Urgent change needed on Air NZ's 777 flights

Air New Zealand has been told to make urgent changes to its operations and maintenance of its eight long-haul Boeing 777 aircraft in the wake of shock findings from a crash in Britain.

A British Airways jet with 152 passengers and crew crash-landed on January 17 after the engines couldn't provide enough thrust while approaching London Heathrow airport.

No one was seriously injured on the BA038 flight, but the crash ripped off wheels and cracked one wing.

Investigators have now found the crash-landing has some severe implications for long-haul routes such as those which Air New Zealand flies.

An eight-month investigation concluded that ice crystals choked off the fuel supply less than a minute before touchdown.

Engineers have no idea how many other aircraft might be vulnerable to the "previously unforeseen threat" of such blockages.

But Air New Zealand said today that new operational and maintenance requirements from aircraft maker Boeing, notified today, "will become standard operating procedure for Air New Zealand".

The general manager of airline operations, Captain David Morgan said that safety was "paramount and non-negotiable" for the airline.

"We will immediately introduce and implement these requirements from Boeing," he said.

The requirements apply only to Boeing 777 aircraft fitted with Rolls Royce Trent 800 engines.

The eight 777s operated by Air NZ have Trent engines.

British Air Accidents investigators said last night that a unique combination of three events created the conditions that choked off the fuel, and that they could not rule out the possibility of this being replicated in other aircraft.

The BA flight carried fuel at temperatures of minus-73degC in unusually cold weather over Siberia, and flew at a steady cruising speed and altitude for a long time, allowing ice to form in the fuel tanks because.

On landing, the sudden demand for a burst of fuel to the engines went unanswered as ice blocked the pipes.

Boeing spokesman Nick West said today that pilots of 777s should in future change altitude periodically when flying through very cold air, and also rev their engines before landing to clear ice from fuel lines.

The instructions cover 220 777s powered by Trent 800s in service with 11 airlines worldwide, Boeing said.

The US National Transportation Safety Board has said a design change would make the fuel system more "resilient," but would take time.

Air NZ did not directly respond to questions about the impact on its fuel-saving efforts of an requirement for planes to fly on maximum power in mid-flight to prevent the build-up of ice in fuel tanks.

The airline has recently heavily publicised its efforts to reduce fuel consumption because of the high cost of jet fuel, but will now have to ask its pilots, in motoring terms, to gun the accelerator in mid-flight.

Chief executive Rob Fyfe said recently the airline could only make a profit in the 2009 financial year if the average price of jet fuel was below $US140/barrel.

Air NZ spent over $1 billion buying four 777s planes and leasing another four in 2004.

-NZPA