MH370: What We Know And What We Don't

Kuala Lumpur: Boeing 777 debris found on the island of Reunion appears to prove that missing Malaysia Airlines Flight 370 crashed in the Indian Ocean, but the cause of the disaster remains unknown.

Below are key things we know, and don't know, in the mysterious case of MH370.

What we know

-- We know MH370 took off from Kuala Lumpur with 227 passengers and 12 crew at 12:41 am on March 8 last year, climbing out over the South China Sea on a clear night, bound for Beijing.

-- We know the plane was piloted by Zaharie Ahmad Shah, 53, a highly respected airman with 33 years of experience at the state flag carrier. Fariq Abdul Hamid, 27, was his co-pilot.

-- We know that just before MH370 was to pass into Vietnam's air-traffic control region, someone in the cockpit sent the final voice message back to Malaysian controllers: "Good night, Malaysian Three Seven Zero," at 1:19am.

-- We know that around 1:30 am, tracking systems such as the jet's transponder were shut off, yet the plane appeared on military radar until 2:15 am as it turned back over Malaysia and flew out to the Indian Ocean.

-- We know that a wing part found on Reunion has been confirmed as from a Boeing 777, making it virtually certain that it is from MH370 as no other such plane is known to have crashed in the area.

-- We know that the 30-day beacon battery on MH370's flight data recorder was later discovered to have expired more than a year before take-off, raising questions over whether this contributed to the inability of a multi-nation search to find an Indian Ocean crash site.

What we don't know

-- We still have no idea what caused the plane to divert since neither the cockpit crew nor the plane's monitoring systems gave any sign of trouble prior to that, and the weather was clear that night.

-- We don't know whether one of the cockpit crew was involved, considered by many experts to be the most likely explanation. Zaharie was a known supporter of Malaysia's opposition, and it was later found that Fariq had let passengers into the cockpit on an earlier flight, breaching safety rules. But investigators say nothing in either man's background suggests a desire to commit mass murder.

-- We don't know whether a hijack or terror attack was responsible, since there has never been a claim of responsibility by any group or individual.

-- We don't know why the plane's tracking systems were switched off and by whom, an act that Malaysia has said appeared to be "deliberate."

-- We still don't know exactly where MH370 went down, meaning we are no closer to recovering the aircraft's black box and analysing it for clues as to what caused its disappearance.