Malaysia Airlines Flight 370 (MH370/MAS370) was a scheduled international passenger flight that disappeared on 8 March 2014, while flying from Kuala Lumpur International Airport near Kuala Lumpur, Malaysia, to Beijing Capital International Airport in Beijing, China. The flight last made voice contact with air traffic control at 01:19 MYT, 8 March (17:19 UTC, 7 March) when it was over the South China Sea, less than an hour after takeoff. The aircraft disappeared from air traffic controllers' radar screens at 01:22 MYT. Malaysian military radar continued to track the aircraft as it deviated from its planned flight path and crossed the Malay Peninsula. It left the range of Malaysian military radar at 02:22 while over the Andaman Sea, 200 nautical miles (370 km) northwest of Penang in northwestern Malaysia. The aircraft, a Boeing 777-200ER, was carrying 12 Malaysian crew members and 227 passengers from 15 nations.

A multinational search effort began in the Gulf of Thailand and the South China Sea, where the flight's signal was lost on secondary surveillance radar, and was soon extended to the Strait of Malacca and Andaman Sea. Analysis of satellite communications between the aircraft and Inmarsat's satellite communications network concluded that the flight continued until at least 08:19 and flew south into the southern Indian Ocean, although the precise location cannot be determined. Australia took charge of the search effort on 17 March, when the search shifted to the southern Indian Ocean. On 24 March 2014, the Malaysian government noted that the final location determined by the satellite communication is far from any possible landing sites, and concluded that "flight MH370 ended in the southern Indian Ocean." The current phase of the search is a comprehensive search of the seafloor about 1,800 kilometres (970 nmi) southwest of Perth, Western Australia, which began in October 2014. Despite the largest and most expensive search in aviation history, nothing was found of the aircraft until 29 July 2015, when a piece of marine debris, later confirmed to be a flaperon from Flight 370, was found on Réunion Island. The bulk of the aircraft has still not been located, prompting many theories about its disappearance.

Malaysia established the Joint Investigation Team (JIT) to investigate the incident, working with foreign aviation authorities and experts. Neither the crew nor the aircraft's communication systems relayed a distress signal, indications of bad weather, or technical problems before the aircraft vanished. Two passengers travelling on stolen passports were initially suspected in the disappearance, but they were later determined to be asylum seekers and it has been ruled out that they were terrorists. Malaysian police have identified the Captain as the prime suspect if human intervention was the cause of the disappearance, after clearing all other passengers of any suspicious motives. Power was lost to the aircraft's satellite data unit (SDU) at some point between 01:07 and 02:03; the SDU logged onto Inmarsat's satellite communication network at 02:25—three minutes after the aircraft left the range of radar. Based on analysis of the satellite communications, the aircraft turned south after passing north of Sumatra and flew for five hours with little deviation in its track, ending when fuel was exhausted.

If the presumed loss of all on board is confirmed, Flight 370 would be the second deadliest incident involving a Boeing 777 and the second deadliest incident in Malaysia Airlines' history, behind Flight 17. Malaysia Airlines was struggling financially, a problem which was exacerbated by a decline in ticket sales after Flight 370 disappeared and before the crash of Flight 17; the airline was renationalised by the end of 2014. The Malaysian government received significant criticism, especially from China, for failing to disclose information in a timely manner during the early weeks of the search. Flight 370's disappearance brought to the public's attention the limits of aircraft tracking and flight recorders, including several issues raised four years earlier—but never mandated—following the loss of Air France Flight 447. A task force set up by the International Air Transport Association, with the support of the International Civil Aviation Organization, proposed a new standard that commercial aircraft must report their position every 15 minutes by December 2015. The Malaysian Ministry of Transport issued an interim report on 8 March 2015.