THE pilots of a Singapore Airlines plane made basic errors during take-off at a New Zealand airport in March, causing the tail of the 747 to drag almost 500m along the runway, a damning safety investigation has found.

The wrong weight was used in calculating the speed and as a result, the captain took off at too slow a speed and the plane veered to the right, according to New Zealand's Transport Accident Investigation Commission (TAIC).

None of the 369 passengers, 17 cabin crew or three pilots was injured in the March 12 incident, but the tail was badly damaged and the aircraft was forced to turn back and make an emergency landing, reported wire agencies yesterday.

A spokesman for SIA, in response to Straits Times queries, said the airline has received a copy of the report and that the commission's safety recommendations had been, or were being, implemented fully.

'Singapore Airlines is sorry that pilot error prior to the take-off led to this aviation occurrence.

'That error caused the pilots to calculate a take-off speed that was too slow, hence the aircraft's tail struck the runway before the aircraft became airborne,' the spokesman said.

The report pointed out that the accident could have been worse if the plane had gone off the runway.

The incident has led to several changes in procedures.

Said the SIA spokesman: 'We wish to assure our customers that the lessons from this occurrence and arising out of this thorough investigation by the TAIC have been learnt and several procedural changes have already been implemented.'

She did not elaborate, but one change mentioned in the report is that SIA pilots now need to always check their manual calculations against those of the flight management computer.

However, the spokesman said that the safe return of the plane to Auckland shortly after take-off was a reflection of the pilots' training and good airmanship.

But all the pilots were reprimanded and the captain, who has since left the airline, was demoted.

The incident happened when the first officer mistakenly entered an aircraft weight that was 100 tonnes lighter than actual in the take-off speed calculations, said the report.

The captain failed to spot the error when he checked it, and the second officer, who was busy explaining an earlier delay to the airport's staff, did not check it.

All three pilots failed to notice the difference between their own calculation and that of the flight management computer.

As a result, the captain tried to take off at 221kmh rather than the correct 272kmh, said the report.

This slow take-off tilted the plane, causing its tail to hit the runway and drag for 490m while it struggled to get airborne.

The report said the captain had recently switched from flying Airbus planes, which usually have lower take-off speeds than Boeing 747s.

The first officer was appropriately qualified, but had little experience piloting 747-400s, while the third pilot was very experienced.

After landing, the plane's flight recorder had recorded a conversation between the pilots.

Referring to the take-off weight calculations, the captain said: 'Should be a three.'

The first officer replied: 'Take-off weight?'

The captain replied: 'yeah' and the first officer said '346'.

The third pilot commented 'gosh', before adding: 'I should have checked it.'

Last year, SIA dismissed two pilots of the SQ006 flight that crashed in Taiwan three years ago.