After two days of searching, officials have yet to find any trace of an AirAsia flight which went missing on Sunday with 162 people aboard. Here's a look at what we know about the airliner, how it disappeared and efforts to find the missing plane.
When was the plane last heard from?
AirAsia flight QZ8501 was en route from Indonesia to Singapore and flying at 32,000 feet above the Java Sea on Sunday morning when one of its pilots requested to change course because of bad weather. Bambang Tjahjono, director of the state-owned company in charge of air-traffic control, told The Associated Press that air traffic controllers were not immediately able to grant this request because another aircraft was in the same airspace. By the time it had been given clearance, just four minutes after its last correspondence, the jet had disappeared from radar, Tjahjono told the news agency.
Who was on board the missing flight?
The aircraft had 155 passengers, two pilots, one engineer and four cabin crew. Aside from Indonesian nationals, three were from South Korea and one each from Singapore, Malaysia, Britain and France. Seventeen passengers were children and one was an infant, according to AirAsia.
What is the history of the plane in question?
A statement issued by Airbus following the incident said that the A320-200 in question had clocked around 23,000 hours in the air across some 13,600 flights. It was delivered to AirAsia from the production line in October 2008, while the first A320-200 came into service in 1988. The airline said in a statement that the captain had 20,537 flying hours, 6,100 of which were with AirAsia Indonesia on the Airbus A320. The statement said the first officer officer had a total of 2,275 flying hours with AirAsia Indonesia.
Are there any hopes of finding passengers alive?
Officials are working on the theory that the plane crashed into the sea. "Based on the coordinates that we know, the evaluation would be that any estimated crash position is in the sea, and that the hypothesis is the plane is at the bottom of the sea," said Indonesia's National Search and Rescue chief Henry Bambang Soelistyo at a news conference, according to the AP.
What efforts are being made to find the plane?
A large multinational air and sea effort is underway to locate AirAsia flight QZ8501. Indonesia has been assisted by Singapore, Malaysia and Australia. which between them have mobilized dozens of aircraft and ships to hunt for the vanished jet. Singapore donated two sets of underwater locator beacon detectors — which can help find an aircraft's black boxes — as well as two teams of specialists. It said late Monday that it also had offered a sonar system and a robotic remotely-operated vehicle.
How large of a search area are we looking at?
The Java Sea, the body of water surrounded by Indonesia's islands, is about 120,000 square miles in size, similar to the area of New Mexico. However, knowing the point where the plane lost contact "narrows the search considerably," according to former NTSB board member Kitty Higgins. She told NBC News there is "good radar information in terms of where [and] when they lost sight of the plane on radar."
Is this anything like what happened to Malaysia Airlines flight MH370?
Officials and experts have been quick to throw cold water on comparisons between the AirAsia flight and Malaysia Airlines MH370, which disappeared on March 8 without a trace. Australian Prime Minister Tony Abbott told Sydney's Radio 2GB that "it would be a big mistake" to look for similarities with what he said was "one of the great mysteries of our time."
And oceanographer Dr. Simon Boxall told NBC News that because the Java Sea is much shallower than the MH370 search area in the Indian Ocean — 130 feet compared with upward of 13,000 feet — the prospect of finding any wreckage would be far more likely. "It's relatively shallow water and it's close to land so they can use helicopters, rather than spending hours just getting to the search area," said Boxall, who is based at at the U.K.'s University of Southampton. "It's not going to be easy, but it is feasible within a relatively short amount of time."
NBC News' Marc Smith and The Associated Press contributed to this report.