Thursday, July 1, 2004
Crosswind Landings FAQs
Maintain and expand your skills by unraveling some frequently asked questions about this intricate technique
Q: Why is it so important to land astride the center stripes with no drift, the nose pointed straight ahead and at the right touchdown speed?
A: A centerline touchdown conserves runway width that may be needed in the event of an unanticipated swerve. Also, runways are often laid with a high crest for quick drainage. Any off-center touchdown on the sloping side surface invites a swerve.
Unless the plane’s nose is pointed straight ahead with no side drift, an unwanted side load is imposed against the landing gear. Then, chirping bird-hops or a hairy skid toward mishap, a tattered wingtip or even a possible overturn, is a real prospect.
An incorrect touchdown speed leads to a bounced landing that adds complication. If you bounce, maintain the crosswind correction so you’ll glide straight ahead, rather than bounce sideways into a side-load condition.
Q: Which crosswind technique works best: the crab, the slip or a combination of both?
A: The crab method establishes a wind-correction angle (or crab) on final and maintains a drift-free descent in this maneuver, until the moment of touchdown. At the exact instant before the tires touch, the plane is whipped into runway alignment and lands without a side drift, with the nose pointed straight down the runway.
Wind, however, is fickle. A gust in that moment when the plane is straightened out for touchdown will drift the plane to impose a side load on the gear. If you can’t predict the instant of touchdown and straighten out too early or too late, the plane will drift into a side load on impact. In the event of a bounced landing, there’s little time to reestablish the crab, and the drifting plane will re-land with a side load. So, unless the pilot is very skilled, the crab method can be risky.
The pilot using the slip method establishes the slip well out on final and corrects for the wind with that slip right on through touchdown. It’s a relatively easy and effective technique, but it’s uncomfortable and a little scary for non-pilot passengers—particularly if the direction of the slip leans them against the door. Also, due to the static port’s position, many airspeed indicators are inaccurate during a slip. Additionally, the POHs of some aircraft advise against prolonged slipping.
The combination crab-and-slip method is safe, easy to perform and more effective. To use this technique, establish an initial crab angle of about one degree for each one knot of crosswind component. (Expect to modify your crab angle throughout the letdown. Wind velocity and direction will change as you descend closer and closer to the ground.) By using the runway’s center stripes as references, you can prevent wind drift with a crab until you begin to round out.
As you round out, shift from the crab to a slip by lowering a wing into the wind and using the opposite rudder to hold the plane’s nose pointed straight down the center stripes. This slip is continued right through touchdown. Small changes in the magnitude of the slip easily allow for any momentary wind shift. It’s unnecessary to know exactly when the tires are going to touch; simply hold the touchdown attitude until they do. And if a bounce occurs, the ailerons are already doing their job to ensure that the airplane floats straight ahead. Most pilots prefer to use the combination crab-and-slip method for crosswind correction because of these reasons.
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Labels: Flight Hazards, Flying Skills, Learning Center, Safety, Takeoffs and Landings, Weather Skills