How technology pinpointed plane

Hours after Malaysian Airlines Flight MH 370 vanished with 239 people on board, Inmarsat pulled together a team of engineers thousands of kilometres away at its London headquarters for a marathon data-crunching session to help find the jet.

The mission: piecing together the few signals picked up by an Inmarsat satellite to direct the search, which in the initial phase focused on the Boeing 777's flight path from Kuala Lumpur to Beijing.

After a week of study, data revealed two plausible, if surprising, trajectories - one north into central Asia and one south towards Antarctica.

The breakthrough was based on research using the so-called Doppler effect, named after 19th-century Austrian physicist Christian Doppler who explored how movement can alter a signal profile. After establishing a broad flight path, the Inmarsat engineers hunkered down to pinpoint a possible crash site.

"They worked together for six or seven days straight," said Inmarsat spokesman Chris McLaughlin. The international team unwound at the in-house gym or fetched pizzas for breaks.

"What we discovered was that the northern projected path had no correlating pings appear on it, while for the southern projected path, we had, frankly, an absolute correlation. The plotted positions, the plotted lines all matched each other."

The teams, meeting in the glass-coated Inmarsat headquarters that border London's financial district, compared equivalent data from flights of other Boeing 777 jets in and out of the area to see where the Doppler effect would result in a pattern that matched the data from Flight MH370.

Inmarsat was set up in 1979 as an intergovernmental organisation to provide satellite communications for ships. It operates three constellations of 10 satellites in geostationary orbit 35786km above the Earth.

The team's breakthrough came at the weekend, McLaughlin said by phone.

Malaysian acting Transport Minister Hishammuddin Hussein said yesterday: "The new analysis was convincing enough for the AAIB [UK Air Accidents Investigation Branch] to brief the prime minister [Nijab Razak] that the aircraft flew in the southern corridor.

"This type of analysis has never been done in an investigation."