Weather was the "triggering factor" in the crash of AirAsia Flight 8501 with icing likely causing engine damage, Indonesia's meteorological agency said, as divers found another body Sunday during a momentary respite from bad weather that has hampered rescue efforts.
The Airbus A320-200 crashed into the Java Sea a week ago carrying 162 people from Indonesia's second city Surabaya to Singapore, and relief workers are hunting for the "black box" flight data recorders to determine the cause of the crash.
An initial report on the website of BMKG, Indonesia's meteorological agency, suggested the weather at the time the plane went down sparked the disaster after it appeared to fly into storm clouds.
"Based on the available data received on the location of the aircraft's last contact, the weather was the triggering factor behind the accident," said the report.
"The most probable weather phenomenon was icing which can cause engine damage due to a cooling process. This is just one of the possibilities that occurred based on the analysis of existing meteorological data."
Five major parts of the Airbus A320-200 have now been found off the island of Borneo, but rough weather throughout the week has hampered the relief process, a huge operation assisted by several countries including the United States and Russia.
As the weather cleared, a team of divers went down to the biggest part of the wreckage Sunday morning and recovered one body, bringing to 31 the number of victims found, but bad conditions forced them to surface again.
"They managed to go down but the visibility at the sea bottom was zero, it was dark and the seabed was muddy, with currents of three to five knots," search and rescue agency chief Bambang Soelistyo told reporters, adding that heavy rain and big waves were continuing to hamper the rescue effort.
"For that reason, the diving efforts must be temporarily stopped. We'll try to deploy an ROV (remotely-operated underwater vehicle)," he said.
He said the fifth major part of the plane, located early Sunday, was about 10 metres by one metre (33 by 3.3 feet).
The search, focused on a patch of sea southwest of Pangkalan Bun, a town on Borneo, has also been extended east because parts of the plane may have been swept by currents, Soelistyo said.
The relief operation has prioritised finding the bodies of those on board the ill-fated flight, of whom 155 were Indonesian, with three South Koreans, one Singaporean, one Malaysian, one Briton and a Frenchman -- co-pilot Remi Plesel.
Indonesian pilot Setiawan, who is part of the ariel recovery effort combing the search area from above, told local television channel MetroTV that he had seen another three bodies floating in the sea early Sunday.
Indonesia has pledged to investigate flight violations by AirAsia, saying the ill-fated aircraft had been flying on an unauthorised schedule when it crashed. The airline has now been suspended from flying the Surabaya-Singapore route.
But the Civil Aviation Authority of Singapore said it had granted permission for the airline's Sunday flight.
It was unclear how the airline, a unit of Malaysia-based AirAsia, had been able to fly without the necessary authorisation from its starting point.
The company has declined to comment until the probe is complete, but said it would "fully cooperate" with the government.
Before take-off, the pilot of Flight 8501 had asked for permission to fly at a higher altitude to avoid the storm, but the request was not approved due to other planes above him on the popular route, according to AirNav, Indonesia's air traffic control.
In his last communication, Captain Iriyanto, an experienced former air force pilot, said he wanted to change course to avoid the menacing storm system. Then all contact was lost, about 40 minutes after the plane had taken off.
The families of victims have been preparing funerals as the bodies recovered are identified in Surabaya, where a crisis centre has been set up at a police hospital with facilities to store 150 bodies.
About 100 grieving Catholic relatives and well-wishers, some of them in tears, crowded into a small church in the police headquarters for a memorial mass Saturday afternoon, singing hymns and praying for the victims to be found quickly.
"We are trying to cope as hard as we can but it is still a very difficult time for our family as we are still waiting for news," said 25-year-old Sebastian Joseph Widodo, whose sister Florentina was on the plane.
"My faith is very central, especially at this time where there's nothing much we can do," he added.