Doppler effect analysis helped narrow Malaysian jetliner search

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Doppler effect analysis helped narrow Malaysian jetliner search
Relatives of Chinese passengers from the missing Malaysia Airlines flight MH370 offer prayers at Thean Hou Temple in Kuala Lumpur on March 1, 2015. The visit to the temple comes nearly a year after Malaysian Airlines MH370 went missing en route from Kuala Lumpur to Beijing with 239 people on board in March 2014. AFP PHOTO / MOHD RASFAN (Photo credit should read MOHD RASFAN/AFP/Getty Images)
A relative of one of the Chinese passengers from the missing Malaysia Airlines flight MH370 cries before offering prayers at Thean Hou Temple in Kuala Lumpur on March 1, 2015. The visit to the temple comes nearly a year after Malaysian Airlines MH370 went missing en route from Kuala Lumpur to Beijing with 239 people on board in March 2014. AFP PHOTO / MOHD RASFAN (Photo credit should read MOHD RASFAN/AFP/Getty Images)
A Relative of Chinese passengers from the missing Malaysia Airlines flight MH370 cries as he gathers outside Malaysian Prime Minister Najib Razak's office in Putrajaya on February 18, 2015. Chinese relatives of MH370 passengers gathered outside the Malaysian prime minister's office to demand his government rescind its declaration that all on board the plane were presumed dead. AFP PHOTO/ MANAN VATSYAYANA (Photo credit should read MANAN VATSYAYANA/AFP/Getty Images)
Relatives of Chinese passengers from the missing Malaysia Airlines flight MH370 offer prayers at Thean Hou Temple in Kuala Lumpur on March 1, 2015. The visit to the temple comes nearly a year after Malaysian Airlines MH370 went missing en route from Kuala Lumpur to Beijing with 239 people on board in March 2014. AFP PHOTO / MOHD RASFAN (Photo credit should read MOHD RASFAN/AFP/Getty Images)
Relatives of Chinese passengers from the missing Malaysia Airlines flight MH370, cries during a protest outside the Malaysia Airlines office in Subang on the outskirts of Kuala Lumpur on February 12, 2015. Chinese relatives of passengers on missing flight MH370 protested outside the Malaysian Airlines office demanding Malaysia withdraw the statement that all the passengers are dead. About 15 people gathered outside the gates wearing white caps and red t-shirts with words: 'Pray for MH370.' AFP PHOTO / MANAN VATSYAYANA (Photo credit should read MANAN VATSYAYANA/AFP/Getty Images)
A relative of one of the Chinese passengers from the missing Malaysia Airlines flight MH370 cries before offering prayers at Thean Hou Temple in Kuala Lumpur on March 1, 2015. The visit to the temple comes nearly a year after Malaysian Airlines MH370 went missing en route from Kuala Lumpur to Beijing with 239 people on board in March 2014. AFP PHOTO / MOHD RASFAN (Photo credit should read MOHD RASFAN/AFP/Getty Images)
The Malaysian government says the plane is believed to have went down in a remote area of the Indian Ocean and everyone on board was killed.
Malaysian activists hold banners during a protest accusing US news channels of unprofessional reporting on missing Malaysia Airlines flight MH370, outside the US Embassy in Kuala Lumpur on April 3, 2014. Malaysian Prime Minister Najib Razak vowed on April 3 'we will not rest' until the fate of Flight MH370 is known, as Australia called it 'the most difficult search in human history'. AFP PHOTO / MANAN VATSYAYANA (Photo credit should read MANAN VATSYAYANA/AFP/Getty Images)
Malaysian activists hold banners during a protest accusing US news channels of unprofessional reporting on missing Malaysia Airlines flight MH370, outside the US Embassy in Kuala Lumpur on April 3, 2014. Malaysian Prime Minister Najib Razak vowed on April 3 'we will not rest' until the fate of Flight MH370 is known, as Australia called it 'the most difficult search in human history'. AFP PHOTO / MANAN VATSYAYANA (Photo credit should read MANAN VATSYAYANA/AFP/Getty Images)
PERTH, AUSTRALIA - APRIL 04: Chief Coordinator of the Joint Agency Coordination Centre, Air Chief Marshal Angus Houston (Ret'd) addresses the media at press conference at Dumas House on April 4, 2014 in Perth, Australia. Fourteen planes and nine ships resumed in the search for missing Malaysia Airlines flight MH370 in the Indian Ocean off the coast of Western Australia today. The airliner disappeared on March 8 with 239 passengers and crew on board and is suspected to have crashed into the southern Indian Ocean. (Photo by Paul Kane/Getty Images)
Malaysian activists hold banners during a protest accusing US news channels of unprofessional reporting on missing Malaysia Airlines flight MH370, outside the US Embassy in Kuala Lumpur on April 3, 2014. Malaysian Prime Minister Najib Razak vowed on April 3 'we will not rest' until the fate of Flight MH370 is known, as Australia called it 'the most difficult search in human history'. AFP PHOTO / MANAN VATSYAYANA (Photo credit should read MANAN VATSYAYANA/AFP/Getty Images)
Communications specialist Hidetaka Sato, on a Japan Coast Guard Gulfstream aircraft, looks out of a window searching for missing Malaysia Airlines flight MH370 over the southern Indian Ocean on April 1, 2014. Malaysia revealed the full radio communications with the pilots of its missing flight on April 1, but the routine exchanges shed no light on the mystery as an Indian Ocean search for wreckage bore on with no end in sight. AFP PHOTO / POOL / Rob GRIFFITH (Photo credit should read ROB GRIFFITH/AFP/Getty Images)
Page 1 of the full transcript of communications between flight MH370 and Kuala Lumpur Air Traffic Control released by the Malaysian defense minister on Tuesday, April 1, 2014.
Page 2 of the full transcript of communications between flight MH370 and Kuala Lumpur Air Traffic Control released by the Malaysian defense minister on Tuesday, April 1, 2014.
Malaysian officials show Chinese relatives of passengers on the missing Malaysia Airlines flight MH370 the new search area at the Metro Park Hotel in Beijing on March 28, 2014. Relatives of the Chinese passengers aboard missing Malaysia Airlines flight MH370 have demanded China mount its own inquiry into the disappearance, a letter shows. The document, sent to Beijing's special envoy in Kuala Lumpur, denounced Malaysia's handling of the search and asked the Chinese government to set up its own 'investigation office'. AFP PHOTO/Mark RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images)

Photo posted to Twitter by China's CCTVNEWS of an object spotted and photographed in the new Flight MH370 search area on Friday, March 28, 2014.

The tweet read:

Picture: suspicious object spotted by New Zealand military plane on Friday. #MH370 http://t.co/KWCt1zrv2k

INDIAN OCEAN - This handout Satellite image made available by the AMSA (Australian Maritime Safety Authority) shows a map of the new search area in the Indian Ocean for missing Malaysian Airlines Flight MH370 on March 28, 2014. The revised search area, 680 miles to the north of previous searches, comes after a new radar analysis suggests the jetliner may have run out of fuel sooner than first believed.
Messages from schoolchildren to Chinese relatives of passengers on the missing Malaysia Airlines flight MH370 at the Metro Park Hotel in Beijing on March 28, 2014. Relatives of the Chinese passengers aboard missing Malaysia Airlines flight MH370 have demanded China mount its own inquiry into the disappearance, a letter shows. The document, sent to Beijing's special envoy in Kuala Lumpur, denounced Malaysia's handling of the search and asked the Chinese government to set up its own 'investigation office'. AFP PHOTO/Mark RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images)
Malaysian Minister of Defence and Acting Transport Minister Hishammuddin Hussein shows pictures of possible debris during his statement on the missing Malaysia Airlines flight MH370 at the Putra World Trade Center (PWTC) in Kuala Lumpur on March 26, 2014. Malaysia drew criticism on March 25 for its announcement that the missing passenger jet had been lost at sea, even before any wreckage was found. AFP PHOTO / MOHD RASFAN (Photo credit should read MOHD RASFAN/AFP/Getty Images)
A Japan Maritime Self-Defense Force AP-3C Orion arrives back at RAAF Base Peace at Bullsbrook, some 35 kms north of Perth after continuing the search for debris or wreckage of the missing Malaysia Airlines Flight MH370 in the Indian Ocean, on March 26, 2014. Six countries have joined the search for the missing plane believed to have crashed in the southern Indian Ocean. AFP PHOTO/POOL/ROB GRIFFITH (Photo credit should read ROB GRIFFITH/AFP/Getty Images)
A Malaysia Airlines plane (below) prepares to go onto the runway and pass by a stationary Chinese Ilyushin 76 aircraft (top) at Perth International Airport on March 25, 2014. Wild weather halted the search on March 25 for wreckage from the Malaysia Airlines jet that crashed into the Indian Ocean, frustrating attempts to determine why it veered off course and bring closure to grieving relatives. AFP PHOTO / POOL / Greg WOOD (Photo credit should read GREG WOOD/AFP/Getty Images)
Updated search map in hunt for missing Flight MH370 on Monday, March 24, 2014.
Satellite image shared with Australian officials by China in the search for Flight MH370 on Saturday, March 22, 2014.
A Chinese woman takes a photo of a message board set up by relatives of passengers from the missing Malaysia Airlines flight MH370 at Metro Park Lido Hotel in Beijing on March 24, 2014. Ships and planes from several nations swarmed over the southern Indian Ocean on March 24 as mounting evidence of floating debris energised the search for Malaysia's missing passenger jet. AFP PHOTO/GOH CHAI HIN (Photo credit should read GOH CHAI HIN/AFP/Getty Images)
Australia's deputy prime minister said the search for missing Malaysia Airlines Flight MH370 cannot go on forever, and discussions are already under way between Australia, China and Malaysia as to whether to call off the hunt within weeks. No trace has been found of the Boeing 777 aircraft, which disappeared a year ago this week carrying 239 passengers and crew, in what has become one of the greatest mysteries in aviation history.
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By JUSTIN PRITCHARD and KELVIN CHAN

HONG KONG (AP) - Investigators are closer to solving an international aviation mystery thanks to a British communications satellite and classroom physics.

An analysis of faint signals sent from Malaysia Airlines Flight 370 to an Inmarsat satellite led officials to conclude the plane crashed in a remote area of the southern Indian Ocean. More precise information about the plane's position when it sent the last signals is helping authorities refine the search being undertaken by planes and ships in seas 2,500 kilometers (1,550 miles) southwest of Perth, Australia. Investigators had little to examine otherwise because other communications were lost early in the flight March 8.

THE TIMING

Even with other communications shut down, the plane sent an automatic signal - a "ping" or a "handshake" - every hour to an Inmarsat satellite. Flight 370 completed six pings, and the time each took to be sent by the plane and received by the satellite showed the plane's range from the satellite, according to the U.K. Air Accidents Investigation Branch. This initial analysis showed the last ping came from a position along one of two vast arcs north and south from the Malaysian Peninsula.

DOPPLER EFFECT

Think of a horn being honked in a passing car. To an observer, the sound is high pitched as the car approaches and is lower after the car passes. On approach, each successive sound wave is sent from a slightly closer position to the observer. The sound waves get compressed, resulting in a higher frequency. The opposite happens as the car moves away. It's called the Doppler effect for Austrian physicist Christian Doppler, who put forward the theory in 1842.

The same effect applies to the pings, which would arrive to the satellite at a higher frequency if the plane was moving toward the satellite and decrease in frequency when moving away.

For the analysis that led to Monday's conclusion the plane had crashed, Inmarsat studied the satellite communications made while the plane was on the ground at Kuala Lumpur airport and early in its flight.

It considered aircraft performance, the satellite's fixed location and other known factors. By knowing how the Doppler effect would apply to the satellite communications, Inmarsat could calculate the possible positions, direction of travel and speed of the plane.

The company then compared its predictions to six other Boeing 777 aircraft that flew the same day, and found good agreement, according to Malaysian Defense Minister Hishammuddin Hussein. Inmarsat did not respond to repeated requests for comment from The Associated Press.

"By analyzing that you can determine speed and direction," said Joseph Bermudez Jr., chief analytics officer and co-founder of AllSource Analysis, a commercial satellite intelligence firm. And by determining the area from which the last signal was sent, then estimating fuel left, it "could give you an approximate area of where the aircraft impacted."

MORE ANALYSIS

Inmarsat sent its data to investigators days after the plane went missing. But it continued to run its own analysis to see if it could wring out any more clues.

The company's engineers were dealing with a "totally new area," Chris McLaughlin, senior vice president of external affairs at Inmarsat, told the BBC. "This really was a bit of a shot in the dark." However, the latest information could only go so far in pinpointing the jet's location.

"We can't help you with any closer data," he said.

Gregory D. Durgin, a professor who teaches satellite communications at the Georgia Institute of Technology, said that because Inmarsat was using a different kind of satellite in a novel way, he expects it would locate the last ping from the Malaysia Airlines lane within "around 100 miles (161 kilometers) of precision."

THE COMPANY

Inmarsat Plc started out in 1979 as an intergovernmental organization with the aim of helping ships communicate while at sea. It became a private company in 1999 and listed its shares in London in 2005. Customers now include governments, airlines, broadcast media, oil and gas companies, aid agencies as well as merchant shipping. They use hand-held satellite phones, laptop size Internet devices and antennas linked to the company's 10 satellites to communicate.

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