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Cirrus and Safety

Early speculation says that pilot error caused the Oct. 11 small-plane crash in New York City. New York Yankees pitcher Cory Lidle had his pilot’s license less than a year  before he and his co-pilot, a flight instructor named Tyler Stanger, fatally crashed Lidle’s 2002 Cirrus SR20 Aircraft into a high-rise condominium building on Manhattan’s East Side. Stanger, who was 26, was not local to the area (Lidle flew him out from California, where for three years Stanger had been giving flight instruction using Cessnas), and Stanger may have lacked experience with the Cirrus. According to the Washington Post, Cirrus Design’s records indicate Stanger never completed “a five-day training course that the company requires for those who teach students how to fly its airplanes.”

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According to the National Transportation Safety Board, since 2000 the Cirrus SR20 and its newer version, the SR22, have had 20 other fatal crashes resulting in 41 deaths, including those last month of Italian designer Ivan Luini and Sergio Savarese. We still don’t know what went wrong in this latest crash; the NTSB is still investigating the circumstances of the accident. But on Oct. 13 the journalist (and amateur pilot) James Fallows, who praised the Cirrus’ safety features in his book, Free Flight, emphasized in his Web log  the sheer difficulty of turning the plane around—as Lidle and Stanger were required to do, lest they fly into LaGuardia Airport’s air space—in a “box canyon”:

Making a 180-degree turn to get out of a “box canyon”—a literal one, in the mountains, or an airspace one, like the situation at the top of the East River—is harder than you might think. The best way to imagine an airplane’s performance is to think of a bicycle. Like a bicycle, an airplane has to keep moving in order to stay up. If a bike goes too slowly, it falls over. If an airplane goes too slowly, it falls out of the sky. For airplanes the phenomenon is called “stalling,” and it refers not to engine performance but to the fact that the air is not going over the wings quickly enough to provide lift for the plane. But as with a bike, the faster an airplane goes, the more space it needs to complete a U-turn. A bicyclist who is roaring down a hill toward a hairpin curve needs to calculate just how fast he can go to make the turn. Something similar happens with an airplane nearing a forced 180-degree turn, like the one on the East River. The pilot has to figure out the combination of air speed (slower the better, but not slow enough to risk a stall), bank angle (steeper the better — except that at a steeper angle the risk of stalling increases), use of flaps, allowable loss of altitude, and so on to create the so-called “minimum radius turn.”

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In light of this analysis, it’s instructive to learn (from the “Safety Features” section of the Cirrus Design Web site) that Cirrus touts the “stall prevention” features of its small airplanes. Whether Lidle and Stanger made poor use of these features, or whether these features somehow failed Lidle and Stanger, may never be known.

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