British Airways B772 enroute on Mar 6th 2015, cockpit temperature control and air flow problem

Last Update: August 14, 2015 / 20:38:23 GMT/Zulu time

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Incident Facts

Date of incident
Mar 6, 2015

Classification
Incident

Airline
British Airways

Flight number
BA-49

Departure
London Heathrow, United Kingdom

Destination
Seattle, United States

Aircraft Registration
G-RAES

Aircraft Type
Boeing 777-200

ICAO Type Designator
B772

A British Airways Boeing 777-200, registration G-RAES performing flight BA-49 from London Heathrow,EN (UK) to Seattle,WA (USA), was enroute at FL340 about 30nm north of Glasgow,SC (UK) when the crew decided to return to London, descended the aircraft to FL330 for the way back. On descending towards London the crew entered a hold at FL170 for about 30 minutes before landing back on Heathrow's runway 27R about 80 minutes after turning around.

An aviation service, obviously concluding from the later descent to FL170 instead of checking facts, reported the aircraft lost cabin pressure (impossible as the aircraft maintained FL330) which was parroted by global press.

A British Yellow Press even quoted a passenger as saying: "They didn't say any more. But we could hear the cabin crew talking and it turns out the pilot had to put on the oxygen mask. They had lost cabin pressure and they were worried it might spread down the plane. None of the other passengers knew but we could hear the cabin crew whispering and we were a bit nervous." (again completely impossible, including a possible problem with the crew oxygen supply, due to the fact the aircraft maintained FL330 - engineers will have a hard time to find out how it is possible the cockpit loses pressure with the cabin maintaining pressure).

The airline said, there was a minor technical problem prompting the crew to return to London as a precaution.

A replacement Boeing 777-200 registration G-VIIS is estimated to reach Seattle with a delay of 8 hours.

On Aug 14th 2015 the British AAIB released their final report concluding the probable cause of the incident was:

The problems which afflicted the flight deck ventilation on G-RAES during February 2015 and led to the events on the incident flight were almost certainly caused by the migration of debris which had accumulated in the underfloor ducting from an unknown source at a time which could not be pinpointed.

The AAIB reported that the crew became aware shortly after takeoff that the airflow from the various vents in the cockpit was very low and it became unusually warm in the cockpit, cockpit temperature control had no effect. Cabin pressure and cabin temperature were normal, there were no abnormal indications. After reaching cruise level FL340 the crew began to feel unwell, each crew member made a visit to the cabin and immediately felt relief. Contact with maintenance did not bring about a resolution of the problem. The crew therefore attempted to improve the situation in the cockpit by opening the flight deck door, the forward lavatories were removed from passenger use, curtains were closed to not let passengers see the flight deck door was open and two cabin crew were placed at the cockpit door to guard the door. The flight deck temperature dropped quickly, however, the crew did not feel relief, the first officer donned his oxygen mask and improved quickly. With the flight deck door open, one crew member on oxygen, the two others not feeling well the crew decided it was no possible to continue the flight, all crew donned their oxygen masks, closed the cockpit door and decided to return to Heathrow, where the aircraft landed safely.

Maintenance found that a large amount of debris had blocked the air distribution ducting forward of the main equipment center underneath the cockpit.