Safety Publications/Articles

Way Too Windy

Learn your limitations

Wind catches a few students and many certificated pilots. On some days the outcome is questionable-there may be too much wind for us or for the aircraft. On other days the outcome is not in doubt-there will be a problem. A wind-related problem usually occurs during landing, but not always.

A Cessna 172 encountered a 35- to 45-knot gust of wind while taxiing. The airplane received substantial damage when it was blown over onto its back. The pilot reported that he got a weather briefing from flight service and thought that the weather "was OK," so he decided to fly. While taxiing south for Runway 32, he "?was using controls to help keep plane on the ground." After crossing Runway 7/25 the pilot said that a gust of wind "got under my tail and flipped the plane up on its nose, then over onto its back."

At 2:50 p.m. local time, the weather observation facility reported the winds to be from 270 degrees at 32 knots, gusting to 39 knots. Peak gusts were reported at 45 knots. You could write this mishap off as purely stupid, and in retrospect, the pilot involved would probably agree.

But if we are going to preserve aircraft and keep insurance rates down, it would be instructive to dig just a bit deeper. Some aircraft tolerate wind better than others. High-wing airplanes are said to be somewhat more susceptible to wind while on the ground but that has not been statistically proven. Cessnas are built in the Great Plains, where high winds are common and test pilots routinely fly in them-but probably not in conditions quite like this. These pilots are also very experienced.

A low-wing aircraft might have fared better, but there are no guarantees. Tailwheel aircraft are at much higher risk since they sit at a positive angle of attack on the ground and most are very light-especially Piper Cubs, Luscombes, and Taylorcrafts.

Aircraft are most vulnerable when taxiing downwind, but no matter which direction the aircraft is taxiing with respect to the wind, flight controls must be positioned to reduce the wind effects. With a quartering tailwind, such as the pilot involved in the accident experienced, the elevator should be down and the ailerons turned away from the wind-think, "Dive away from the wind." It is unclear whether this pilot employed the proper technique.

As a general rule, stay on the ground when the gusts exceed 65 percent of the flaps-up stall speed. There are a few aircraft/pilot combinations that could safely exceed that number, but for many of us, 40 percent-for example, a 20-knot gust in an airplane with a flaps-up stall speed of 50 knots-may be pushing it. Runway alignment, width, and length-as well as the surface type and condition-are all factors to consider. If you think that you can handle it, work up to the big wind gradually and have some recent experience. Instructors should discuss wind guidelines not only with students but also with anyone receiving a flight review.

The pilot wrote on his accident report form under the "How could this accident have been prevented?" section, "Keep plane tied up when it is too windy." Sounds like a good idea.

Bruce Landsberg is executive director of the AOPA Air Safety Foundation.

By Bruce Landsberg

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