“Almost inconceivable and certainly societally unacceptable in the modern aviation era” — that is how the mystery of MH370 is summed up by the final report into the search for the doomed aircraft.

On 8 March 2014, Malaysia Airlines flight MH370 disappeared on a routine flight from Kuala Lumpur to Beijing with 227 passengers and 12 crew.

Its last position to be identified by surveillance systems was at the northern tip of Sumatra, way off the course it should have flown.

Analysis of communication “pings” indicated that the plane flew for a further six hours before running out of fuel and crashing into the southern Indian Ocean.

“The aircraft was not configured for a ditching at the end-of-flight,” notes the report.

In April 2014, the Australian Transport Safety Bureau (ATSB) took control of the underwater search for the Boeing 777, extending up to 2,800km west of the coast of western Australia. Despite a massive international effort that lasted over two years, studying the sea floor up to 6km below the surface, the only traces of the aircraft to have turned up are fragments of wreckage washed up on the western shores of the Indian Ocean.

The ATSB’s final report into the fruitless search has now been published. It runs to 440 pages.

“The initial surface search and the subsequent underwater search for the missing aircraft have been the largest searches of their type in aviation history,” says the report.

In the largest hydrographic survey ever conducted, investigators mapped a total of 710,000 square kilometres of Indian Ocean sea floor: larger than the area of France.

Yet despite “the extraordinary efforts of hundreds of people involved in the search from around the world”, the fate of MH370 aircraft remains a mystery.

In the hardest-hitting passage of the report, the ATSB says: “Whether or not the loss of MH370 was the result of deliberate action by one or more individuals, or the result of a series of unforeseen events or technical failures, it is almost inconceivable and certainly societally unacceptable in this modern aviation age with 10 million passengers boarding commercial aircraft every day, for a large commercial aircraft to be lost and for the families of those on board not to know with certainty what became of the aircraft nor those on board.”

After the search was abandoned, a different Australian agency claimed it could pinpoint the location for MH370 “with unprecedented precision and certainty”.

But plans to begin a new search have yet to be announced.

The report concludes: “The ATSB expresses our deepest sympathies to the families of the passengers and crew on board MH370.