BEIJING — Furious that Malaysia has declared their loved ones lost in a plane crash without physical evidence, Chinese relatives of the missing marched Tuesday to the Malaysian Embassy, where they threw plastic water bottles, tried to rush the gate and chanted, “Liars!”

The Chinese government, meanwhile, demanded that Malaysia turn over the satellite data it used to conclude that Malaysia Airlines Flight 370 went down in the southern Indian Ocean with no survivors after turning back from its flight path to Beijing on March 8.

Among the flight’s 239 passengers, 153 were Chinese nationals, making the incident a highly emotional one for Beijing, and the government’s demand reflected the desire among many Chinese relatives of passengers for more conclusive information on the plane’s fate.

Nearly 100 relatives and their supporters marched to the embassy in the late morning, wearing white T-shirts that read “Let’s pray for MH370” as they held banners and chanted for about three hours.

“Tell the truth! Return our relatives!” they shouted. There was a heavy police presence at the embassy, and a brief scuffle when some relatives tried to get past police to approach journalists, but no effort was made to break up the demonstration. The group presented a letter of protest to the embassy before getting into several buses and departing.

Many of the relatives maintain they are not being told the whole truth — a not-uncommon mindset among Chinese accustomed to dealing with authorities in their own opaque, single-party communist state. Though some have expressed resignation that their relatives probably are dead, they have accused Malaysian authorities of foot-dragging and withholding information early in the search, when there might have been some chance to save the plane.

“I want the truth, and I believe they have been hiding some information from us,” said Wang Zhen, who was not part of Tuesday’s demonstration but whose parents were aboard the missing plane. “It remains an enigma as to what happened after the plane turned around. What happened when the plane continued to fly?

“I am still hoping for my parents’ return, even though I understand the probability is very, very low,” Wang said in a telephone interview.

Chinese President Xi Jinping is sending a vice foreign minister to Kuala Lumpur as his special envoy to deal with the matter of the missing plane, the official Xinhua News Agency reported Tuesday.

Deputy Foreign Minister Xie Hangsheng told Malaysia’s ambassador to Beijing that China wanted to know what exactly led Malaysia to announce Monday night that the plane had been lost, China’s Foreign Ministry said on its website Tuesday.

“We demand the Malaysian side to make clear the specific basis on which they come to this judgment,” Xie was quoted as telling Datuk Iskandar Bin Sarudin.

There was no immediate response from the Malaysian side.

The flight vanished less than an hour into an overnight flight March 8 from Kuala Lumpur to Beijing.

In Monday night’s announcement, Malaysian Prime Minister Najib Razak said that an unparalleled study of the jet’s last-known signals to a satellite showed that the missing plane veered “to a remote location, far from any possible landing sites.”

The conclusions were based on a more thorough analysis of the brief signals the plane sent every hour to a satellite belonging to Inmarsat, a British company, even after other communication systems on the jetliner shut down for unknown reasons.

Malaysia Airlines on Tuesday said it was doing everything possible to help the families, and defended itself against criticism over how it informed them about the government’s conclusion that no one aboard the aircraft is still alive. Some relatives were informed by text message.

“Our sole and only motivation last night was to ensure that in the incredibly short amount of time available to us, the families heard the tragic news before the world did,” CEO Ahmad Jauhari Yahya said.

“We know that while there have been an increasing number of apparent leads, definitive identification of any piece of debris is still missing. It is impossible to predict how long this will take,” he said. “But after 17 days, the announcement made last night and shared with the families is the reality which we must now accept.”

Monday’s announcement sparked mournful, angry and chaotic scenes at the Beijing hotel where many relatives had gathered. Around 2:00 a.m. Tuesday (1800 GMT Monday), a group of family members read out a statement accusing Malaysia Airlines and the Malaysian government and military of procrastination and cover-up.

“Such despicable acts have not only fooled but devastated — both mentally and physically — the family members ... but also misled and delayed rescue operations, wasting huge amounts of human power and resources and forgoing the most critical rescue opportunities,” the statement said.

Tuesday’s demonstration at the embassy was unusual for China, where authorities typically clamp down firmly on spontaneous public gatherings that have no prior permission, especially those with any potential to escalate into anti-government protests.

The government’s acquiescence Tuesday shows a double standard on people’s right to assembly, said Beijing lawyer Zhang Qingfang, who represented a prominent activist convicted of disrupting public order after he organized small peaceful rallies demanding education equity and cleaner government.

“The logic, I think, is that as long as it’s directed at the Japanese government or the Malaysian government, it is OK, but it shall not be tolerated if it’s directed at the Chinese government even if the demands are reasonable,” Zhang said. “We still agree the family members have every right and freedom to express themselves, but it is a shame for the government to have such double standards,” he said.

Calls to the news office for the Beijing Public Security Bureau were unanswered. The police also did not respond to a faxed question about whether family members had obtained police permission.

The search for Flight 370 initially centered on the Malay Peninsula, until authorities there announced they had satellite data showing the plane flew on for hours and went much farther afield, going either north toward Central Asia or south to the southern reaches of the Indian Ocean.

Nan Jinyan, sister-in-law of Flight 370 passenger Yan Ling, said she suspects Malaysian authorities knew for a long time that the plane went down in the Indian Ocean.

“I feel like they are toying with human lives,” Nan said. “What else can be more important than human lives?”

Of her brother-in-law, Nan said, “I don’t think there’s any shred of hope for him to return.

“We are exhausted after all those days, and I think we are all at loss as to what to do. We have never been through anything like this, and we have no direction.” Washington Post

BEIJING — Furious that Malaysia has declared their loved ones lost in a plane crash without physical evidence, Chinese relatives of the missing marched Tuesday to the Malaysian Embassy, where they threw plastic water bottles, tried to rush the gate and chanted, “Liars!”

The Chinese government, meanwhile, demanded that Malaysia turn over the satellite data it used to conclude that Malaysia Airlines Flight 370 went down in the southern Indian Ocean with no survivors after turning back from its flight path to Beijing on March 8.

Among the flight’s 239 passengers, 153 were Chinese nationals, making the incident a highly emotional one for Beijing, and the government’s demand reflected the desire among many Chinese relatives of passengers for more conclusive information on the plane’s fate.

Nearly 100 relatives and their supporters marched to the embassy in the late morning, wearing white T-shirts that read “Let’s pray for MH370” as they held banners and chanted for about three hours.

“Tell the truth! Return our relatives!” they shouted. There was a heavy police presence at the embassy, and a brief scuffle when some relatives tried to get past police to approach journalists, but no effort was made to break up the demonstration. The group presented a letter of protest to the embassy before getting into several buses and departing.

Many of the relatives maintain they are not being told the whole truth — a not-uncommon mindset among Chinese accustomed to dealing with authorities in their own opaque, single-party communist state. Though some have expressed resignation that their relatives probably are dead, they have accused Malaysian authorities of foot-dragging and withholding information early in the search, when there might have been some chance to save the plane.

“I want the truth, and I believe they have been hiding some information from us,” said Wang Zhen, who was not part of Tuesday’s demonstration but whose parents were aboard the missing plane. “It remains an enigma as to what happened after the plane turned around. What happened when the plane continued to fly?

“I am still hoping for my parents’ return, even though I understand the probability is very, very low,” Wang said in a telephone interview.

Chinese President Xi Jinping is sending a vice foreign minister to Kuala Lumpur as his special envoy to deal with the matter of the missing plane, the official Xinhua News Agency reported Tuesday.

Deputy Foreign Minister Xie Hangsheng told Malaysia’s ambassador to Beijing that China wanted to know what exactly led Malaysia to announce Monday night that the plane had been lost, China’s Foreign Ministry said on its website Tuesday.

“We demand the Malaysian side to make clear the specific basis on which they come to this judgment,” Xie was quoted as telling Datuk Iskandar Bin Sarudin.

There was no immediate response from the Malaysian side.

The flight vanished less than an hour into an overnight flight March 8 from Kuala Lumpur to Beijing.

In Monday night’s announcement, Malaysian Prime Minister Najib Razak said that an unparalleled study of the jet’s last-known signals to a satellite showed that the missing plane veered “to a remote location, far from any possible landing sites.”

The conclusions were based on a more thorough analysis of the brief signals the plane sent every hour to a satellite belonging to Inmarsat, a British company, even after other communication systems on the jetliner shut down for unknown reasons.

Malaysia Airlines on Tuesday said it was doing everything possible to help the families, and defended itself against criticism over how it informed them about the government’s conclusion that no one aboard the aircraft is still alive. Some relatives were informed by text message.

“Our sole and only motivation last night was to ensure that in the incredibly short amount of time available to us, the families heard the tragic news before the world did,” CEO Ahmad Jauhari Yahya said.

“We know that while there have been an increasing number of apparent leads, definitive identification of any piece of debris is still missing. It is impossible to predict how long this will take,” he said. “But after 17 days, the announcement made last night and shared with the families is the reality which we must now accept.”

Monday’s announcement sparked mournful, angry and chaotic scenes at the Beijing hotel where many relatives had gathered. Around 2:00 a.m. Tuesday (1800 GMT Monday), a group of family members read out a statement accusing Malaysia Airlines and the Malaysian government and military of procrastination and cover-up.

“Such despicable acts have not only fooled but devastated — both mentally and physically — the family members ... but also misled and delayed rescue operations, wasting huge amounts of human power and resources and forgoing the most critical rescue opportunities,” the statement said.

Tuesday’s demonstration at the embassy was unusual for China, where authorities typically clamp down firmly on spontaneous public gatherings that have no prior permission, especially those with any potential to escalate into anti-government protests.

The government’s acquiescence Tuesday shows a double standard on people’s right to assembly, said Beijing lawyer Zhang Qingfang, who represented a prominent activist convicted of disrupting public order after he organized small peaceful rallies demanding education equity and cleaner government.

“The logic, I think, is that as long as it’s directed at the Japanese government or the Malaysian government, it is OK, but it shall not be tolerated if it’s directed at the Chinese government even if the demands are reasonable,” Zhang said. “We still agree the family members have every right and freedom to express themselves, but it is a shame for the government to have such double standards,” he said.

Calls to the news office for the Beijing Public Security Bureau were unanswered. The police also did not respond to a faxed question about whether family members had obtained police permission.

The search for Flight 370 initially centered on the Malay Peninsula, until authorities there announced they had satellite data showing the plane flew on for hours and went much farther afield, going either north toward Central Asia or south to the southern reaches of the Indian Ocean.

Nan Jinyan, sister-in-law of Flight 370 passenger Yan Ling, said she suspects Malaysian authorities knew for a long time that the plane went down in the Indian Ocean.

“I feel like they are toying with human lives,” Nan said. “What else can be more important than human lives?”

Of her brother-in-law, Nan said, “I don’t think there’s any shred of hope for him to return.

“We are exhausted after all those days, and I think we are all at loss as to what to do. We have never been through anything like this, and we have no direction.” Washington Post

A couple of people yesterday said to me that they’d heard that the plane had been found. Not so. Not even close. We do not know where the plane is, nor why it veered off course.

But you might have gotten the impression that the plane was found based on the news from Malaysia, where the prime minister, Najib Razak, announced that Malaysia Airlines Flight 370 went down in the southern Indian Ocean. 

Simultaneously, there have been multiple reports of possible debris being spotted on the surface of the water in several locations roughly 1,500 miles from Perth, Australia.

Let’s be clear: The debris reports are ambiguous at best. The ocean is covered with “marine litter.” The fact that planes and satellites have spotted objects on the surface of the ocean is not surprising. 

Nothing has been seen that closely matches objects associated with an aircraft or with this flight in particular.

The conclusion that the plane went down in the southern Indian Ocean is based on an innovative interpretation of the “handshake” between the airplane and a ground station as relayed by a geostationary satellite. 

We have known for nearly two weeks that this satellite information led investigators to believe that the plane kept flying for at least six hours. 

Last week in our story on satellites, we reported that the northern corridor was eliminated not through any technical analysis, but simply through a survey of the radar coverage on the Asian mainland, which picked up no sign of a stray Boeing 777. 

For six hours after all communication from the airplane ceased March 8, it continued to engage in a computer “handshake” with a satellite that orbits the Earth 22,000 miles above the surface. 

The satellite always remains above the same point on the equator in the Indian Ocean. Inmarsat, the satellite company, examined the “pings” transmitted from the airplane every hour and, according to the company’s senior vice president, Christopher McLaughlin, detected a Doppler shift in the radio waves. (A Doppler shift is what causes the perceived change in the sound of, say, a passing train or ambulance.)

The analysts concluded that the airplane was moving away from the satellite. That, by itself, did not reveal whether the plane was flying north to Asia or south to the Indian Ocean.

But, with help from an unnamed European aerospace expert and from Boeing, Inmarsat scrutinized the pings from other Malaysia Airlines Boeing 777s flying to the north and to the south.

“In looking at the two plots, the correlation between the pings that we found and the southern route plot is absolutely the most compelling. The northern route has no correlation,” McLaughlin said.

And there was more information squeezed from those enigmatic signals: The pings indicated that the plane was flying at a constant altitude and speed, which McLaughlin said “sort of points to it being on autopilot.”

The plane typically flies on autopilot at 450 nautical mph, he said. That gave authorities a rough idea of how far the jet is likely to have flown. 

There were six hourly pings after the plane disappeared, but not a seventh because the aircraft presumably ran out of fuel.

Today, Malaysian authorities released more technical information about this investigation. This originates with the British Air Accidents Investigation Branch (AAIB). An excerpt:

In recent days Inmarsat developed a second innovative technique which considers the velocity of the aircraft relative to the satellite. 

Depending on this relative movement, the frequency received and transmitted will differ from its normal value, in much the same way that the sound of a passing car changes as it approaches and passes by. 

This is called the Doppler effect. The Inmarsat technique analyses the difference between the frequency that the ground station expects to receive and that actually measured. 

This difference is the result of the Doppler effect and is known as the Burst Frequency Offset.

The Burst Frequency Offset changes depending on the location of the aircraft on an arc of possible positions, its direction of travel, and its speed. In order to establish confidence in its theory, Inmarsat checked its predictions using information obtained from six other B777 aircraft flying on the same day in various directions. There was good agreement.

While on the ground at Kuala Lumpur airport, and during the early stage of the flight, MH370 transmitted several messages. 

At this stage the location of the aircraft and the satellite were known, so it was possible to calculate system characteristics for the aircraft, satellite, and ground station.

During the flight the ground station logged the transmitted and received pulse frequencies at each handshake. 

Knowing the system characteristics and position of the satellite it was possible, considering aircraft performance, to determine where on each arc the calculated burst frequency offset fit best.

The analysis showed poor correlation with the Northern corridor, but good correlation with the Southern corridor, and depending on the ground speed of the aircraft it was then possible to estimate positions at 0011 UTC, at which the last complete handshake took place. 

I must emphasise that this is not the final position of the aircraft.

There is evidence of a partial handshake between the aircraft and ground station at 0019 UTC. At this time this transmission is not understood and is subject to further ongoing work.

No response was received from the aircraft at 0115 UTC, when the ground earth station sent the next log on / log off message. This indicates that the aircraft was no longer logged on to the network.

Therefore, some time between 0011 UTC and 0115 UTC the aircraft was no longer able to communicate with the ground station. This is consistent with the maximum endurance of the aircraft.

Obviously this does not answer the question of what happened on the plane as it was flying toward China, or where it ultimately wound up. 

It just indicates that it went south, far into the southern Indian Ocean. There is nothing out there, and thus all signs point to a crash at sea. It’s a terrible and tragic event, and still slathered in mystery.

Now comes more analysis to try to refine the likely location of the plane when it made its final handshake. 

Navy vessels will drag a ping detector to see if they can pick up a signal from the plane on the ocean floor. Time is precious: The pinger runs on batteries and will go silent after roughly 30 days. Washington Post

A couple of people yesterday said to me that they’d heard that the plane had been found. Not so. Not even close. We do not know where the plane is, nor why it veered off course.

But you might have gotten the impression that the plane was found based on the news from Malaysia, where the prime minister, Najib Razak, announced that Malaysia Airlines Flight 370 went down in the southern Indian Ocean. 

Simultaneously, there have been multiple reports of possible debris being spotted on the surface of the water in several locations roughly 1,500 miles from Perth, Australia.

Let’s be clear: The debris reports are ambiguous at best. The ocean is covered with “marine litter.” The fact that planes and satellites have spotted objects on the surface of the ocean is not surprising. 

Nothing has been seen that closely matches objects associated with an aircraft or with this flight in particular.

The conclusion that the plane went down in the southern Indian Ocean is based on an innovative interpretation of the “handshake” between the airplane and a ground station as relayed by a geostationary satellite. 

We have known for nearly two weeks that this satellite information led investigators to believe that the plane kept flying for at least six hours. 

Last week in our story on satellites, we reported that the northern corridor was eliminated not through any technical analysis, but simply through a survey of the radar coverage on the Asian mainland, which picked up no sign of a stray Boeing 777. 

For six hours after all communication from the airplane ceased March 8, it continued to engage in a computer “handshake” with a satellite that orbits the Earth 22,000 miles above the surface. 

The satellite always remains above the same point on the equator in the Indian Ocean. Inmarsat, the satellite company, examined the “pings” transmitted from the airplane every hour and, according to the company’s senior vice president, Christopher McLaughlin, detected a Doppler shift in the radio waves. (A Doppler shift is what causes the perceived change in the sound of, say, a passing train or ambulance.)

The analysts concluded that the airplane was moving away from the satellite. That, by itself, did not reveal whether the plane was flying north to Asia or south to the Indian Ocean.

But, with help from an unnamed European aerospace expert and from Boeing, Inmarsat scrutinized the pings from other Malaysia Airlines Boeing 777s flying to the north and to the south.

“In looking at the two plots, the correlation between the pings that we found and the southern route plot is absolutely the most compelling. The northern route has no correlation,” McLaughlin said.

And there was more information squeezed from those enigmatic signals: The pings indicated that the plane was flying at a constant altitude and speed, which McLaughlin said “sort of points to it being on autopilot.”

The plane typically flies on autopilot at 450 nautical mph, he said. That gave authorities a rough idea of how far the jet is likely to have flown. 

There were six hourly pings after the plane disappeared, but not a seventh because the aircraft presumably ran out of fuel.

Today, Malaysian authorities released more technical information about this investigation. This originates with the British Air Accidents Investigation Branch (AAIB). An excerpt:

In recent days Inmarsat developed a second innovative technique which considers the velocity of the aircraft relative to the satellite. 

Depending on this relative movement, the frequency received and transmitted will differ from its normal value, in much the same way that the sound of a passing car changes as it approaches and passes by. 

This is called the Doppler effect. The Inmarsat technique analyses the difference between the frequency that the ground station expects to receive and that actually measured. 

This difference is the result of the Doppler effect and is known as the Burst Frequency Offset.

The Burst Frequency Offset changes depending on the location of the aircraft on an arc of possible positions, its direction of travel, and its speed. In order to establish confidence in its theory, Inmarsat checked its predictions using information obtained from six other B777 aircraft flying on the same day in various directions. There was good agreement.

While on the ground at Kuala Lumpur airport, and during the early stage of the flight, MH370 transmitted several messages. 

At this stage the location of the aircraft and the satellite were known, so it was possible to calculate system characteristics for the aircraft, satellite, and ground station.

During the flight the ground station logged the transmitted and received pulse frequencies at each handshake. 

Knowing the system characteristics and position of the satellite it was possible, considering aircraft performance, to determine where on each arc the calculated burst frequency offset fit best.

The analysis showed poor correlation with the Northern corridor, but good correlation with the Southern corridor, and depending on the ground speed of the aircraft it was then possible to estimate positions at 0011 UTC, at which the last complete handshake took place. 

I must emphasise that this is not the final position of the aircraft.

There is evidence of a partial handshake between the aircraft and ground station at 0019 UTC. At this time this transmission is not understood and is subject to further ongoing work.

No response was received from the aircraft at 0115 UTC, when the ground earth station sent the next log on / log off message. This indicates that the aircraft was no longer logged on to the network.

Therefore, some time between 0011 UTC and 0115 UTC the aircraft was no longer able to communicate with the ground station. This is consistent with the maximum endurance of the aircraft.

Obviously this does not answer the question of what happened on the plane as it was flying toward China, or where it ultimately wound up. 

It just indicates that it went south, far into the southern Indian Ocean. There is nothing out there, and thus all signs point to a crash at sea. It’s a terrible and tragic event, and still slathered in mystery.

Now comes more analysis to try to refine the likely location of the plane when it made its final handshake. 

Navy vessels will drag a ping detector to see if they can pick up a signal from the plane on the ocean floor. Time is precious: The pinger runs on batteries and will go silent after roughly 30 days. Washington Post

In a statement Monday, Malaysian Prime Minister Najib Razak announced that the latest data appeared to show that Flight MH370 had ended in the southern Indian Ocean.

While there's still little concrete evidence of exactly where the plane is, it appears to have been the first definitive statement on what happened to the Malaysia Airlines flight from authorities, which disappeared en route from Kuala Lumpur to Beijing on March 8.

A meeting with Chinese relatives of the passengers on board MH370 and representatives of Malaysia Airlines was held before the announcement in Kuala Lumpur, according to the New York Times, and relatives were also reportedly sent a text message from the airline. Here's a screen-shot of one from Adrienne Mong of NBC News.

Both Malaysia Airlines and the Malaysian government have been criticized for their handling of MH370's disappearance. Whatever the practical benefits of using a text message to inform families that their loved ones were thought to be dead, it seems likely this move may also be criticized. Washington Post

In a statement Monday, Malaysian Prime Minister Najib Razak announced that the latest data appeared to show that Flight MH370 had ended in the southern Indian Ocean.

While there's still little concrete evidence of exactly where the plane is, it appears to have been the first definitive statement on what happened to the Malaysia Airlines flight from authorities, which disappeared en route from Kuala Lumpur to Beijing on March 8.

A meeting with Chinese relatives of the passengers on board MH370 and representatives of Malaysia Airlines was held before the announcement in Kuala Lumpur, according to the New York Times, and relatives were also reportedly sent a text message from the airline. Here's a screen-shot of one from Adrienne Mong of NBC News.

Both Malaysia Airlines and the Malaysian government have been criticized for their handling of MH370's disappearance. Whatever the practical benefits of using a text message to inform families that their loved ones were thought to be dead, it seems likely this move may also be criticized. Washington Post