Flying Seasons

Slipping, Crabbing, and Bouncing

April 1, 2007

You must be attempting a crosswind landing

The most difficult task in learning to fly is learning to land. From the point of view of an instructor, it is also the hardest to teach. The CFI has to find the right words and descriptions for each student, both on the ground during the pre- and postflight briefings and during the flight itself.

One thing that pilots quickly learn is that every landing, every approach, every flare is different. Even on the same runway, on the same day, in the same airplane with the same winds, every single landing is like a fingerprint; no two are ever the same. It's part of the challenge and part of the fun.

But in the beginning, landing is a hard skill to learn, because the pilot is dealing with an awful lot of moving parts, and is doing so in a 3-D environment. Thirty-five to 50 miles an hour may not sound like much in a car, but in a small airplane that is airborne, there are a lot of information and a lot of visual cues to process.

Eventually, most students — certainly those who eventually attain their private certificates — "break the code," and one day the pieces all come together and the student and the CFI both know that a major hurdle has been cleared. But if learning to land is the hardest skill to learn, then mastering crosswind landings is probably a close second.

When the winds are blowing right down the runway, things are much easier. There are no corrections to make and, when the wind is blowing, it helps you out because it slows everything down. However, crosswinds are different, because you need to be able to keep the axis of the airplane aligned with the centerline of the runway, and you need to be able to do so without allowing the airplane to drift. If the airplane is not aligned with the runway, or if you are drifting, you risk subjecting the landing gear to high loads. Drifting toward the downwind side of the runway also increases the risks of leaving the runway unexpectedly.

Interesting reading

A crosswind can be defined as any wind that is not in direct alignment with the runway, and it doesn't have to be much of a wind to cause trouble. A brief search of the AOPA Air Safety Foundation accident database yields an endless stream of accidents that occurred during the landing phase. This is no surprise, since landings are among the riskiest phases of flight. Crosswinds just add some flavor, not to mention some interesting reading.

Consider an accident that took place in Michigan on July 13, 2006, involving a student pilot in a Cessna 172. The lesson started off with the CFI flying five approaches and landings with the student to Runway 27L, after which the CFI exited the airplane (the accident report does not specify whether this was the student's first solo). At that point, the tower had the student begin using Runway 27R. On his first attempt, the student "could not get the airplane on centerline" and had to abandon the approach. On the second attempt, the descent was "fine" and the airspeed was "good" on final. The airplane was in a crab for the crosswind, and during the flare, the student added some left aileron into the wind and "the nose yawed to the left when he reduced power." He made matters worse by adding left rudder. When the airplane touched down, it left the runway and flipped over. The pilot was not injured.

The observed winds at 9:53 a.m. local time were 170 degrees at 7 knots. At the time of the accident, 11:06 a.m., they were variable at 4 knots.

If you think this is an aberration, consider an accident on August 13, 2002, involving a Quad City Challenger, a homebuilt ultralight that can be flown with or without floats. When approaching a lake in Massachusetts for landing, "a light gust of wind lifted the left wing." The aircraft was approximately a foot above the water when the gust occurred; the result was the right float contacting the water, causing the airplane to flip over and sink. Fortunately, the pilot was not injured.

Technique is key

When it comes to crosswind landings, it is all about technique. There are two methods of executing the landing. Both require that you fly the final approach with a crab into the wind to maintain centerline alignment. In the first method, you maintain the crab into the flare, and at the last moment, you use the rudder to kick the airplane straight. The hope here is that you are aligned with the centerline and minimize drift. It requires perfect timing, and does not leave much margin for error.

The second method is to slip the airplane as you flare. As you flare, you add aileron into the wind (left aileron for a left crosswind, right aileron for a right crosswind), and use the rudder to maintain runway alignment (see "License to Learn: Stop Stalling, Start Landing," page 46). You want to carry a few knots of extra speed to maintain full control authority. Done right, this results in a landing on one of the main wheels, and a sharp pilot can keep it on one wheel for a few seconds until the airplane settles on the other main and the nose.

Doing your crosswind landings this way takes more finesse and control, but it is a more controlled landing, and it greatly reduces the risk of drifting off the runway. It also reduces the sideload on the landing gear.

A common mistake with all landings, but especially with crosswind landings, is for the pilot to stop flying the airplane just because it is on the ground. On crosswind landings especially, it is critical that you continue to make control inputs and stay situationally aware of what is going on. Once the airplane is on the ground, you need to properly position the ailerons and elevator for ground operation, and braking should be done slowly and evenly until the airplane has slowed to taxi speed. It is easy to forget that rudder continues to act as a weathervane, and if the wind is blowing at any appreciable speed, the wings will produce lift.

The bounce

A search of the accident database reveals another common problem area in crosswind landings, and instructors everywhere will probably chuckle when they see this. Pilots performing crosswind landings tend to bounce. A lot. Whether it is from a lack of confidence or from a lack of practice, or both, the struggle to get the airplane on the ground often leads to a bounce, and the accident record is filled with pilots who find themselves back in the air struggling with what to do next. Too often, they are in a sort of no man's land, unable to maintain control enough to fly the airplane back to the ground, or unable to execute a successful go-around because of the drag from the flaps. This is exacerbated by the confusion that such a scenario can generate.

There are a couple of strategies here that can help. First of all, for any landing, but especially for a challenging one, you should have in your mind a touchdown target. If you can't be safely on the ground by your target, it's time to go around. This is especially true if you are landing in a direct crosswind, which eliminates the aerodynamic braking you get from a headwind during the roll. Second, if you bounce, you need to immediately assess whether you can make the landing on the runway or whether you should go around (a go-around is almost always the safest choice). If you do decide to go around, you need to immediately add full power and decrease your pitch. Flap configuration should be adjusted in accordance with the pilot's operating handbook. The worst thing you can do is to not act. Indecision is often the lead-in to accidents that end with "the aircraft veered off the runway.

An example is the pilot who landed a 172 in Key West, Florida, and bounced after experiencing a gust. The bounce carried him a few feet in the air, and when he came back to the ground, the airplane immediately departed the runway to the left. Key West International Airport is an example of an airport that pilots need to be aware of. It is a single-runway airport that is frequently subject to crosswinds, and since the airport is surrounded by water, those winds can be substantial, and gusty. Although airports are supposed to be built to favor the prevailing winds, that isn't always possible.

Speaking of substantial winds, most airplanes will have a published maximum demonstrated crosswind component. How limiting is that number? That depends. With experience and practice you might be able to exceed that in your flying, but bear in mind that if an accident occurs, you'll have some explaining to do. The maximum demonstrated crosswind component is the limit of what the test pilots were able to demonstrate, not necessarily the maximum that the airplane can handle. If you choose to exceed that value, do so cautiously.

Not just for GA

Crosswind landings are not just a challenge in general aviation aircraft, either. In December 2003, a FedEx crew was held responsible for destroying a DC-10 freighter on a landing in Oakland, California. The first officer was cited for a "failure to properly apply crosswind landing techniques to align the airplane with the runway centerline and to properly arrest the airplane's descent rate (flare) before the airplane touched down." The NTSB also said the captain failed "to adequately monitor the first officer's performance...or [to] initiate corrective action."

As a result of the hard landing, the right gear collapsed and a fire broke out, which destroyed the airframe. The landing took place on Runway 36R, and the reported winds were 320 degrees at 21 knots, a 40-degree crosswind in visual meteorological conditions. Conditions like this are everyday fare for an airline crew, which reinforces the need to treat crosswinds with respect and use proper technique. Complacency also may have been a factor.

The worst part of this for the captain is that he was less than a year from retirement.

Single-engine, multiengine, ultralight, or airliner, crosswind landings pose unique challenges. The best way to get comfortable with them is to practice them at every opportunity. Learn to execute the slip as you touch down, and do so consistently, and you will soon find that you actually look forward to crosswind landings.

Chip Wright, of Hebron, Kentucky, is a Canadair Regional Jet captain.