It has been lauded as a top scientific achievement but the sadness to relatives of the 239 passengers and crew of the missing Malaysian Airlines MH370 flight that resulted from their work will not be lost on engineers and scientists working at the mobile satellite communications firm Inmarsat. For they have now conclusively proven that the missing Malaysian Boeing 777 jet airliner was almost certainly lost in the Southern Indian Ocean. The Malaysian government has now formally accepted that this is so and has informed the relatives of those aboard the flight.
Inmarsat had originally revealed that it had been receiving and hourly “handshake” from carrier wave signal emitted by Malaysian Airlines MH370 flight via the Inmarsat 3F-1 satellite for hours after the aeroplane went missing. The firm’s original analysis using the timing of the signals concluded that the aircraft was in a track that arched across the Indian Ocean, North West or South West of Malaysia. By further analysing the Doppler effect’s shift of the L-band signal (Doppler shift is the apparent compression or expansion of the wavelength caused by transmissions from a moving object), and comparing it to the transmissions of other aircraft moving in the vicinity, researchers at the firm in conjunction with engineers at Boeing and experts at the UK Air Accident Investigations Branch, have found that the aircraft was heading on the southerly track and was at the limit of its fuel endurance as it transmitted its last signals west of Perth, Australia.
A more detailed explanation is at: http://www.spaceflightnow.com/news/n1403/24mh370/#.UzKgvs-PMiQ
As a result of the international concern that a modern jet airliner could go untracked for weeks, moves are being made to have continually transmitting tracked positions of aircraft using the Iridium-satellite-tracked ADS-B system for remote and oceanic regions.