Malaysia Airlines Flight MH370 Missing

Malaysia said on Monday that a missing jetliner had crashed into the Indian Ocean, an announcement that was greeted with hysteria by Chinese relatives of those on board and a demand by China that Kuala Lumpur share all the evidence it had on the incident.

Citing groundbreaking satellite-data analysis by the British company Inmarsat, Malaysian Prime Minister Najib Razak said that Malaysia Airlines Flight MH370, which vanished more than a fortnight ago while flying to Beijing from Kuala Lumpur, had crashed thousands of miles away in the southern Indian Ocean.

His statement may go some way toward tamping down some of the more fevered speculation about the plane's fate, including one theory some grief-stricken relatives had seized on: that the plane had been hijacked and forced to land somewhere.

All 239 people on board were presumed dead, airline officials said on Monday.

Najib's announcement opens the way for what could be one of the most costly and challenging air crash investigations in history.

The launch of an official air crash investigation would give Malaysia power to coordinate and sift evidence, but it may still face critics, especially China, which had more than 150 citizens on board the missing plane and has criticised Malaysia over the progress of the search.

The Inmarsat data showed the Boeing 777's last position was in the Indian Ocean west of Perth, Australia, Najib said in a statement.

"This is a remote location, far from any possible landing sites," he said. "It is therefore, with deep sadness and regret, that I must inform you that, according to this new data, Flight MH370 ended in the southern Indian Ocean."

Britain's Inmarsat used a wave phenomenon discovered in the 19th century to analyze the seven pings its satellite picked up from Malaysia Airlines Flight MH370 to determine its final destination.

The new findings led Malaysian Prime Minister Najib Razak to conclude on Monday that the Boeing 777, which disappeared more than two weeks ago, crashed thousands of miles away 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 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 interrogated 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," Jonathan Sinnatt, head of corporate communications at Inmarsat, said.

The company then compared its theoretical flight path with data received from Boeing 777s 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 on Monday.

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 (Global Positioning System) could not be used to determine the aircraft's flight path.