Design fault caused take-off alert on 747

A British Airways jet was allowed to fly to Australia and back despite an incident seconds after taking off from Heathrow which caused the nose to pitch down unexpectedly.

An investigation by the Air Accident Investigation Branch (AAIB) showed it was caused by a design fault in the controls in the newest version of the Boeing 747. The AAIB has alerted US safety authorities, recommending a design change to a unit controlling power to the tail plane elevators which determine an aircraft's rate of climb.

The 747-400 aircraft was flying to Bangkok on the night of 7 October 1993, with 408 people aboard. It was 100ft off the ground when the nose, which was supposed to be pointing 14 degrees up, suddenly pitched down to 8 degrees up, far too low for an aircraft which had just taken off. The pilot prevented the aircraft from pointing down and managed to restore the proper rate of climb within five seconds.

The investigation showed that a design fault appears to allow the power control unit to be set wrongly.

The pilot blamed the problem on the controls or turbulence and continued to Bangkok. The aircraft later continued to Melbourne with a fresh crew. The fault was not found until flight recorder tapes were analysed and it was reported to the AAIB six days after the incident.