Wednesday, 25 July 2018

Poor preflight checks caused Malaysia Airlines flight to depart with covered pitot tubes.

A Malaysian Airlines Airbus A330 departed Brisbane Airport in Australia at 23.18 on the 18th of July this year, yet as the aircraft climbed away from the airport, the crew couldn't tell how fast the aircraft was going.

The flight deck crew were alarmed and declared a 'Pan Pan Pan' alert advising air traffic control that they had an issue. It appeared to them that all the airspeed indicators had failed during the take-off phase of the flight. The crew decided to return to Brisbane airport but first jettisoned some fuel to lighten the aircraft to a safe landing weight.

There were 226 passengers on the aircraft, 9M-MTK, who had been hoping to go to Kuala Lumpur as scheduled but were told they were returning to Brisbane. The aircraft made a safe, but heavy fast landing at Brisbane and passengers were able to disembark the aircraft.

Initial investigations suggest that four plastic protective covers that are put on the sensitive pitot tubes to prevent dirt, insects or other debris to enter the tube and cause a blockage had mistakenly been left in place. These plastic covers should always be removed prior to a flight, while the aircraft is still at its parking stand or departure gate. The pitot tubes are essential for providing the airspeed once the aircraft is flying, so it is essential these are kept clear and free of obstruction. The A330 like all commercial jet aircraft have a number of them fitted to the front of the aircraft, to proved redundancy should one become blocked or otherwise malfunction. 

The initial inspection found that these plastic covers had melted in the tubes causing a blockage, leading to no speed readings being received in the cockpit while the aircraft was in the air.  Quite how the big red pitot tube protective covers could remain in place unseen during preflight inspections is unknown at this stage.

It is understood that an Australian engineering company that handles Malaysian at Brisbane should have done a preflight inspection. A walk around check is also usually done by a member of the flight deck crew to ensure such things are cleared and the aircraft safe to fly.

The Australian Transport Safety Bureau has said an investigation into who was to blame was ongoing and would be reported in due course when all fact are known. The Airbus A330 was grounded at Brisbane following the incident, which also caused damage to a wheel during the heavy landing as well as the blocked pitot tubes and it is understood the aircraft is still at Brisbane.