US learns from NZ Boeing mishap

The New Zealand investigation of a near-disastrous Singapore Airlines Boeing 747 tail-strike at Auckland two years ago has prompted an international move to change on-board technology.

The United States National Transportation Safety Board (NTSB) has recommended the change to prevent what it describes as future similar dangerous miscalculations going unchallenged.

The Transport Accident Investigation Commission's chief commissioner and chairman of the International Transport Safety Association, Bill Jeffries, said the US move demonstrated the commission's contribution to safety.

Opening the International Surface Friction Conference in Christchurch yesterday, Mr Jeffries said the NTSB recognised the importance of commission investigator Ken Mathews' findings, particularly the significance of the recommendation to Boeing to modify the software in its aircraft flight management systems.

"The NTSB added its weight by recommending to the United States Federal Aviation Administration that it require the equipment manufacturer to modify its aircraft flight management system software, which would result in a global fix to a technology shortcoming that was found during the investigation," Mr Jeffries said.

On March 12, 2003, Singapore-bound flight SQ286, a Boeing 747-412, started its take-off at Auckland Airport. On board were 369 passengers, 17 cabin crew and three pilots.

When the captain lifted the nose - or "rotated" the aircraft - for take-off, the tail struck the runway and scraped for 490m until the plane became airborne.

The commission found the tail-strike happened because the rotation speed was 33 knots less than the 163 knots required for the Boeing's weight.

The rotation speed had been mistakenly calculated for an aircraft weighing 100 tonnes less than the actual weight of the plane.

A take-off weight transcription error, which remained undetected, led to the miscalculation of the take-off data, which in turn resulted in a low thrust setting and excessively slow speeds.

The system defences did not ensure the errors were detected.

In the take-off the plane moved close to the runway edge and the pilots did not respond correctly to a stall warning.

Had the plane moved off the runway or stalled there could have been a more serious accident.

- NZPA