One little piece of a wing has been found, along with perhaps a part of a tail section. Beyond that, the fate of Malaysia Airlines Flight MH370 remains an aviation mystery, two years after the Boeing 777 went missing on its way to Beijing.
Many questions remain after the plane's disappearance in the early hours of March 8, 2014.
With all the satellite surveillance and tracking technology available today, how could a jetliner simply vanish? And why hasn't it been found, even after a wing flap was discovered washed up on a remote island in the Indian Ocean?
- Flight MH370 debris could reach Mozambique, officials say
- Analysis suggests plane located within official search area
- France confirms part found on Réunion Island is from missing plane
Here's a look at what is known about Malaysia Airlines Flight MH370, as well as some theories about what might have happened.
What we know
The plane took off from Kuala Lumpur at 12:41 a.m. local time on March 8, 2014, carrying 239 people. The original destination was Beijing, with arrival scheduled for nearly six hours later, at 6:30 a.m. local time.
Last ACARS message
Malaysian authorities say that at 1:07 a.m., the plane sent its last message via the Aircraft Communications Addressing and Reporting System (ACARS), an automated system that relays performance data about each flight (including turbulence, fuel usage and any maintenance concerns) to the airline.
Sign-off from the cockpit
Malaysian authorities reported having audio of either the pilot, Capt. Zaharie Ahmad Shah, or his first officer, Fariq Abdul Hamid, saying, "All right, good night" in a transmission to air traffic control.
The Malaysian government later changed its account of the final voice transmission, saying the last words received by controllers at Kuala Lumpur's international airport at 1:19 a.m. local time on March 8 were "Good night Malaysian three-seven-zero."
After 40 minutes of flight time, at about 1:21 a.m., the plane's transponder stopped transmitting and ground control lost contact with the aircraft.
Last confirmed position
At 2:14 a.m., just over one and a half hours after the plane departed Kuala Lumpur, Malaysian military radar identified the plane in the northern part of the Strait of Malacca.
Last satellite signal
ACARS continued to transmit "pings" to satellites for four to five hours, a senior U.S. official told CNN.
The last signal was picked up by a satellite at 8:11 a.m., which suggests MH370 had deviated from its northward course to Beijing and was somewhere in a geographical radius spanning from Kazakhstan to the Indian Ocean west of Australia.
Search efforts have been adjusted several times, but have focused on a 120,000-square-kilometre expanse of remote waters west of Australia. The plane is believed to have crashed in that area after flying on autopilot for hours before running out of fuel. In December 2015, the Australian-led search efforts were refocused on the southern reaches of the search zone, based on a new analysis of the flight's last hours.
In September 2015, French investigators formally identified a washed-up piece of airplane debris found three months earlier on a remote island in the Indian Ocean as part of Flight 370. The wing part, called a flaperon, was found on Réunion Island and later identified using maintenance records and a serial number.
Debris that washed up in Mozambique in late February 2016 was tentatively identified as being from a Boeing 777. Officials say debris from Flight 370 could reach Mozambique, a coastal country in southeastern Africa about 6,000 kilometres from the area where the plane is believed to have crashed.
4 theories about flight MH370
The mysterious disappearance of MH370 sparked speculation from experts and amateurs alike. Here are some of the theories.
Passengers and crew suffocated
On June 26, 2014, the Australian Transport Safety Board released a 55-page report that concluded the passengers and crew suffocated on-board, and that the plane eventually fell into the ocean.
The report said investigators came to this conclusion by comparing the conditions on the flight with previous disasters, but offered no evidence from within the aircraft.
The investigators noted, among other things, the lack of communications and the steady flight path.
"Given these observations, the final stages of the unresponsive crew/hypoxia event type appeared to best fit the available evidence for the final period of MH370's flight when it was heading in a generally southerly direction," the ATSB report said.
When flight MH370 went missing, some observers suggested it might have been hijacked by extremists with a political agenda.
After satellite data showed that MH370 had made a sharp westward deviation from its intended destination, some took this as proof of a mid-air takeover.
No extremist group has claimed responsibility for such an act.
Flight MH370's seemingly deliberate change of course also spurred theories that it may be a case of sabotage.
On March 14, 2014, a senior Malaysian police official said, "What we can say is we are looking at sabotage, with hijacking still on the cards."
Chris Goodfellow, a Canadian pilot with 20 years' experience, posited a more straightforward theory that was reprinted in Wired magazine.
Goodfellow wrote that "there most likely was an electrical fire" that forced the pilot to "make an immediate turn to the closest, safest airport."
Based on the satellite data about where Flight MH370 was heading after it turned off its course to Beijing, Goodfellow determined that the pilot's intended destination was a 4,000-metre airstrip on Pulau Langkawi, an island in northern Malaysia.