In the past 10 years, the National Transportation Safety Board has used the phrase “inadequate preflight inspection” in the probable causes of 15 fatal accidents. The most common direct cause is fuel contamination, usually with water, which typically leads to power loss after takeoff and a subsequent stall-spin. Other oversights include improperly latched baggage doors; various kinds of protective gear left in place, like pitot covers, control locks and foam air-intake plugs; oil filler or fuel tank caps unsecured; or failure to remove a boarding ladder or a chock. (A chock may seem unlikely to cause a fatal accident, but a passenger disembarked and was struck by an idling propeller while removing one from in front of a nosewheel.) Noteworthy about these causes is the fact that most of them-most especially unlatched baggage doors-should not have prevented the airplane from landing safely; but some pilots, rattled by the unfamiliar, lose control of perfectly flyable airplanes while returning to land.
Also noteworthy among the discrepancies listed here is the fact that any reasonably attentive preflight inspection would have detected them. The only instance, among the 15 accidents, of an anomaly that a normal preflight would not have detected was in the case of a long-stored airplane whose fuel tank vents had been clogged up by mud-daubing wasps; but that particular airplane had so many other things wrong with it, including a missing spark plug, that if the wasps hadn’t gotten it something else would.
