How British satellite company Inmarsat tracked down MH370
The British company that provided vital information on MH370’s whereabouts explains its calculations
3:16PM GMT 24 Mar 2014
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The Malaysian government has concluded that, based on satellite data analysis from British company Inmarsat, Malaysian Airlines flight MH370 ended in the Indian Ocean, and no one on board survived.
In a press statement this afternoon, Prime Minister Najib Razak said that, using a type of analysis "never before used in an investigation of this sort", Inmarsat engineers have been able to establish that the plane's last position was in the middle of the Indian Ocean, west of Perth.
"This is a remote location, far from any possible landing sites. 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."
Inmarsat’s role in the search for Malaysian Airlines flight MH370 began immediately after the aircraft disappeared. Although the main aircraft communications addressing and reporting system (which would usually transmit the plane's position) was switched off, one of Inmarsat’s satellites continued to pick up a series of automated hourly 'pings' from a terminal on the plane, which would normally be used to synchronise timing information.
By analysing these pings, Inmarsat was able to establish that MH370 continued to fly for at least five hours after the aircraft left Malaysian airspace, and that it had flown along one of two 'corridors' – one arcing north and the other south. The plane was reportedly flying at a cruising height above 30,000 feet.
"We looked at the Doppler effect, which is the change in frequency due to the movement of a satellite in its orbit. What that then gave us was a predicted path for the northerly route and a predicted path the southerly route," explained Chris McLaughlin, senior vice president of external affairs at Inmarsat. "That’s never been done before; our engineers came up with it as a unique contribution."
This information was relayed to Malaysian officials by 12 March, but Malaysia's government did not publicly acknowledge it until 15 March, according to the Wall Street Journal. Malaysia began to redirect the search effort that day, to focus on the areas the information described. However, some officials involved with the probe warned that the lost days and wasted resources could impede the investigation.
Meanwhile, Inmarsat's engineers carried out further analysis of the pings and came up with a much more detailed Doppler effect model for the northern and southern paths. By comparing these models with the trajectory of other aircraft on similar routes, they were able to establish an "extraordinary matching" between Inmarsat's predicted path to the south and the readings from other planes on that route.
"By yesterday they were able to definitively say that the plane had undoubtedly taken the southern route," said McLaughlin.
These pings from the satellite – along with assumptions about the plane’s speed – helped Australia and the US National Transportation Safety Board to narrow down the search area to just 3 per cent of the southern corridor on 18 March.
"We worked out where the last ping was, and we knew that the plane must have run out of fuel before the next automated ping, but we didn't know what speed the aircraft was flying at – we assumed about 450 knots," said McLaughlin. "We can’t know when the fuel actually ran out, we can’t know whether the plane plunged or glided, and we can’t know whether the plane at the end of the time in the air was flying more slowly because it was on fumes."
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