FAA Private Pilot Helicopter (PRH)Performance and LimitationsMedium
Performance charts for hover and takeoff data are developed using smooth, steady wind conditions during flight testing. When actual wind conditions are gusty and variable, a pilot should:
- AUse the chart values exactly as published since wind gusts have no aerodynamic effect
- BApply an additional safety margin because gusty winds can cause unpredictable performance losses
- CIgnore wind entirely and use only the no-wind performance figures
- DAdd the full gust factor directly to the maximum gross weight shown on the chart
Show answer & explanationAnswer & explanation
Correct answer: B. Apply an additional safety margin because gusty winds can cause unpredictable performance losses
Published performance figures assume smooth, steady wind. Gusty or variable winds can momentarily disrupt airflow over the rotor and reduce effective translational lift, so pilots should add a safety margin rather than relying on chart values exactly as tested.
Why the other options are wrong
- A. Gusty winds do have real, unpredictable aerodynamic effects not captured by steady-wind test data.
- C. Wind still affects performance even in gusty conditions; it cannot simply be disregarded.
- D. There is no standard 'gust factor' added directly to gross weight limits on rotorcraft performance charts.
Gusty Wind & Performance Charts
Helicopter performance charts are based on steady wind test data; gusty or variable winds require pilots to add a safety margin because performance can be less predictable.
- Charts assume smooth, steady reported wind speed
- Gusts can cause sudden loss of translational lift or effective airspeed
- Pilots should build in extra performance margin in gusty conditions
Memory trick: Steady wind on paper, gusty wind in reality—always keep a buffer