Overpitched - does an aeroplane wing stall at a specific groundspeed? No but it does at a specific airspeed. If an aircraft flys past you (you are on the ground not moving) at an indicated 60 kts airspeed into a 20 kts head wind, it will fly past you at 40 kts GS. If it turns round and flys past with a 20 kt tailwind (still with 60 kts IAS) it will fly past you at 80 kts GS. As far as you are concerned the plane has twice the speed and therefore momentum because you are stationary on the ground. As far as the pilot of the plane is concerned he is flying at 60 kts airspeed both ways and the plane behaves in exactly the same manner (same power setting, attitude etc). His reference is airspeed (which is moving) and yours is a fixed point on the ground, which is not.