Gust Envelope

081-06-03Pablo Asensio Martínez2026-04-011 min

Gust Effect

A vertical gust changes the effective Angle of Attack (AoA) of the wing.

  • Updraft: Increases AoA -> Increases Lift -> Increases Load Factor ($n > 1$).
  • Downdraft: Decreases AoA -> Decreases Lift -> Decreases Load Factor ($n < 1$).

Factors Affecting Gust Sensitivity

  1. Airspeed (V): Faster speed -> Greater change in Lift for the same gust -> Higher Gust Load.
  2. Wing Loading (W/S): Higher Wing Loading (heavier plane, smaller wing) -> Less sensitive to gusts -> Lower Gust Load. A heavy plane "rides" turbulence better.
  3. Lift Curve Slope: Straight wings (high slope) are more sensitive than swept wings (low slope).
  4. Altitude: Higher altitude -> Lower density -> Lower forces (for the same TAS, but gusts are usually defined in TAS or EAS). Gusts are generally stronger at low altitude.

Gust Envelope Diagram

Superimposed on the Manoeuvring Envelope.

  • Shows the g-load imposed by a standard gust (e.g., 66 fps, 50 fps, 25 fps) at speeds $V_B$, $V_C$, and $V_D$.
  • Vb (Design Speed for Max Gust Intensity): The speed to fly in severe turbulence.
Written and reviewed by

Pablo Asensio · 2026-04-01

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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