Category: How flying works
How Pilots Land a Plane in a Crosswind: Crabbing and Sideslips
Short answer
Pilots either point the nose into the wind so the aircraft tracks along the runway (crabbing) or lower the into-wind wing (a sideslip). Before touchdown, the nose must line up with the runway so the wheels do not land sideways.
Headwind and crosswind
Most landings are made with the wind at an angle to the runway. Pilots split the wind into a headwind along the runway and a crosswind at 90° to it. The crosswind equals the wind speed times the sine of the angle between wind and runway: half the wind at 30°, about 70 percent at 45° and about 87 percent at 60°. So a 20-knot wind (about 37 km/h) at 30° gives a 10-knot crosswind.
Try it yourself
Move the wind speed and wind angle sliders and watch how the headwind, the crosswind and the crab angle change.
The crab method
A flying aircraft moves with the air around it, so a crosswind carries it sideways. In the crab method, the pilot turns the nose into the wind so the aircraft's path stays over the runway centreline while it flies slightly sideways, like a crab. The stronger the crosswind compared with the airspeed, the larger this crab angle. Just before touchdown, the pilot uses the rudder (the tail control worked by the pedals) to line the nose up with the runway.
The wing-low (sideslip) method
In the wing-low method, the pilot uses the rudder to keep the nose lined up with the runway and lowers the into-wind wing with the ailerons (the wing controls that bank the aircraft), just enough to stop the drift. The aircraft then touches down first on the into-wind main wheel. The FAA handbook recommends this method in most cases. On a long approach, pilots may crab first and change to wing-low before the flare (the gentle nose-up just before touchdown).
Why it is harder, and the demonstrated crosswind
Touching down while drifting or crabbed puts strong side loads on the landing gear. As the aircraft slows, the controls work less well and need larger inputs, and on the ground the wind tries to turn the aircraft and lift the into-wind wing.
An aircraft's manual usually gives a demonstrated crosswind: the strongest crosswind tested satisfactorily in certification. FAA guidance for light aircraft treats it as performance information, not a limit, unless testing found it limiting. Pilots should still know it and avoid winds beyond what the aircraft can handle.
Common mistakes and myths
- Touching down while still crabbed or drifting, which side-loads the landing gear.
- Levelling the wings in the flare, which lets the drift start again.
- Easing off the into-wind aileron as the aircraft slows after touchdown. It needs more, not less.
Questions people ask
What is the difference between crabbing and a sideslip?
In a crab, the wings stay level and the nose points into the wind, so the aircraft flies slightly sideways. In a sideslip, one wing is lowered and the nose stays in line with the runway. Both keep the aircraft over the centreline.
How strong a crosswind can a plane land in?
It depends on the aircraft. Under the long-standing certification rule, a light aircraft must be controllable in a 90° crosswind of at least two-tenths of its stall speed in the landing configuration. If full rudder cannot stop a sideslip from turning the aircraft, the wind is too strong for that runway.
Can I practise a crosswind landing in AeroFox?
Yes, in a light trainer. In the lesson, a 12-knot wind blows from your left front, about 10 knots of it across the runway. AeroFox is a learning tool, not certified training, and does not count toward a licence.
Practise it in the simulator
The free Crosswind landing lesson lets you crab down the approach in a light trainer, change to a wing-low sideslip by about 200 ft (60 m) and touch down without drifting.
Related explainers
Sources
- Airplane Flying Handbook (FAA-H-8083-3C), chapter 9: approaches and landings (FAA)
- Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), chapters 11 and 16 (FAA)
- Advisory Circular 23-8C, Flight Test Guide for Certification of Part 23 Airplanes (FAA)
- Vector components (NASA Glenn Research Center)
About these explainers
AeroFox is a free, public-interest project with no paid features. The explainers are written by the AeroFox team from public sources such as FAA handbooks, NASA and regulators, and, for the lessons from the news, from the news reports we link to. Each page lists its sources, and pages are updated when the facts or the lessons change. They explain ideas. They are not flight instruction, medical advice or legal advice, and they do not count toward any licence.