By Simon Montague BBC Transport Correspondent

British Airways has launched an urgent investigation after part of a Concorde tail rudder fell off during a flight from London to New York, the BBC has learned.

It is the fifth rudder failure on a BA Concorde since 1989, despite changes to inspection procedures aimed at preventing such incidents.

We are happy there is no safety risk, and happy for Concorde operations to continue

Civil Aviation Authority

The Concorde pilots said they felt a continuous vibration as the aircraft decelerated from supersonic speed on its approach into New York last Wednesday.

After a normal landing they found that part of the lower rudder on the tail fin was missing.

None of the 96 passengers or nine crew on board were injured in the incident.

Inspections

David Learmount, of Flight International magazine, said BA could "cope with problems of this kind and the aircraft is completely controllable during such incidents".

However, air accident investigators are concerned that the incident is "very similar" to a previous one in 1998.

A report from the Air Accidents Investigation Branch (AAIB) said that improved, non-destructive and visual inspections should have detected that the metal skin and honeycomb core of the rudder were coming apart.

But the AAIB stressed that Concorde remains safe to fly, even if an aircraft loses one of the four wedges which make up the vertical tail rudder.

The Civil Aviation Authority, which regulates safety, says it has a continuing programme of monitoring Concorde rudders.

A spokesman said: "We are happy there is no safety risk, and happy for Concorde operations to continue".

'Not needed'

Pilots have found that partial loss of the rudder does not significantly affect aircraft handling.

BA Concorde rudder failures

27 November 2002: New York flight loses part of lower rudder 8 October 1998: Part of lower rudder detaches off Newfoundland 21 March 1992: Large section of upper rudder lost at twice speed of sound 4 January 1991: Portion of upper rudder separates during London - New York flight 12 April 1989: Part of upper rudder detaches at 44,000 feet

Jock Lowe, a pilot with 25 years of Concorde experience, told the BBC the plane can fly "very successfully" with just one rudder surface.

He said the affected panel "only comes into use for steering during take-off and if there is an engine failure or if there is a cross-wind, so for most flights it is not needed at all".

David Learmount said that a way of strengthening the rudders will be made a priority.

But he added: "Operationally, the loss had no effect on the plane.

"I understand the pilots felt a little 'pop' as they accelerated, but thought little of it as there was no apparent fault."

Visual inspections

The airline's fleet of seven Concordes was re-equipped with new rudders 10 years ago, following a series of problems.

But a further incident occurred in 1998, when part of a lower rudder detached, again on a London to New York flight.

In November it was revealed that two BA Concordes had developed other problems during transatlantic flights.

An engine failure forced one New York-bound plane to turn back to London and another flight was forced to cut its speed when cracks appeared in a window.

In another incident, engine failure forced an Air France Concorde to descend thousands of metres, reportedly causing panic on board.

November also marked the first anniversary of the return of Concorde passenger services, following the deaths of 113 people when one of the Air France planes crashed near Paris in July 2000.