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Glossary

Crab Angle

Learn what crab angle is, how pilots use it to correct for crosswind drift, and why it's critical for maintaining course during flight and landing.

Author: Daniel Mark · Founder & Editor, AviatopiaPublished: Reading time: 2 min read

Crab angle is the angle between an aircraft's nose and its actual path over the ground, used to compensate for crosswind during flight.

How It Works#

Wind rarely blows from directly ahead or behind. When wind pushes from the side, an aircraft flying straight ahead will drift off course. The pilot points the nose into the wind to cancel that drift and stay on track.

The angle between the nose direction and the desired track is the crab angle. A stronger crosswind requires a larger crab angle. A headwind component reduces the required correction.

Pilots calculate crab angle using the wind correction angle (WCA) formula. The simplified version is:

\text{WCA} \approx \arcsin\left\(\frac{V_W \sin\(\alpha\\)}{V_{TAS}}\right)

Here, VWV_W is wind speed, α\alpha is the angle between the wind direction and the desired track, and VTASV_{TAS} is true airspeed. In practice, most pilots use a flight computer or cockpit tools rather than solving this by hand.

Example in Aviation#

A pilot is flying a cross-country route. The desired track is 090° (due east). Wind is blowing from 045° at 20 knots. The aircraft's true airspeed is 120 knots.

To maintain the 090° track, the pilot points the nose slightly north of east, perhaps 008° to the left of the track. The aircraft crabs into the wind. The ground track stays 090° even though the nose points at roughly 082°.

Why It Matters#

Every pilot flying cross-country routes encounters crosswinds. Ignoring wind drift causes course deviations that compound over distance. A small uncorrected drift at the start of a long leg can put an aircraft miles off course by the end.

Crab angle also plays a critical role during landing. Pilots flying an ILS (Instrument Landing System) approach in crosswind conditions often crab into the wind on final. They must then straighten the aircraft before touchdown, or land with the gear aligned with the runway.

Key Takeaways#

  • Crab angle corrects for crosswind drift to keep the aircraft on its intended ground track.
  • A stronger crosswind or lower airspeed requires a larger crab angle.
  • The nose points into the wind, but the aircraft moves along the desired track.
  • During landing, pilots remove the crab before touchdown to protect the landing gear.
  • Crab angle and wind correction angle refer to the same practical concept.

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