Plain English Meaning

It is the gap between how hard the wind is blowing steadily and how hard it is gusting. Pilots add half of that gap to their landing approach speed so a sudden lull in the wind does not leave them too slow to fly safely.

Full Definition

The numerical difference between the steady wind speed and the peak gust speed reported in current wind conditions. On approach, pilots add half of this difference to their normal final approach speed to maintain controllability and adequate margin above stall when gusts are present.

Context Anchor

Seen in approach and landing discussions when deciding whether to add extra speed for .