The image of an ATR 72 crossing an overpass in knife-edge flight, its left wing tip grazing a taxicab, appeared on global media, prompting widespread speculation about the cause of the upset. Loss of control following a propulsion system malfunction was a plausible guess due to its frequency in accident causation.1
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And that is, indeed, what happened, according to the formal investigation conducted by the Aviation Safety Council of Taiwan (ASC). However, the instigating factor likely came as a surprise to most aviation safety specialists due to its rarity: The ASC found that the accident was prompted by a spurious activation of the propeller autofeather system.
Moreover, the council’s fina…
