A computer software program on board an Air Transat plane that ran out of fuel over the Atlantic likely gave the cockpit crew inaccurate information about what was happening to the jetliner as it lost both engines and was forced to make an emergency landing, says the lead investigator.

Officials with the Portuguese transportation safety board, the lead agency in the investigation, is focusing part of its probe on software that indicates to the crew how the aircraft's systems are functioning.

FUEL LEAK INTERPRETED

They suspect the program interpreted a fuel leak as a fuel imbalance, leading the crew to respond differently to the crisis aboard the massive Airbus A330 as it quickly lost all of its fuel and glided to a terrifying landing in the Azores last August.

"What we're discussing very carefully is whether the information provided by the computer to the crew is the best information to deal with the problem, and we have some serious doubts with that," Frederico Serra said in an interview from Lisbon, Portugal.

"There is something wrong with this system. There is something that was not given to the crew on time."

Investigators say it was too late when the crew detected the leak for them to try to diminish its seriousness.

They also suspect an automatic function on the aircraft that corrects fuel imbalances - when there is more fuel in one tank than the other - could have made the situation worse.

The computer interpreted the fuel leak as a fuel imbalance, possibly triggering the mechanism to divert fuel to the leaking tank and emptying the other one. The pilot also could have initiated the feeding of fuel from the full to empty tank.

Serra, who's being assisted by the Canadian Transportation Safety Board, said the software program collects data on what's happening to the aircraft's different systems, analyses it and provides an output, or an interpretation of those events. The pilot and co-pilot then consult a manual of procedures on how to deal with different scenarios.

"We need to know if the output was the best to deal with the problem," he said. "We have big doubts in that."

Serra said he didn't think the fleet would have to be grounded if the software is confirmed to be faulty.

A spokesman for Airbus Industrie in Toulouse, France, would not comment on the computer system.

ONLY LAND FOR 1,600 KILOMETRES

Air Transat's Flight 236, with 291 passengers and a crew of 13 on an overnight journey from Toronto to Lisbon, made the emergency "dead-stick" landing on Aug. 24 at a military air base in the Portuguese islands of the Azores, the only land for more than 1,600 kilometres in any direction.

The crew declared an emergency when the right engine failed after running out of fuel. About 13 minutes later, the left engine failed and the crew prepared to ditch at sea.

"It was too late that the pilots noticed that the fuel was missing and they didn't realize why or where was the cause of the missing fuel," Serra said. "They confirmed there was a leak when the first engine shut down, some moments later from that they tried to manage to get all the fuel for the remaining engine.

"The computer didn't provide to them the best information."

Investigators have already determined that mechanics in Montreal didn't follow recommended procedures when they replaced the jet's engine using a component from a newer engine. The engine's manufacturer, Rolls Royce, had recommended the parts not be swapped.

The replacement engine on the Airbus A330 was missing a hydraulic pump and mechanics used a pump from a newer engine.

The airline was slapped with a $250,000 fine, the biggest in Canadian aviation history, for the maintenance infraction, and passengers are suing for $30 million.

Canoe

-- Anonymous, January 28, 2002