LONDON, March 24 (Xinhua) -- A remarkable piece of high-tech data detective work has provided what looks to be the missing clue to the tragic fate of missing Malaysia Airlines Flight MH370, an expert said Monday.
Malaysian Prime Minister Najib Razak earlier on Monday said that information provided by British satellite company Inmarsat and the British government's Air Accidents Investigation Branch (AAIB) confirmed that MH370 had flown to a remote part of the Indian Ocean where the flight ended.
David Stupples, professor of electrical and electronic engineering at City University in London, told Xinhua Monday evening, "I think Inmarsat has moved incredibly quickly. If you put this out to a research organisation they would probably have taken three to six months to come up with some research like that. Inmarsat has achieved this in a few days."
Inmarsat had come up with a theory to apply to the data it had collected from MH370 during the flight, and had then tested the results on aircraft in flight.
Stupples explained that the satellite systems on board the aircraft were not switched off, so would have been registering with the Inmarsat satellite.
Stupples said the aircraft was "electronically silent", apart from this registration with the Inmarsat satellite, which was working on its uplink.
"This registration occurs once every hour, and the transponder on the aircraft will say 'I'm still here', and the satellite will come back and say 'Gotcha'," said Stupples.
Stupples said the satellite was in a geo-stationary orbit, at 37,000 km above the equator and a signal from the aircraft to the satellite would take about 0.12 of a second; this would take longer to arrive the further north or south the plane was of a center point on a cone of possible positions.
Stupples explained, "Because of this they knew it was on a corridor that was either going north or south. Now they knew it was not going north because none of the radars in Thailand or Burma or above there had registered an unidentified aircraft in their airspace."
He added, "So they said it went south; what Inmarsat has done is take the signals received from the aircraft and looked at the frequency change. If you stand on an race track with a race car coming towards you, you notice there is a sound difference as it comes towards you and then it drops away."
Stupples said this was the Doppler Effect, and the principle could be applied to satellite signals.
"So, what they did here was to analyse the signals received from the aircraft, then calculate that the aircraft was moving south at a certain velocity," he said.
Stupples said Inmarsat knew MH370 had made seven pings, one every hour, and that it had been travelling for seven hours and that is approximately the fuel that the aircraft had on it.
Stupples continued, "They tested this on a number of aircraft flying around to make certain that this principle worked."
"I think it can be used in the future. We are all very sad at the tragic loss, so we hope this kind of technology will never be used again because hopefully we won't end up with another missing aircraft as we have here," he added.