Plane & Pilot
Wednesday, June 1, 2005

Control The Crosswind!


It can be vexing to any pilot, but is there a right and wrong way to take on the wind?


There are several ways to start an argument. They range from the old favorites, politics and religion, to the blonde/redhead/brunette thing. Or you can simply state that there’s only one right way to land an airplane in a crosswind and that’s the way you do it. Stand back, folks, brutal words to follow.
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One of the few POHs with a wind chart in it showed that this particular airplane’s limit with the wind 20 degrees off the nose was 60 mph! When it was 40 degrees, the wind limit was 30 mph, and when it was 90 degrees to the runway, the airplane was rated at 20 mph demonstrated crosswind. If those numbers seem high, think of it this way: They’ve proven this airplane will handle 20 mph right across the runway. So, when it’s at 20 degrees, it takes 60 mph to generate a side component of 20 mph.

When the wind is coming at us from an angle, the airplane and the pilot combination become even more critical because every airplane has the aforementioned limit. At some point, even at full aileron and full rudder, it can’t maintain a straight line. It should be noted, though, that the crosswind limitation of most airplanes is much higher than the crosswind limitation of most pilots.

We’ve said that the amount of wind and its direction is paramount to deciding whether or not we’re actually going flying. Then we have to toss in gusts, which easily can have more effect than everything discussed to this point. It’s the gusts that make any wind difficult. Even a really high crosswind is no sweat if it’s steady, while a much smaller wind with hard gusts can be a bear. Suffice it to say that as the gust spread starts to become a sizable proportion of an airplane’s stalling speed, it’s time to sit up and take notice.

The reason we don’t all destroy airplanes in every gusty crosswind landing is because the strength of the wind goes down as you get closer to the runway. In theory, the wind is zero right on the surface (in the boundary layer), then builds up to the level reported at about 15 feet off the ground. In nearly all winds, the most critical time is as you’re working your way down into ground effect because, once in ground effect and closing on the runway, the wind gradient attenuates and life gets a little less hectic. There are exceptions to that rule, however. Again, see the sidebar for these exceptions.

Gusts also are the determining factor as to the speed and flap issue. As for the flaps, some POHs will tell you what to do in a given situation. A lot of old heads, however, say the higher the gust spread, the less flaps should be used. In a steady wind, the flaps just act like flaps, although as the wind gets really crossed, excess flaps often begin to act as additional side area, so more rudder is required to keep it straight. Flaps, however, accentuate the effects of gusts, making balloons higher and the attendant speed bleed off at the top of a balloon more severe.





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