JAKARTA, Jan. 4-- Weather was believed a "triggering factor" in the crash of AirAsia Flight 8501 into the Java Sea with 162 people on board en route from Indonesia's Surabaya to Singapore, Indonesia's meteorological agency said in a report posted on its website Sunday.

"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," it said.

It remains unclear what caused the plane to crash into the sea, but bad weather appeared to have been a "triggering factor," said the report. The aircraft appeared to have flown into storm clouds, the report noted.

As weather appeared improving, divers prepared Sunday to examine wreckage of AirAsia Flight 8501, hoping to retrieve the rest of the bodies and find clues to what caused the plane to crash in stormy weather a week ago.

The breakthrough in the search operation came after major parts of the Airbus A320-200 were found in the sea off the island of Borneo late Friday and Saturday. The biggest piece, measuring 18 meters long and 5.4 meters wide, appeared to be part of the jet 's body, said a senior official of Indonesia's National Search and Rescue Agency.

While the plane's black boxes, the flight data and cockpit voice recorders, have yet to be located, the discovery of the wreckage, especially if it is largely intact, would greatly benefit the probe, aviation experts noted.