Indonesian official: Prospects bleak for missing jet

"Based on the coordinates that we know, the evaluation would be that any estimated crash position is in the sea, and that the hypothesis is the plane is at the bottom of the sea," he said.

The last communication from the cockpit to air traffic control was a request by one of the pilots to increase altitude from 32,000 feet (9,754 meters) to 38,000 feet (11,582 meters) because of the rough weather. Air traffic control was not able to immediately grant the request because another plane was in airspace at 34,000 feet, said Bambang Tjahjono, director of the state-owned company in charge of air-traffic control.

By the time clearance could be given, Flight 8501 had disappeared, Tjahjono said. The twin-engine, single-aisle plane, which never sent a distress signal, was last seen on radar four minutes after the last communication from the cockpit.

First Adm. Sigit Setiayana, the Naval Aviation Center commander at the Surabaya air force base, said 12 navy ships, five planes, three helicopters and a number of warships were taking part in the search, along with ships and planes from Singapore and Malaysia. The Australian Air Force also sent a search plane.

Searchers had to cope with heavy rain Sunday, but Setiayana said Monday that visibility was good. "God willing, we can find it soon," he said.