[RobertHoudin]

An airfoil (wing) creates lift when air flows from the leading edge to the trailing edge, and the speed of this airflow is one of the factors which determine how much lift is generated. A strong tailwind will interrupt the airflow, induce turbulence and decrease lift. Thus, an airfoil moving into a headwind will generate greater lift than one moving through a tailwind.

[mistercow]

Ah, so it's just the transition to a tailwind that causes problems? That makes sense.