Plain English Meaning

A gentle wind coming from behind you and slightly off to one side. It is the worst wind for wake turbulence because it can push the swirling air left behind by another aircraft onto your runway and keep it there.

Full Definition

A wind of low velocity blowing from behind the aircraft at an angle, rather than directly down the runway. In wake turbulence avoidance, it is the most hazardous wind condition during takeoff or landing because it can move the upwind wingtip vortex of a preceding aircraft laterally onto the runway and hold the downwind vortex over the runway surface, exposing a following aircraft to .