GIGO Almost Caused Plane to Crash


On the 20th of March, a United Arab Emirates Airbus A340-500 aircraft taking off from Melbourne, Australia struck its tail on the runway three times and a grassy area twice before being able to ascend. The aircraft sustained substantial damage as well as damaged some airport lighting and the airport's instrument landing system. The aircraft immediately returned to the airport for an emergency landing which it did without incident (although the landing was described as "hard").

As described by the Australian Transport Safety Bureau preliminary safety report released this week:

"At 2231:53, the captain called for the first officer to rotate. The first officer attempted to rotate the aircraft, but it did not respond immediately with a nose-up pitch. The captain again called 'rotate' and the first officer applied a greater nose-up command. The nose of the aircraft was raised and the tail made contact with the runway surface, but the aircraft did not begin to climb. The captain then selected TOGA on the thrust levers, the engines responded immediately, and the aircraft commenced a climb."

"The crew notified air traffic control of the tail strike and that they would be returning to Melbourne. While reviewing the aircraft's performance documentation in preparation for landing, the crew noticed that a take-off weight, which was 100 tonnes below the actual take-off weight of the aircraft, had inadvertently been used when completing the take-off performance calculation. The result of that incorrect take-off weight was to produce a thrust setting and take-off reference speeds that were lower than those required for the actual aircraft weight."

Apparently, "a crew member entered an incorrect figure into the electronic flight bag, a laptop computer which provides data to the aircraft's electronic flight control system." Instead of entering the true weight of 362 tonnes on the laptop, the aircraft weight actually entered was 262 tonnes.

The two aircraft pilots resigned/were fired from the airline. The airline also says that it has "added an extra step â'' and an additional computer â'' to its performance calculations to ensure they were executed properly."

An almost fatal case of computer garbage-in, garbage-out.


Risk Factor

IEEE Spectrum's risk analysis blog, featuring daily news, updates and analysis on computing and IT projects, software and systems failures, successes and innovations, security threats, and more.

Robert Charette
Spotsylvania, Va.
Willie D. Jones
New York City