A Malaysia-led multinational investigation team has published what facts it knows about Malaysia Airlines flight MH370, the scheduled Kuala Lumpur-Beijing flight that disappeared without trace on 8 March 2014.

There are no conclusions about where it is or why it diverted from its flightplan.

The 587-page report, released by the minister of transport, summarises what is known about the missing Boeing 777-200 and its maintenance history. It also describes the flightpath it followed while it was in radar range, and what its track is likely to have been – based on satellite communications – beyond radar surveillance, until the time at which it would have run out of fuel.

If there are any reliable clues as to why the aircraft took the trajectory it did, they are to be found between the time the crew checked in for duty – 22:50 local time – and the time the aircraft could no longer be observed on radar, 02:22 local time the next day.

The deduction that the aircraft then turned south unseen is based on Inmarsat analysis of variations in satellite "handshake" exchanges with the aircraft – the only information available. But these were few, and the accuracy of any deductions drawn from them is not guaranteed. From the sparse information available, it seems probable that the search for the aircraft is being conducted in the best area, but there are no certainties.

After a normal departure from Kuala Lumpur to the northeast at 00:40 local time, climb to cruise went according to flightplan. At 01:19:26, Kuala Lumpur told MH370 to contact Ho Chi Minh air traffic control centre on frequency 120.9 MHz. After 4s, the voice of the captain, Zaharie Ahmad Shah, replied: "Goodnight, Malaysia 370" – but he did not read back the radio frequency, as he had done in a previous transmission. This was the last recorded radio transmission from MH370. Just over 1min later, its Mode S transponder code dropped off the radar display. This was 5s after the aircraft had passed through waypoint IGARI, on the boundary between the Kuala Lumpur and Ho Chi Minh flight information regions (FIR).

Slightly less than 9min later, Ho Chi Minh called Kuala Lumpur and asked where MH370 was, because the captain had not called the Vietnamese centre and the transponder return had been lost. Kuala Lumpur then contacted Malaysia Airlines' operations centre, Hong Kong ATC and Phnom Penh ATC in Cambodia, to solicit help in locating the aircraft.

Meanwhile, on military radar and Kota Bharu civil primary radar, the aircraft was seen to turn left near IGARI onto an almost reciprocal southwesterly track (231˚M), and was tracked close to the FIR boundary all the way over the Malay peninsula into the Malacca Strait, coasting out just south of Penang. There it turned northwest, intercepting airway N571. The 777 followed the airway until 10nm (18.5km) beyond waypoint MEKAR, where it was lost to all radar coverage over the Andaman Sea at 02:22:12. Following the diversion at IGARI, radar saw the aircraft's flight level vary from the cleared cruise of FL350 (35,000ft) to a maximum of 35,700ft and minimum 31,100ft, with groundspeed fluctuations also.

This dramatic diversion from the flight's planned route, combined with the flight-level fluctuations, would not be accounted for by a preprogrammed flight-management system taking over from an incapacitated crew. So if the diversion was deliberate, the question of motive arises, and the report looks into this issue.

"There were no behavioural signs of social isolation, change in habits or interest, self-neglect, drug or alcohol abuse of the captain, first officer and the cabin crew," the report says. "The CCTV recordings at KLIA [Kuala Lumpur International airport] on 7 March 2014 were evaluated to assess the behavioural pattern of the [pilots] from the time of arrival at KLIA until boarding time." These were compared with video of other departures by the same pilots, and the report says there were no apparent behavioural changes. Checks on both pilots' financial situation, insurance policies and health histories yielded no clues that anything was abnormal.

While the report provides facts, it does not attempt to draw conclusions. Unless the aircraft wreckage and its recorders are found, the causes of this extraordinary event will remain unknown.

Malaysia’s prime minister Najib Razak says the nation is committed to finding the lost aircraft, with its 227 passengers and 12 crew. "Together with our international partners, we have followed the little evidence that exists. Malaysia remains committed to the search, and is hopeful that MH370 will be found."

Source: FlightGlobal.com