Ground effect

The condition of slightly increased air pressure below an airplane wing or helicopter rotor system that increases the amount of lift produced. It exists within approximately one wing span or one rotor diameter from the ground. It results from a reduction in upwash, downwash, and wingtip vortices, and provides a corresponding decrease in induced drag.

Source: Pilot's Handbook of Aeronautical Knowledge (definition from the FAA-H-8083-25B, 2016; current: FAA-H-8083-25C, 2023, with the October 2025 addendum).

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Glossary last updated 2026-10-28.

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