British Airways flight called mayday on approach to Heathrow

A British Airways flight issued a "mayday" distress call on its approach to Heathrow Airport earlier this month, according to a statement from France's accident investigation authority.

The call was made on an Airbus A320 flying from Dusseldorf airport in Germany on 6 July following two stall warnings on the aircraft, before it landed without further incident.

The UK's Air Accidents Investigation Branch (AAIB) said it was "investigating a serious incident".

A British Airways spokesperson said the airline was assisting the AAIB with its investigation and was not legally able to comment further at this stage.

The French Air Safety Investigation Authority, the BEA, said that as the plane approached Heathrow, there was a data system failure which triggered a stall warning.

The crew then flew the aircraft in a different mode called "alternate law", which removes some automated flight protection systems. Another stall warning then occurred at 3,000 feet - which experts say was likely to have been just miles away from the airport.

The urgency call the crew had already made was upgraded to mayday, indicating imminent danger.

The BEA website attributed the statement to the AAIB, but the AAIB would not confirm it was from them.

They issued the following statement: "The AAIB is investigating a serious incident involving a commercial aircraft which occurred on 6 July on approach to Heathrow airport."

It said the investigation would be a correspondence investigation, meaning that no team would be sent to carry out field investigations.

Aviation safety investigator David Gleave said there are different forms of mayday calls, and to send an urgency message was "not unusual".

"You could have sick passengers on board who need urgent medical attention… so it's up to the captains' discretion as to what they call, but its very unusual for it to be a significant failure on board the aeroplane."