How old technology helped find flight path
Print Edition
INMARSAT, a British satellite telecommunications company, used a wave phenomenon discovered in the 19th century to analyze ‘pings’ it picked up from Malaysia Airlines flight MH370 and determine its final destination.
The findings led Malaysian Prime Minister Najib Razak to conclude on Monday that the Boeing 777, which disappeared more than two weeks ago, crashed in the southern Indian Ocean, killing all 239 people on board.
The pings, automatically transmitted every hour from the aircraft after the rest of its communications systems had stopped, indicated it continued flying for several hours after it disappeared from its flight path from Kuala Lumpur to Beijing.
From the time the signals took to reach the satellite and the angle of elevation, Inmarsat was able to provide two arcs, one north and one south, that the aircraft could have taken.
Inmarsat’s scientists then analyzed the faint pings using a technique based on the Doppler effect, which describes how a wave changes frequency relative to the movement of an observer, in this case the satellite, a spokesman said.
The Doppler effect is why the sound of a police car siren changes as it approaches and then overtakes an observer.
Britain’s Air Accidents Investigation Branch was also involved in the analysis.
“We then took the data we had from the aircraft and plotted it against the two tracks, and it came out as following the southern track,” said Jonathan Sinnatt, head of corporate communications at Inmarsat.
The company then compared its theoretical flight path with data received from Boeing 777s that it knew had flown the same route, he said, and it matched exactly.
The findings were passed to another satellite company to check, he said, before being released to investigators.
The paucity of data — only faint pings received by a single satellite every hour or so — meant techniques like triangulation using a number of satellites or GPS could not be used to determine the aircraft’s flight path.
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