Relatives received the news they had been dreading (Image: Gof Chai Hin/AFP/Getty Images)

The Boeing 777 airliner that has been missing for more than two weeks crashed into the southern Indian Ocean, killing all 239 passengers and crew, according to a fresh analysis of the satellite data broadcast by the stricken Malaysia Airlines plane.

The news that relatives had dreaded came in an announcement by Malaysia’s prime minister Najib Razak, who said an analysis by the UK’s Air Accident Investigation Branch (AAIB) and the London-based satellite services provider Inmarsat was of a type never before performed on air incident data. But he is confident in its conclusions.

“It is therefore with deep sadness and regret that I must inform you that, according to this new data, flight MH370 ended in the southern Indian Ocean, west of Perth. This is a remote location far from any landing sites,” Razak said.


In a message to relatives, Malaysia Airlines said: “We have to assume beyond any reasonable doubt that MH370 has been lost and none of those on board survived.”

Vanished from radar

The plane took off from Kuala Lumpur for Beijing on 8 March. Less than an hour later, its radar transponder was disabled as it headed out over the South China Sea towards Vietnam, and the plane disappeared from radar. Its flight path after that was unclear and search efforts were launched in the South China Sea and Indian Ocean, where land-based radar had suggested it may have headed.

Many types of aircraft transmit technical data about things like engine health to the airline. Although, in this case, the airline did not subscribe to an Inmarsat service offering satellite transmission of that data, the Boeing 777 had an Inmarsat satellite transceiver fitted that still pinged an hourly data-free signal to an Inmarsat satellite.

On 15 March those signals were used to calculate how far the plane was from a geostationary satellite above the Indian Ocean. That led to the calculation that the plane was flying in either a broad northern corridor towards Kazakhstan, or a southern one headed deep into the open reaches of the Indian Ocean.

Satellite sighting

None of the nations on the northern track spotted the plane on radar, so most search efforts this week were concentrated on the empty southern corridor. And in recent days French, Australian and Chinese satellites spotted potential aircraft debris on the ocean surface. Today, both Chinese and Australian aircraft spotted debris on the ocean surface, too. None has yet been identified as being aircraft-related, however.

It is now clear that Inmarsat believed other details hidden in the pinged signal gave away the plane’s flight path – and its probable crash point – rather than merely its distance either side of the geostationary satellite. But to calculate that path it needed a methodology not used in aircraft tracking before, one that had to be peer reviewed for accuracy by a so-far unnamed rival satellite company, as well as by Boeing.

The method uses the physics of the Doppler effect. It is this effect that makes an ambulance siren go up in pitch as it approaches you and then lower as it passes and travels away. The same happens to radio waves as they are compressed and expanded by a moving source. It meant that the recorded frequency of the jet’s pings changed as it approached or moved away from the geostationary satellite. After comparing these changes with those from previous 777 flights in the region, Inmarsat is now certain the plane took the southerly route and flew at steady altitude until it ran out of fuel 2000 kilometres west of Perth, Australia.

“Previous flights gave us the pattern and that pattern – flying to the south – is virtually what we got. It is a very good fit,” Chris Mclaughlin, vice-president of Inmarsat, told Sky News.

Patient approach

Meanwhile, the US Navy is readying for an underwater search. It is sending a ship-towed device to its fleet in the Indian Ocean – one that can listen out for the ultrasonic signal from the downed aircraft’s flight recorders. Called the Towed Pinger Locator System the device can detect signals through 6000 metres of seawater – the Indian Ocean averages 4000 metres deep. But the cockpit voice and flight data recorders only have enough battery to broadcast a signal for 30 days after immersion, so time is getting tight.

In addition, it is not always easy to find deeply submerged devices, says John Powis, a former commanding officer of the British navy submarines HMS Unseen, HMS Resolution and HMS Victorious. “The range at which a ping can be heard depends on many environmental factors like background noise, changes of water density that cause ping refraction and shielding by seabed features including the wreckage itself,” he warns.

“Now it is confirmed that the aircraft went down in the ocean, a painstaking and patient approach is needed to try to establish the cause of this tragic incident,” says Jim McAuslan, general secretary of the British Airline Pilots Association.

“This approach will take time but lead to the detailed facts, which will enable pilots to push for any improvements to make every single flight a safe one and stop this type of event happening in future,” he says.

Clarification: Since this story was published on 24 March 2014, more information about how Inmarsat calculated the flight’s path has emerged. The article has been changed to reflect this.