Airline safety review

 

TAM Airlines A320 crash, Rex Features
 © Rex Features
The TAM Airbus A320 overrun led to alert modifications

 

Below are brief synopses of accident reports published in the last six months of 2010. For those published in the first half of the year, see the report in Flight International, 3-9 August 2010.

  • On 7 January 2008, a Qantas Boeing 747-400 (VH-OJM) suffered a major electrical power failure on approach to Bangkok resulting from a "substantial water leak" in the forward galley area. The Australian Transport Safety Bureau urged Boeing to update its flight handbook to help crew with decisions during an electrical power loss. The ATSB said the leak came from an overflowing drain when a drain line became blocked with ice that had formed because of an inoperable heater. "The water flowed forward and through a decompression panel into the aircraft's main equipment centre before leaking on to three of the four generator units, causing them to malfunction and shut down." A drip-tray failed to shield the electric systems from the spillage. The aircraft landed safely. The 346 passengers and 19 crew on board were uninjured.

On 25 July 2008, one of the bank of oxygen cylinders sited in the cargo hold of a Qantas Boeing 747-400 (VH-OJK) failed at its base. The explosion ruptured the fuselage and the pressurised gas projected the cylinder up through the floor into a galley area, damaging an external door. The aircraft, en route from Hong Kong to Melbourne, suffered sudden decompression, so the crew descended to 10,000ft (3,000m) and diverted to Manila, Philippines. Nobody was hurt. The ATSB has not determined the reason for the cylinder's failure.

  • The 27 November 2008 crash of an XL Airways Airbus A320 offshore from Perpignan, France, during a post-maintenance test flight was caused by icing affecting the twinjet's angle-of-attack sensors, combined with the crew's complete lack of test flying experience, and the captain disregarding operational guidelines for the safe performance of low-speed handling checks. French investigation agency BEA attributed the icing to maintenance company EAS Industries' failure to protect the sensors during water washing.

This meant the crew did not receive correct stall warning and protection during the low-speed handling test, which they carried out during descent toward Perpignan when passing 4,000ft. Air traffic control restrictions prevented them carrying out the test manoeuvres they wanted to, so they tried to carry out the low-speed checks during descent, despite the fact that the Airbus procedures they were supposed to be following demand such tests are not carried out below 14,000ft. The crew lost control of the aircraft when it stalled, and could not recover before hitting the sea.

  • Spanish legal procedures are preventing technical investigators checking electrical equipment that played a vital part in the 20 August 2008 crash of a Spanair Boeing MD-82 during take-off from Madrid Barajas airport. The pilots inadvertently failed to set take-off flap, did not realise their omission, and lost control of the aircraft. The crash killed 154 passengers and crew.

What should have been a relatively minor electrical relay fault with the ram air temperature probe heating system mysteriously disabled the take-off configuration warning system that would have alerted the crew to their error as soon as they set take-off power, but the Spanish judiciary is stopping investigators examining the systems to establish the connection between the relay failure and the absence of the take-off configuration warning.

  • In a follow-up to the Brazilian report on the 17 July 2007 fatal overrun by a TAM Airbus A320 at São Paulo Congonhas airport, the European Aviation Safety Agency is issuing an airworthiness directive requiring modification to the system that generates the throttle lever "retard" warning on touchdown. The overrun occurred for a variety of reasons but, most importantly, at touchdown the pilots failed to retard both the throttle levers to idle. With the existing system, the recorded voice message to "retard" the throttles would stop if one lever was selected to reverse, even if the other was not retarded to idle. With the modification, as long as one thrust lever remains above idle, the call to "retard" will continue.