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.
Plain English
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.
Context Anchor
Seen in approach and landing discussions when deciding whether to add extra speed for gusty wind conditions.
Derivation
Gust' comes from the Old Norse 'gustr' meaning a sudden rush of wind. 'Factor' comes from the Latin 'facere,' meaning to make or do — in this sense, a number that contributes to a calculation. Together, the term names the gust component you factor into your approach speed.
Why Pilots Care
A higher gust factor tells the pilot to add half the difference to the target approach speed, helping maintain a safe margin above stall speed when the wind suddenly drops or shifts.
Analogy
Like the difference between a steady breeze and the stronger puffs that occasionally shove you harder than the average wind.
Intuition Check
The gust factor is not the full gust speed. It is only the extra amount above the steady wind speed.
Example Sentence 1
With winds reported at 15 gusting to 25, the pilot calculated a gust factor of 10 and added 5 knots to the normal approach speed.
Example Sentence 2
With a gust factor of 6 knots the instructor recommended carrying an extra 3 knots to keep the approach stabilized through the gusts.