QANTAS faced a potential disaster on Monday when a jumbo jet en route from London lost all main electrical power and was forced to land on battery back-up.
Flight QF2 with 344 passengers on board was about 15 minutes from Bangkok when the highly unusual failure took place and a back-up system kicked in.
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[email protected]With the batteries providing power for up to an hour, aviation sources said the failure would have been a disaster if it had occurred further out to sea.
"If this had happened over the ocean in the middle of the night, it would probably have crashed," an experienced 747 pilot told The Australian last night.
The near-disaster came nine years after a Qantas 747 aquaplaned off the end of the runway at Bangkok airport, crashing through navigational equipment and finishing up across a perimeter road 220m away.
The crash, Qantas's worst in 40 years, caused about $100million in damage.
Qantas chief pilot Chris Manning and the Australian Transport Safety Bureau yesterday confirmed the incident took place as the plane returned from London. "The back-up system was activated and the aircraft landed safely," Captain Manning said.
"Qantas reported the incident to Boeing, the ATSB and Civil Aviation Safety Authority and is also conducting its own thorough investigation.
"The aircraft is currently being repaired and assessed."
ATSB deputy director of aviation safety investigation Julian Walsh said investigators had been advised of the failure and had asked for flight data and cockpit voice recorders to be quarantined.
He said the ATSB was liaising with Thai authorities about who should lead the investigation. It was too early to say what had happened, he said, but he agreed the failure was "unusual".
"Obviously Qantas, Boeing and ourselves are keen to get to the bottom of it," he said.
"The information I have at the moment is that it was a total power failure."
Mr Walsh said he understood the aircraft's systems went into a degraded mode under standby power to reduce the drain on the batteries. The 747-400 has four generators, one on each engine, plus two generators on the auxiliary power unit that sources said could be linked to the main system in an emergency.
A Qantas engineer familiar with the the 747-400's electrical systems said the failure was unheard of.
He said the battery back-up and standby inverter would supply power for up to an hour.
"It's pretty dramatic if they've lost all generation systems," hesaid.
The engineer agreed the APU generators could be used in an emergency but noted that would depend on the fault that had led to the loss of power.
Another 747-400 pilot said he was aware of two other instances when the electrical systems had failed and the aircraft went to the battery back-up. "It has happened before and the aeroplane can quite comfortably cope with it for a limited period of time," he said.
Australian and International Pilots Association president Ian Woods was also surprised that the plane had lost all power. "The pilots have done a good job in dealing with a highly unusual event," he said.