Wind Shear and Turbulence
What the exam tests
This domain tests wind shear, its causes and turbulence recognition, including low-level and convective hazards.
Core rules
- Wind shear is a change in wind speed or direction over a short distance or time; it can occur vertically or horizontally.
- Low-level shear is critical on approach and departure; a sudden headwind loss causes airspeed and lift loss, while a gain causes excess airspeed.
- Causes include fronts, inversions, gust fronts, microbursts, mountain waves and surface friction.
- Turbulence types include mechanical (terrain/obstacles), thermal (convection), frontal and clear-air turbulence. Report significant encounters as pilot reports.
Worked example
On final, a crew experiences 20 kt headwind at 1,000 ft reducing to 5 kt at the surface. That is 15 kt of shear over 1,000 ft. If the aircraft descends through it, airspeed trends toward the lower value, so the crew should carry extra approach speed and be ready for a gust or go-around. The reasoning links shear magnitude to the direction of airspeed change.
Traps
Treating shear as only turbulence; ignoring microbursts because the surface wind looks light; assuming shear is only frontal; failing to report a significant encounter.