Malaysia Airlines Flight 370 (MH370/MAS370)

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.^[8][9][10] 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.

Theories

Rob Brotherton, a lecturer in psychology at Goldsmiths, University of London, wrote that conspiracy theories emerge immediately after any catastrophe occurs and conclusive information about why they do so remains unavailable. Andrew Leonard wrote that conspiracy theorists were bolstered by the revelation of new satellite data two weeks after the flight disappeared that had been hidden from the public.
Other factors involve the lack of a distress signal from the plane According to Barbara Demick of the Los Angeles Times, critics of the Malaysian government's statements also found support in the Joint Agency Coordination Centre's announcement on 29 May 2014 that the plane was not in the search area authorities had been combing since April 2014.

Conspiracy-focused internet sites claim that the official statement that the plane crashed into the Indian Ocean makes no sense. They note that a Boeing 777 does not have the structural integrity to survive crashing into the ocean, and that it would be comparable to hitting a cement wall at terminal velocity. If Flight 370 hit the ocean, they say, it would have been broken into tens of thousands of pieces, many of which float on water (such as the seat cushions) and would be seen washing up on regional shores or easily spotted by search teams
Harvard professor Cass Sunstein noted that the conflicting information initially released by the Malaysian government explains the interest in alternative theories. Sunstein, who has written on the topic in an interview with the Wall Street Journal on 20 March 2014, argued that conspiracy theories in general often are borne out of horrific and disastrous situations, because such events make people angry, fearful and looking for a "target"

Hijacking

 The possibility of a simple hijacking has been brought up by various news outlets, including ABC News and the Los Angeles Times.Speculation has mounted about the possibility that hijackers took the plane to a remote island, although no group has stepped forward to confirm that it was them; however, unofficial researchers have identified more than 600 possible runways at which the plane was capable of landing. No confirmation has been received from Malaysian officials

Electronic hijacking

 Electronic hijacking uses systems and programming already factory installed within the B777 flight management system. This is different from hacking or cyber-attack in that it requires access to the B777's security system through access purposefully programmed into the software. Notable proponents of this theory include former Malaysian prime minister Mahathir Mohamad. He said: "Clearly Boeing and certain agencies have the capacity to take over uninterruptible control of commercial airliners of which MH370 B777 is one". In this statement he was referring to off-board hijackers with access to MH370's Flight Management System via the 2003 patented Uninterruptible Autopilot.
And so the list goes on 
"Spoofed" satellite data, Terrorist attack, North Korea,  Acquisition of Freescale staff, Diego Garcia, Shoot-down theory etc