Indonesian rescuers saw bodies and luggage off the coast of Borneo island on Tuesday and officials said they were "95 percent sure" debris spotted in the sea was from a missing AirAsia plane with 162 people on board.
Indonesia AirAsia's Flight QZ8501, an Airbus A320-200, lost contact with air traffic control early on Sunday during bad weather on a flight from the Indonesian city of Surabaya to Singapore.
Pictures of floating bodies were broadcast on television and relatives of the missing gathered at the crisis centre in Surabaya were shown weeping, their heads in their hands.
Media quoted an air force official earlier as saying one suspected body, luggage and a life vest were among the debris in the Java Sea.
"As we approached, the body seemed bloated," said First Lieutenant Tri Wibowo, who was on board a Hercules aircraft, was quoted by the Kompas.com website as saying.
Search and Rescue Agency chief Soelistyo told reporters he was "95 percent sure" the debris was from the missing plane.
Djoko Murjatmodjo, acting director general of air transportation at the transportation ministry, told reporters some of the debris spotted was red and white, AirAsia's colors.
"It's probably from the aircraft," he said.
About 30 ships and 21 aircraft from Indonesia, Australia, Malaysia, Singapore, South Korea and the United States were searching up to 10,000 square nautical miles on Tuesday.
The plane, which did not issue a distress signal, disappeared after its pilot failed to get permission to fly higher to avoid bad weather because of heavy air traffic, officials said.
Pilots and aviation experts said thunderstorms, and requests to gain altitude to avoid them, were not unusual in that area.
The Indonesian pilot was experienced and the plane last underwent maintenance in mid-November, the airline said.
Online discussion among pilots has centered on unconfirmed secondary radar data from Malaysia that suggested the aircraft was climbing at a speed of 353 knots, about 100 knots too slow, and that it might have stalled.
The plane, whose engines were made by CFM International, co-owned by General Electric and Safran of France, lacked real-time engine diagnostics or monitoring, a GE spokesman said.
Such systems are mainly used on long-haul flights and can provide clues to airlines and investigators when things go wrong.
Three airline disasters involving Malaysian-affiliated carriers in less than a year have dented confidence in the country's aviation industry and spooked travelers across the region.
Malaysian Airlines Flight MH370 went missing on March 8 on a trip from Kuala Lumpur to Beijing with 239 passengers and crew on board and has not been found. On July 17, the same airline's Flight MH17 was shot down over Ukraine, killing all 298 people on board.
On board Flight QZ8501 were 155 Indonesians, three South Koreans, and one person each from Singapore, Malaysia and Britain. The co-pilot was French.
U.S. law enforcement and security officials said passenger and crew lists were being examined but nothing significant had turned up and the incident was regarded as an unexplained accident.
Indonesia AirAsia is 49 percent owned by Malaysia-based budget carrier AirAsia.
The AirAsia group, including affiliates in Thailand, the Philippines and India, had not suffered a crash since its Malaysian budget operations began in 2002.
India is waiting to know what went wrong with the missing plane and will investigate if AirAsia India is following all safety procedures, a senior Indian aviation ministry official told Reuters. AirAsia India, a joint venture of the Malaysian carrier, started flying this year and is expanding operations.
The plane's disappearance comes at a sensitive time for Indonesia's aviation authorities, as they strive to improve the country's safety reputation to match its status as one of the airline industry's fastest growing markets.