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The crew of Air New Zealand's doomed Airbus jet were last night being hailed as heroes - a witness believes they saved dozens of lives by crashing the plane into the sea to avoid a small French town.

As the shattered jet lies in 20,000 pieces in the Mediterranean, new details began to emerge of the final seconds, including one witness report of a catastrophic engine failure.

"When the aircraft was over Canet, the pilot tried to restart it and it picked up," retired aviation mechanic Claude Pedro told Perpignan's L'Independant newspaper. "It ascended and then cut out. That was it, then nothing. It fell. I can tell you it was only flying on one engine, I'm sure of that, I would have heard the sound of the second. And with only one engine there was nothing to be done.

"What is certain, is that the aircraft could easily have crashed and fallen on Canet. I think that pilot really wanted to avoid the town and risk to the inhabitants, which is why he really pushed it. In some way, they sacrificed their lives to save others and to try to save the aircraft."

He said that once past the populated areas, the crew would have been able to descend to try to splash down but the aircraft probably "gave up".

According to several witnesses, it pitched in every direction before plunging into the ocean.

New Zealand-based aviation experts also speculated there was a catastrophic mechanical error on the German-operated plane. But questions remain over the final seconds - the pilots apparently had no time to correct the problem or issue a mayday.

A team of 10 divers last night returned to the crash site to try to retrieve the aircraft's two flight recorders, which are expected to yield significant clues to the cause of the crash. Air New Zealand urged the public and aviation industry to avoid speculating on possible causes until proper evidence emerged.

Five Kiwis - including four Air New Zealand staff - and the two German pilots were killed when the Airbus plunged into the Mediterranean, 3km from the French coast near Perpignan. Le Monde newspaper reported last night that three bodies have now been recovered, although search efforts are being hampered by bad weather and rough seas.

One experienced New Zealand pilot, speaking on condition of anonymity, had three theories: the plane either hit something, such as a bird; lost a vital piece of equipment such as an aileron or wing panel; or a mechanical defect brought the plane down. Another theory was that the wing flaps may not have deployed properly for the landing, causing the aircraft to bank suddenly to the right.

Air New Zealand chief executive Rob Fyfe arrived in Perpignan early today, following a 28-hour flight through Hong Kong and Heathrow with the partner and another family member of one of the victims, Murray White. There had been "a lot of tears, a few laughs, and a lot of sharing" on the flight to Europe, he said.

"It's bloody tough. I have sat next to them on the flight up to Hong Kong, and up to London," he told the Herald on Sunday. "We have got a team on board - there's police here, a TAIC [Transport Accident Investigation Commission] expert, people from the CAA [Civil Aviation Authority]. We have set aside space in the business class cabin. There's a real sense of team spirit developing, but also trepidation about what we are going to find when we get on the ground."

Family members of another victim flew out last night and a third family was leaving for France today.

Fyfe said he had received about 300 emails of condolence in the hours after the tragedy from staff, other airline CEOs, and members of the public, each of whom he was hoping to respond to by the time he arrived in France. He had also spent about four or five hours on a satellite phone on the flight to Hong Kong, liaising with senior management and families.

Fyfe had not seen photographs of the jet's koru fin floating in the water - an image eerily similar to an infamous Erebus crash photograph. "The aircraft was owned by Air New Zealand and was operated by another airline. Tragically, a number of our people were on board. XL was operating it. It's a tragedy and the fact there is imagery linking Air New Zealand, undoubtedly that connects the emotion to people, as much those inside the company as those outside."

He said the airline had not received any indication of the cause of the crash.