Story highlights Indonesian official: "Our early conjecture is that the plane is in the bottom of the sea"

Ships, planes and helicopters search for missing commercial jet

CNN meteorologist says weather in the search area appears to be improving

Airline briefs passengers' family members at Indonesia airport

Indonesia's top rescue official says authorities believe the missing AirAsia jet is likely at the bottom of the sea, based on radar data from the plane's last contact.

"(Because) the coordinate that was given to us and the evolution from the calculation point of the flight track is at sea, our early conjecture is that the plane is in the bottom of the sea," Bambang Sulistyo, head of Indonesia's national search and rescue agency, told reporters Monday.

But searchers still don't know where the plane is, he said, and may need help from other countries for help with an underwater search.

The search for AirAsia Flight QZ8501 resumed on Monday, a day after the commercial jet disappeared in Indonesian airspace with 162 people aboard.

Ships, planes and helicopters are looking for the missing aircraft, Indonesian authorities said.

It's unclear if weather played a role in the aircraft's disappearance, but rescuers say it could be a factor that influences how quickly they find the plane.

Large waves and clouds hampered the search for the plane on Sunday, the agency said. By Monday morning, weather in the area appeared to be clearing up, CNN International meteorologist Tom Sater said.

Photos: The search for AirAsia Flight QZ8501 Photos: The search for AirAsia Flight QZ8501 Crews remove the fuselage of AirAsia Flight QZ8501 from a vessel at the Tanjung Priok Port in Jakarta, Indonesia, on Monday, March 2. AirAsia Flight QZ8501 was en route from Surabaya, Indonesia, to Singapore when it lost contact with air traffic control on December 28. There were 162 people on board. Hide Caption 1 of 47 Photos: The search for AirAsia Flight QZ8501 The fuselage is lifted from the Java Sea during the recovery mission on March 2. Hide Caption 2 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian search and rescue personnel unload recovered bodies at the Kumai seaport on Sunday, February 8. Hide Caption 3 of 47 Photos: The search for AirAsia Flight QZ8501 Workers load the tail of the plane onto a truck February 7 at the Kumai seaport. Hide Caption 4 of 47 Photos: The search for AirAsia Flight QZ8501 Crew members inspect body bags on the deck of a ship in the Java Sea on Friday, January 23. Hide Caption 5 of 47 Photos: The search for AirAsia Flight QZ8501 A police officer stands guard near pieces of the plane's wreckage at a warehouse in Pangkalan Bun, Indonesia, on Monday, January 19. Hide Caption 6 of 47 Photos: The search for AirAsia Flight QZ8501 This photo, taken by a remotely operated underwater vehicle and released Wednesday, January 14, by Singapore's Defense Ministry, shows part of the plane's fuselage lying on the floor of the Java Sea. Hide Caption 7 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian officials remove the cockpit voice recorder from AirAsia Flight QZ8501 on Tuesday, January 13. Indonesian divers retrieved it from beneath the wreckage of the plane. Hide Caption 8 of 47 Photos: The search for AirAsia Flight QZ8501 A flight data recorder was retrieved from the Java Sea on Monday, January 12. Hide Caption 9 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian worker cuts part of the plane's tail January 12 after debris from the crash was retrieved from the Java Sea. Hide Caption 10 of 47 Photos: The search for AirAsia Flight QZ8501 A portion of the plane's tail section is seen on the deck of a rescue ship after it was recovered from the Java Sea on Saturday, January 10. Hide Caption 11 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian rescue helicopter flies during search operations in the Java Sea on Friday, January 9. Hide Caption 12 of 47 Photos: The search for AirAsia Flight QZ8501 Search personnel unload the body of a victim upon arriving at the airport in Pangkalan Bun on January 9. Hide Caption 13 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Indonesian Search and Rescue Agency carry pieces of the jet in Pangkalan Bun on January 9. Hide Caption 14 of 47 Photos: The search for AirAsia Flight QZ8501 There was a major breakthrough in the search for the wreckage on Wednesday, January 7. Indonesian search and rescue officials released an image of the plane's tail section as seen on the floor of the Java Sea. Hide Caption 15 of 47 Photos: The search for AirAsia Flight QZ8501 Writing could be made out, showing the AirAsia insignia and other identifying features. The find is important because the plane's flight recorders were located in the tail section. Hide Caption 16 of 47 Photos: The search for AirAsia Flight QZ8501 Divers were sent to take images of the section after metal detectors identified large objects in the water where officials were searching for the lost plane. Hide Caption 17 of 47 Photos: The search for AirAsia Flight QZ8501 Search and rescue personnel carry seats from the flight on Monday, January 5. Hide Caption 18 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian navy member holds a piece of window panel that was recovered during search operations. Hide Caption 19 of 47 Photos: The search for AirAsia Flight QZ8501 Crew members in an Indonesian air force helicopter look out of the windows over the Java Sea during a search operation on Sunday, January 4. Hide Caption 20 of 47 Photos: The search for AirAsia Flight QZ8501 Members of an Indonesian search and rescue team carry items recovered from the search area in Pangkalan Bun on January 4. Hide Caption 21 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Mawar Sharon Church attend a prayer service for the relatives of lost loved ones January 4 in Surabaya, Indonesia. Hide Caption 22 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian navy officers coordinate the recovery of bodies taken to the vessel KRI Banda Aceh during recovery operations on Saturday, January 3. Hide Caption 23 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the Indonesian navy return to the vessel with remains recovered from the crash area. Hide Caption 24 of 47 Photos: The search for AirAsia Flight QZ8501 Recovered victims are placed on the deck of the Indonesian ship on January 3. Hide Caption 25 of 47 Photos: The search for AirAsia Flight QZ8501 Members of an Indonesian search team carry a coffin at Iskandar Air Base on Friday, January 2. Hide Caption 26 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives and friends grieve as they attend a ceremony January 2 in Surabaya. Hide Caption 27 of 47 Photos: The search for AirAsia Flight QZ8501 A member of the Indonesian Red Cross prepares coffins at a hospital in Pangkalan Bun on January 2. Hide Caption 28 of 47 Photos: The search for AirAsia Flight QZ8501 Members of the National Search and Rescue Agency and Indonesian soldiers carry coffins containing bodies of victims in Pangkalan Bun on January 2. Hide Caption 29 of 47 Photos: The search for AirAsia Flight QZ8501 This photograph released by the Singapore Defense Ministry shows the front and back of a piece of debris that resembles an aircraft window panel. Hide Caption 30 of 47 Photos: The search for AirAsia Flight QZ8501 Members of a search and rescue team carry the body of a victim in Pangkalan Bun on Thursday, January 1. Hide Caption 31 of 47 Photos: The search for AirAsia Flight QZ8501 Marine divers prepare their gear on the deck of a ship before searching for passengers and debris January 1 at Kumai port in Pangkalan Bun. Hide Caption 32 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian soldiers carry a victim's coffin upon arrival at an air force base in Surabaya on Wednesday, December 31. Hide Caption 33 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian soldiers carry coffins of crash victims on December 31. Hide Caption 34 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives of passengers pray together inside a holding room at Juanda International Airport in Surabaya on December 31. Hide Caption 35 of 47 Photos: The search for AirAsia Flight QZ8501 Indonesian air force personnel show debris, including a suitcase, that was found floating near the site where the AirAsia flight disappeared. Hide Caption 36 of 47 Photos: The search for AirAsia Flight QZ8501 Debris floats in the Java Sea on December 30. Hide Caption 37 of 47 Photos: The search for AirAsia Flight QZ8501 A member of the Indonesian navy monitors a radar screen during a search operation over the waters near Bangka Island, Indonesia, on December 30. Hide Caption 38 of 47 Photos: The search for AirAsia Flight QZ8501 Family members of missing passengers react at an airport in Surabaya after watching news reports on December 30. Hide Caption 39 of 47 Photos: The search for AirAsia Flight QZ8501 Debris floats in the Java Sea on December 30. Hide Caption 40 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives of missing passengers comfort each other December 30 at Juanda International Airport in Surabaya. Hide Caption 41 of 47 Photos: The search for AirAsia Flight QZ8501 Relatives gather at Juanda International Airport as they wait for news on December 30. Hide Caption 42 of 47 Photos: The search for AirAsia Flight QZ8501 An Indonesian military airman looks out the window of an airplane during a search over the waters of Karimata Strait on Monday, December 29. Hide Caption 43 of 47 Photos: The search for AirAsia Flight QZ8501 Members of Indonesia's Marine Police pray before a search operation on December 29. Hide Caption 44 of 47 Photos: The search for AirAsia Flight QZ8501 Military personnel perform a search operation on Sunday, December 28. Hide Caption 45 of 47 Photos: The search for AirAsia Flight QZ8501 Sunu Widyatmoko, CEO of Indonesia AirAsia, gives a press conference in Surabaya announcing that the flight lost contact with air traffic control. Hide Caption 46 of 47 Photos: The search for AirAsia Flight QZ8501 An official from Indonesia's national search and rescue agency points to the position where AirAsia Flight QZ8501 went missing. Hide Caption 47 of 47

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Authorities say they're combing a "very broad search area."

AirAsia says air traffic controllers lost contact with the aircraft at 7:24 a.m. Sunday Singapore time (6:24 a.m. in Indonesia).

The missing plane, flying from the Indonesian city of Surabaya to Singapore, went missing as it flew over the Java Sea between the islands of Belitung and Borneo -- a heavily traveled shipping channel with shallow waters, according to Indonesian authorities, who are leading the search and rescue operations.

Before the plane lost contact with air traffic controllers, one of the pilots asked to fly at a higher altitude because of bad weather , officials said.

In addition to Indonesia's teams, several other countries have joined the hunt for the missing plane.

A C-130 plane from Singapore has been participating in the search, and the country's military says it's sending two more ships to the search area. Malaysia's transportation minister said his country has deployed three vessels and three aircraft to assist in the search. And the Royal Australian Air Force said Monday that it was deploying a patrol plane to help.

And Indonesia has reached out to the United Kingdom, France and the United States for help with sonar technology that may be needed for an underwater search, Sulistyo told reporters Monday.

Now that a day has passed since the plane went missing, investigators should have more data to help them find it, said Peter Goelz, former managing director of the U.S. National Transportation Safety Board.

"They've had a full 24 hours now to gather all of the available radar data from all of the available sources," he said. "They should be able to put that together, along with any satellite data, and have a more precise location on where to target their search."

Waiting and weeping

After hours of waiting in anguish for any word about the passengers aboard the missing plane, several dozen of their family members met with airport and airline officials in a closed-door briefing Monday at the airport in Surabaya.

As they waited for news before the briefing, some took cell phone pictures of a flight manifest posted on a wall. The black-and-white papers showed every passenger's name and seat number, but not their fate.

Others simply sat and dabbed tears from their eyes.

"Our concern right now is for the relatives and the next of kin," AirAsia CEO Tony Fernandes said during a news conference in Surabaya. He confirmed that storm clouds caused the pilot to ask for a change in flight plan, but added, "We don't want to speculate whether weather was a factor. We really don't know." Once the aircraft is found, there will be a proper investigation, Fernandes said.

Of the people on board the Airbus A320-200, 155 are Indonesian, three are South Korean, one is British, one is French, one is Malaysian and one is Singaporean, the airline said.

Eighteen children, including one infant, are among the passengers, the carrier said. Seven of the people on board are crew members.

Questions over pilots' communications

Flight 8501 "was requesting deviation due to en route weather before communication with the aircraft was lost," the airline said.

The flight's captain asked permission to climb to a higher altitude, the Indonesian Transportation Ministry's acting director general for air transportation affairs, Djoko Murdjatmojo, said, according to the national news agency.

According to flight tracking websites, almost the entire flight path of the plane was over the sea.

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CNN aviation analyst Mary Schiavo said that if there was an onboard emergency, the pilots should have issued a mayday call or a pan-pan call.

"Mayday means you're immediately in danger of losing the flight; pan-pan means that it is urgent but that you can continue the flight and request an alternate route or an alternate airport," said Schiavo, a former inspector general for the U.S. Department of Transportation.

"It's disconcerting in that the standard procedures for an emergency don't seem to have been deployed," she said.

But Alan Diehl, a former Air Force and NTSB accident investigator, said pilots don't always make mayday calls in an emergency.

"You know that the controllers can't really help you," he told CNN. "You and your co-pilot are going to have to solve this."

It's too soon to know what happened to the missing plane, he said. Details released so far show some similarities, Diehl said, with an Air Algerie flight that disintegrated and crashed in July after changing its flight path because of bad weather.

But there's also a chance that the AirAsia flight didn't crash after losing contact with air traffic control, he said.

The Airbus A320 is equipped with a ditching switch, Diehl said, that essentially turns the plane's fuselage into a boat.

"If they got the aircraft down on the water safely," he said, "it should be floating."

'Very good' safety reputation

As word spread of the missing plane, the airline changed the color of its logo on its website and social media accounts from red to gray.

Indonesia's President Joko Widodo said his nation was "praying for the safety" of those on board. Pope Francis also prayed for the missing, according to Vatican Radio.

AirAsia is a Malaysia-based airline that is popular in the region as a budget carrier. It travels to about 100 destinations, with affiliate companies in several Asian countries.

The missing plane is operated by AirAsia's Indonesian affiliate, in which the Malaysian company holds a 48.9% stake, according to its website.

AirAsia has a "very good" reputation for safety, CNN aviation correspondent Richard Quest said.

Flight 8501's captain has a total of 20,537 flying hours, with 6,100 of them with AirAsia Indonesia on the Airbus A320, the airline said. The first officer has a total of 2,275 flying hours, AirAsia said. The plane's last scheduled maintenance was on November 16, it said.

The French Foreign Ministry said the first officer is the French citizen who is on the plane. A state-run company in Indonesia that manages airports identified the first officer as Remi Emmanuel Plesel.

Airbus said the plane had "accumulated approximately 23,000 flight hours in some 13,600 flights." The aircraft manufacturer said it would provide full assistance to authorities in charge of investigating the missing plane.

The loss of contact with the AirAsia plane comes nearly 10 months after the disappearance of Malaysia Airlines Flight 370, which dropped off radar over Southeast Asia on March 8 with 239 people on board.

The Malaysia Airlines plane, a Boeing 777-200ER, lost contact with air traffic control over the South China Sea between Malaysia and Vietnam.

Searchers have yet to find any debris from Flight 370, which officials believe crashed in the southern Indian Ocean after veering dramatically off course.

But some aviation experts don't think the search for Flight 8501 will be as grueling as the search for MH370.

"We are not talking about the deep Indian Ocean here," Quest said. "We are talking about congested airspace around Southeast Asia. There will be much better radar coverage. There's certainly better air traffic control coverage."