when their rcs has been significantly reduced. It’s not “invulnerable” no more than any stealth aircraft, submarine, tank, or any other platform is. It’s significantly harder to defeat.

[sofixa]

> Because low flying aircraft are harder to detect than high flying aircraft

From afar. But an attack helicopter will by definition be near the battlefield/enemy, so they'll have plenty of opportunities to see it and react.