As they resumed the search for the missing AirAsia plane Monday morning, Indonesian authorities said they believe the commercial jet with 162 people on board already lies at the bottom of the sea.

Indonesia’s National Search and Rescue Agency chief Bambang Soelistyo at a press conference called it a “preliminary suspicion” based on last coordinates and the estimated crash position.

Soelistyo said Indonesia lacks the equipment needed to find and retrieve a plane from such depths and has reached out to other countries. Among the countries who have offered help with the technology needed are the United States, the United Kingdom and France.

The plane, an Airbus A320-200, had encountered a string of intense thunderstorms and heavy clouds Sunday morning over the Java Sea. Hoping to avoid the worst of the weather, the pilot radioed in a request to climb from 32,000 feet to 38,000 feet, an Indonesian Transport Ministry official, Djoko Murjatmodjo, said at an earlier news conference.

Indonesian air-traffic controllers apparently denied the request for a higher altitude, just minutes before the plane disappeared from their screens Sunday without a distress call. Controllers at first gave the pilot the okay but then reversed themselves because of other air traffic in the vicinity, including a flight above his, Murjatmodjo told Kompas, a leading Indonesian newspaper.

The plane’s disappearance was the third air crisis this year for Southeast Asia — and an eerily familiar one, just nine months after a Malaysia Airlines jetliner disappeared over the Indian Ocean. That plane, with 239 people on board, is still lost. Another Malaysia Airlines jet was shot down over eastern Ukraine in July, killing all 298 people aboard.

On Sunday, Malaysia Airlines posted a message on its Twitter account: “#staystrong @AirAsia — Our thoughts and prayers are with all family and friends of those onboard QZ8501.”

The AirAsia flight took off from the Indonesian city of Surabaya and was scheduled to land in Singapore at 8:30 a.m. Sunday. Almost all the passengers and crew members were indonesians.

An Indonesian admiral, Sigit Setiayana, said Monday morning that more than a dozen naval vessels, five airplanes and three helicopters had resumed the search for the plane in an area east and southeast of Belitung island, with good visibility, the AP reported.

“God willing, we can find it soon,” he said.

Darkness and bad weather had forced the rescue agency to call off search efforts Sunday evening.

Instead of welcoming their loved ones Sunday morning, anguished and terrified relatives and friends gathered in crisis centers set up inside Juanda International Airport in Indonesia and Changi Airport in Singapore, desperately awaiting word of the lost plane.

It immediately brought to mind similar gatherings in Malaysia’s capital, Kuala Lumpur, and in Beijing this past spring, when the first Malaysia Airlines plane vanished.

Thousands of people across the world expressed support Sunday on Twitter and Facebook, or captured the shock with the message “Not again.” Pope Francis prayed for the missing, according to Vatican Radio. Indonesian President Joko Widodo said his nation was “praying for the safety” of those on board.

Sunday afternoon, AirAsia changed the color of its logo on its Web site and social-media accounts from a festive holiday design to a shrouded, all-black bar.

The airline’s chief executive, Tony Fernandes, flew to Surabaya and later told a news briefing: “We are very devastated by what’s happened; it’s unbelievable.”

While no one was sure if weather was the cause of the disappearance, it probably complicated things, according to AccuWeather.com meteorologist Alex Sosnowski, who said, “The storms in the area were capable of producing severe turbulence, strong wind shear, frequent lightning and icing.” December and January are the wettest months in Indonesia.

Aviation experts could only speculate as to why there was no distress call. One likely possibility was that a sudden and probably catastrophic depressurization incapacitated the pilots or the communications equipment.

Radar showed that just before it disappeared, the plane was flying at a relatively low speed, less than 500 mph, the BBC reported.

“Our concern right now is for the relatives and for the next of kin — there is nothing more important to us, for our crew’s family and for the passengers’ families,” Fernandes said.

Those family members were rattled and in a state of panic.

Nias Adityas, a housewife from Surabaya, wept when she found the name of her husband, Nanang Priowidodo, 43, on the list of passengers. He was a tour guide and had been hired to take a family of four on a trip. He had been relieved and happy to get the work.

“He just told me, ‘Praise God, this new year brings a lot of good fortune,’ ” Adityas told reporters gathered at the airport. “He apologized because he could not join us for the new year celebration.”

Louise Sidharta, 25, of Indonesia told the media that she was awaiting news of her fiance, a 27-year-old entrepreneur named Alain, who she said was on the flight along with five family members. She had taken a later flight from Surabaya to Singapore and found out about the missing aircraft upon arriving, Agence France-Presse reported.

“This was supposed to be his last trip with his family before we got married,” she said.

The flight lost contact at 6:17 a.m. local time (6:17 p.m. Saturday in Washington). The break in communications occurred 42 minutes after takeoff and roughly an hour before the scheduled landing at Changi Airport, Indonesian authorities said.

By Sunday evening, there had been no sign of any wreckage.

The rescue agency said it will divide the search area into four broad sections measuring 120 by 240 nautical miles. The search may also extend to nearby land.

Malaysia will send three vessels, and Singapore will add at least one search plane, according to rescue officials. Australia and India also offered assistance.

AirAsia is a budget airline based in Malaysia, although the missing jet belongs to its Indonesian affiliate. AirAsia, bought and relaunched in 2001 by Fernandes, had never had a fatal accident. Over the past decade, it became a strong regional competitor, with short flights and cheap tickets throughout Southeast Asia.

In a written statement, AirAsia said the captain of Flight QZ8501 was experienced, with “a total of 20,537 flying hours of which, 6,100 flying hours were with AirAsia Indonesia.” It said the first officer had a total of 2,275 flying hours with AirAsia Indonesia.

The airline added that the plane underwent “its last scheduled maintenance” on Nov. 16.

In a statement early Sunday, the plane’s manufacturer, Airbus, said that it is assisting with the investigation and that the jet had accumulated about 23,000 flight hours during about 13,600 flights.

Although Indonesian officials placed the lost contact at 6:17 a.m., Singapore authorities and AirAsia in initial statements placed it at 6:24 a.m. — a discrepancy that has not been explained.

The flight took off with 155 passengers, two pilots, one engineer and four flight attendants, according to AirAsia. All but seven passengers and crew members were Indonesian, the airline said; three were South Korean, and there were individuals from Malaysia, Singapore and Britain on board. The co-pilot was French, according to France’s Foreign Ministry. The passengers included 16 children and one infant.

Malaysian Prime Minister Najib Razak tweeted: “Very sad to hear that AirAsia Indonesia QZ8501 is missing. My thoughts are with the families. Malaysia stands ready to help.”

White House spokesman Eric Schultz said President Obama, who is on vacation in Hawaii, “has been briefed on AirAsia Flight 8501, and White House officials will continue to monitor the situation.”

Secretary of State John F. Kerry, in a tweet, said, “Our hearts and hopes are with the passengers and families of AirAsia QZ8501.”

A spokesman for the U.S. National Transportation Safety Board, Terry Williams, said, “We are aware of the missing airplane and are monitoring the situation.” Williams said that, if asked, the agency would provide assistance to investigators.

Wax-Thibodeaux reported from Washington.