Indian aviation experts feel the chances of finding the AirAsia plane which disappeared on its way from Indonesia to Singapore on Sunday are becoming bleaker with passing time.

Indonesia’s air force was searching for an AirAsia plane carrying 162 people that went missing on Sunday after the pilots asked to change course to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore.

Indonesia AirAsia Flight QZ8501, an Airbus 320-200, lost contact with Jakarta air traffic control at 6:17 a.m. (2317 GMT), officials said.

“The aircraft was on the submitted flight plan route and was requesting deviation due to en route weather before communication with the aircraft was lost,” the airline said in a statement.

According to Joko Muryo Atmodjo, air transportation director at Indonesia’s transport ministry, no distress signal had been sent.

Indian aviation expert, Harshvardhan, said pilot asking for a diversion could mean the flight developed some technical snag or was hijacked.

“As per the last communication received from the flight, it had asked for a diversion. This unusual request means that the plane was certainly experiencing some difficulty. It could be of two types, either it was experiencing some problem in its internal working or it could also have been under some pressure which can indicate towards a probable hijacking,” said Harshvardhan.

Indonesia AirAsia said there were 155 passengers and seven crew members on board. It said 156 were Indonesian, with three from South Korea and one each from Singapore, Malaysia and France.

Singapore, Malaysia and Australia had offered to help in the search. Malaysia said it was sending vessels and a C130 aircraft while Singapore had also sent a C130, officials said.

Commodore (retired) and defence and aviation expert, Ranjit Rai, doubted that the plane would have made a safe landing somewhere.

“If an accident takes place over the sea, then the pieces of a plane are scattered all over and it takes some time to ascertain the cause. I have learnt that the last SOS sent via GPS by the pilot was for a diversion. The weather was also very bad. Now we will have to see what exactly happened. But as the time is passing, I don’t see any chances of that plane having landed somewhere,” said Rai.

Meanwhile, another defence and aviation expert, Praful Bakshi, said some sort of evidence was needed to reach a sound conclusion about the fate of the plane.

“You cannot say anything directly as to what should have happened, until and unless, as a professional until I get the FDR (Flight Data Recorder) or the black box, we see the wreckage. Event the spread of the wreckage on the ground can tell you to a great deal (as to) what could have happened,” said Bakshi.

Indonesia AirAsia is 49 percent owned by Malaysia-based budget carrier AirAsia, with local investors holding the rest. The AirAsia group, including affiliates in Thailand, the Philippines and India, has not had a crash since its Malaysian budget operations began in 2002.

Flight QZ8501 was between the Indonesian port of Tanjung Pandan and the town of Pontianak, in West Kalimantan province on Borneo island, when it went missing, Atmodjo told a news conference in Jakarta.

The aircraft had been flying at 32,000 feet and had asked to fly at 38,000 feet to avoid clouds, he added.

Tanjung Pandan is the main town on Belitung island, roughly half way between Surabaya and Singapore. There was bad weather over the island at the time.

The flying time from Surabaya to Singapore is usually just over two hours. The plane had been due in Singapore at 8:30 a.m. Singapore time (0030 GMT).

In both Surabaya and Singapore, anxious relatives of people on the plane awaited news.

The airline said the captain and first officer were both experienced.

Tony Fernandes, chief of Malaysia’s AirAsia, said he was heading to Surabaya with his Indonesian management team.

“My only thought are with the passengers and my crew. We put our hope in the SAR (search and rescue) operation and thank the Indonesia, Singapore and Malaysian governments,” he said on Twitter.

The incident comes at the end of a disastrous year for the region’s airlines.

Malaysia’s national flag carrier, Malaysia Airlines, lost two aircraft this year.

Flight MH370 went missing on March 8 on a trip from Kuala Lumpur to Beijing with 239 passengers and crew on board and has still not been found.

On July 17, Flight MH17 was shot down over Ukraine, killing all 298 people on board.