November 2009 Issue

Improper IFR

That’s the coldly clinical term the NTSB uses to describe a host of IFR sins eventually leading to wrecks. Most occur on non-precision approaches.

Even the casual student of why aircraft accidents happen knows that in a large percentage of them, weather is a factor. (It’s about 15 percent.) That’s not to say weather caused the accident, just it was implicated as one link in the chain of events that led to the typical accident. When we think "weather," icing, thunderstorms, low visibility and turbulence come to mind, as well they should. But the NTSB’s accident files reveal a particular subset of accidents in which pilots operating in flyable if challenging IMC prang perfectly good airplanes into terrain and obstacles for no apparent reason. The agency throws these into a grab bag category it blandly calls "improper IFR." This catchall describes a narrow range of sins, but most of them relate to vertical rather than horizontal transgressions. We read enough accident reports to confess a certain discouragement at the level of skill—or lack thereof—of the typical pilot in the U.S. But there’s good news: The number of incidents of NTSB-reported improper IFR have declined markedly in recent years. The NTSB reported no accidents in this category between 2006 and 2009, but there were 47 between 1989 and 2005.

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