Ever since the crash of American Eagle Flight 4184 (an ATR 72) in Roselawn, Ind., on Oct. 31, 1994, the NTSB has been recommending that the FAA enact a new rule that the Board believes might have prevented these accidents. As a result of the crash of Flight 4184, the NTSB recommended that the FAA “prohibit the use of the autopilot” during encounters with icing conditions. The idea behind this recommendation is that the autopilot could mask a change in flight control feel during icing conditions and that pilots might be better able to detect the effects of icing on flight controls if they were hand-flying rather than using the autopilot.
In accidents where the NTSB makes this recommendation and others, the airplane stalled and crashed after the autopilot suddenly switched off after exceeding pitch and/or bank limits, leaving the pilots in a situation where they had to take control of an airplane in an attitude from which it was difficult to recover. There are also some incidents where pilots lost control after icing encounters with the autopilot engaged.
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