The missing AirAsia flight QZ8501 carrying 162 people to Singapore from Surabaya is thought to have crashed into the sea, a senior Indonesian rescue agency official told Reuters on Monday.

"Based on our coordinates, we expect it is in the sea, so for now (we think) it is on the sea floor," said Soelistyo, head of Indonesia's search and rescue agency, according to the Reuters report.

The search for the aircraft resumed at 6 a.m. local time (2300 GMT) on Monday as grieving relatives await clarity on the fate of the airplane.

Search and rescue operations for the plane that disappeared early Sunday were halted at nightfall. At the time the search was suspended, no debris had been found.

Search operations in the Java Sea are being led by Indonesia with Singapore, Malaysia and Australia aiding in the efforts.

Twelve navy ships, five planes, three helicopters and a number of warships were talking part, along with assets from the three neighboring countries, First Admiral Sigit Setiayana, the Naval Aviation Center commander at the Surabaya air force base told the Associated Press.

"God willing, we can find it soon," Setiayana said, noting that visibility was good.

The plane is believed to have gone missing somewhere in the Java Sea between Tanjung Pandan on Belitung island and Pontianak in West Kalimantan.

The Airbus A320-200, which departed the Indonesian city of Surabaya around 5:35 a.m. local time (2235 GMT), lost contact with air traffic control about 42 minutes after takeoff. The flight normally takes around two hours.

The aircraft was on its planned route and was requesting deviation due to enroute weather before communication was lost, AirAsia said in a statement. No distress signal was sent, Joko Muryo Atmodjo, air transportation director at Indonesia's transport ministry, told Reuters.

There were 155 passengers - 138 adults, 16 children and 1 infant - and seven crew members on board the flight. The overwhelming bulk of those on board were Indonesian, with three from South Korea, one from Singapore, one from Malaysia, one from the U.K. and one from France, according to AirAsia.

The captain in command, identified as Irianto, had a total of 20,537 flying hours of which 6,100 were with AirAsia Indonesia on the Airbus A320. The first officer had a total of 2,275 flying hours with AirAsia Indonesia.

<p>Search set to resume for missing AirAsia jet</p> <p>The search for missing AirAsia flight QZ8501 was set to resume at first light on Monday. The jet bound to Singapore from Indonesia vanished from air traffic radar early Sunday. CNBC&#039;s Sri Jegarajah has more.</p>

The plane's disappearance marks the third airline disaster linked to Malaysia this year, capping a string of commercial air tragedies this year.

Possible scenario

Peter Reiss, former security consultant to The International Civil Aviation Organization and former pilot for Northwest Airlines for 35 years said the main scenario that comes to his mind is the aircraft entered an "extremely violent" weather event that threw it out of control.

"I would be very interested to know what simulator training AirAsia Airbus pilots get," he said. "In my 35 years of flying for the airline, I only encountered a couple of severe turbulence instances and the training I had stood solidly for me."

Subhranshu Sekhar Das, head of aerospace, defense & security practice, Asia-Pacific, at Frost and Sullivan believed the Airbus A320-200 was equipped with sophisticated radar equipment, but not the latest equipment.

AirAsia has not yet commented on the possible cause of the plane's disappearance.

"We have no idea at the moment what went wrong," CEO Tony Fernandes said at a press conference on Sunday."Let's not speculate at the moment."

Since its founding in 2001, the Malaysia-based low cost carrier has had a good safety record, with no fatal accidents involving its aircraft.

Families await news

The management of AirAsia along with the governor of East Java, the National Search and Rescue Agency of Republic of Indonesia, the Airport Authority of Indonesia and the airport operator met with the members of the families in Surabaya on Sunday to update them on the latest developments.

"We are deeply shocked and saddened by this incident. We are cooperating with the relevant authorities to the fullest extent to determine the cause of this incident," Sunu Widyatmoko, CEO of AirAsia Indonesia, said.

"Our main priority is keeping the families of our passengers and colleagues informed on the latest development. We will do everything possible to support them as the investigation continues and have already mobilized a support team to help take care of their immediate needs, including accommodation and travel arrangements," he said.

16 next-of-kins took the offer to fly from Singapore to Surabaya Sunday night, according to a statement from Changi Airport Group.

Crisis centers have been set up in Surabaya and Singapore to support to friends and family members.

Sunu Widyatmoko, CEO of AirAsia Indonesia is currently stationed at the center in Surabaya.

CNBC