As aircraft have become more reliable, the proportion of crashes caused by pilot error has increased and now stands at around 50%. Aircraft are complex machines that require a lot of management. Because pilots actively engage with the aircraft at every stage of a flight, there are numerous opportunities for this to go wrong, from failing to programme the vital flight-management computer (FMC) correctly to miscalculating the required fuel uplift.
Equipment failures still account for around 20% of aircraft losses, despite improvements in design and manufacturing quality. While engines are significantly more reliable today than they were half a century ago, they still occasionally suffer catastrophic failures. Sometimes, new technologies introduce new types of failure. In the 1950s, for example, the introduction of high-flying, pressurised jet aircraft introduced an entirely new hazard – metal fatigue brought on by the hull’s pressurisation cycle. Several high-profile disasters caused by this problem led to the withdrawal of the de Havilland Comet aircraft model, pending design changes.
Bad weather accounts for around 10% of aircraft losses. Despite a plethora of electronic aids like gyroscopic compasses, satellite navigation and weather data uplinks, aircraft still founder in storms, snow and fog. One of the most notorious bad-weather incidents occurred in February 1958 when a British European Airways twin-engined passenger aircraft crashed while attempting to take off from Munich-Riem Airport. Many of the 23 killed on the aircraft played for Manchester United Football Club. Investigators established that the aircraft had been slowed to such a degree by slush, that it failed to achieve take-off speed.
About 10% of aircraft losses are caused by sabotage. As with lightning strikes, the risk posed by sabotage is much less than many people seem to believe. Nevertheless, there have been numerous spectacular and shocking attacks by saboteurs. The September 1970 hijacking of three passenger jet aircraft to Dawsons Field in Jordan was a watershed moment in aviation history that prompted a review of security.Despite improvements, malcontents still penetrate the security veil, as with the 2001 “shoe-bomber”, Richard Reid. Fortunately, Reid’s attempt to bring down an aircraft mid-flight proved unsuccessful.
5. Other Forms Of Human Error
The remaining losses are attributed to other types of human error, like mistakes made by air traffic controllers, dispatchers, loaders, fuellers or maintenance engineers. In 1990, a windscreen blowout on a British Airways flight nearly cost the life of the aircraft’s captain. According to the Air Accidents Investigation Branch, almost all of the windscreen’s 90 securing bolts were of smaller than specified diameter. Maintenance engineer was blamed responsible for fitting the new windscreen oversized countersinks.