A short-haul flight was at cruising altitude over England when two compasses split and the autopilot engaged. It was the sort of technical flap that air crews are trained to deal with. A quick check on the passenger cabin uncovered the reason for the problem. One of the passengers was using a lap top computer and all systems were returned to normal when it was switched off.
This seemingly routine act by a businessman on board the flight is one of the worrying hazards that air crews now have to contend with. And computers are not the only problem. CD players, personal stereo units and a video Walkman have all caused interference with flight controls in 19 incidents over the past five years.
They were detailed in a Commons written answer by Glenda Jackson, Under- Secretary of State for Transport, to Labour MP Gwyneth Dunwoody who described the results as "very worrying". Mrs Dunwoody said she was looking at links between air accidents and electronic gadgets.
The report shows that two flights in one month, March, 1993, suffered interference with their Omega navigation equipment from passengers' electronic gadgets.
Many passengers regard the routine warning about electronic equipment as a bore, and are tempted to use their mobile telephones, but the litany of possible disasters may make them think twice in future.
On 21 April 1994, a Boeing 767 suddenly found interference on all VHF channels. It was caused by a passenger's CD player. On 26 October 1995, a Boeing 737 suffered a sudden change to selected altitude on the autopilot flight direction system. No culprit was identified but interference from passengers' personal stereos was suspected.
On 19 March 1996, another 737 suffered a failure of the flight management system for several minutes. Interference from a portable computer was suspected.
On 21 July 1996, a Boeing 767 suffered the failure of the flight management system. Interference from a passenger's electronic equipment was suspected but no one was caught using any gadgets.
In the most recent case revealed by the Ministry of Transport, a short- haul flight was forced off its track on 9 January 1997. A passenger's computer is believed to have interfered with the navigation equipment.
But it is not always the fault of passengers. On 1 May 1995, significant interference was encountered with the flight deck instruments of an Augusta A109 helicopter. Experts concluded that it was probably caused by a high- intensity radio mast in the area.
The number of confidential reports involving human factors putting planes at risk is also rising. In 1995, there were 16 cases reported by air traffic controllers, but Ms Jackson said the number rose to 24 in 1996 and 39 in 1997.Reuse content