Wind shear

Wind shear is a change in wind speed, wind direction, or both over a short distance or time. It can occur horizontally or vertically. A rapid change in the wind vector can alter an aircraft's airspeed, groundspeed, flight path, and required control inputs, especially during takeoff, approach, and landing.

How it works

An aircraft's performance depends partly on the airflow around it. A sudden increase in headwind can temporarily increase indicated airspeed and lift. A sudden loss of headwind or increase in tailwind can reduce the energy available to maintain the flight path. Vertical movement and downdrafts can add further effects.

Wind shear may be associated with thunderstorms, fronts, terrain, temperature inversions, strong surface winds, and microbursts. The presence or absence of a reported shear alert does not prove that the air is free of shear.

Example

An aircraft on final approach encounters a rapid decrease in headwind below the glide path. Its indicated airspeed and lift can change while the runway remains ahead. The pilot follows the aircraft's approved wind shear warning and escape guidance rather than trying to infer a response from a general definition.

Why it matters

Wind shear can develop when surface weather appears manageable. Pilots review current warnings, PIREPs, airport alerts, radar information, and thunderstorm activity, then apply the aircraft and operator procedures. A forecast value is not a guarantee about the wind at a specific altitude.

Use official weather products and the aircraft's POH or AFM. The NOAA Aviation Weather Center and FAA Aeronautical Information Manual provide further reference material.

Related terms and tools

• Headwind component
• Tailwind component
• METAR