Confusion over plane's messages: Who got them?

01:03, Mar 15 2014
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Journalists attempt to interview a woman who is the relative of a passenger on Malaysia Airlines flight MH370, as she crouches on the floor crying, at the Beijing Capital International Airport.
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A relative of a passenger onboard Malaysia Airlines flight MH370 cries, surrounded by journalists, at the Beijing Capital International Airport on March 8, 2014.
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The Malaysia Airlines flight carrying 227 passengers and 12 crew lost contact with air traffic controllers early on Saturday en route from Kuala Lumpur to Beijing, the airline said in a statement.
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An aerial view of an oil spill is seen from a Vietnamese Air Force aircraft in the search area for a missing Malaysia Airlines plane, 250 km from Vietnam and 190 km from Malaysia, in this handout photo from Thanh Nien Newpaper taken on March 8.
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A spokesman (centre) of Malaysia Airlines is surrounded by journalists as he gives a briefing about Malaysia Airlines flight MH370, at a hotel in Beijing March 8, 2014.
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A relative (front) of a passenger of Malaysia Airlines flight MH370 cries as she walks past journalists at a hotel in Beijing March 9, 2014. The Malaysia Airlines Boeing 777-200ER aircraft carrying 227 passengers and 12 crew was presumed to have crashed off the Vietnamese coast on Saturday.
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Malaysia Airlines Commercial Director Hugh Dunleavy (centre) speaks to journalists about information of Malaysia Airlines flight MH370.
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Vietnamese Air Force officers sit in the cockpit of a search and rescue aircraft as they fly over the search area for a missing Malaysia Airlines plane.
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Volunteer rescue workers and religious organisations pray during multi-religion mass prayers for the passengers of Malaysian Airlines flight MH370, at the Kuala Lumpur International Airport in Sepang.
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A view of oil slicks (pale line near the bottom right) spotted in an area of the South China Sea about 100 nautical miles (185 km) from Tok Bali Beach in Malaysia's Kelantan state.
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Admiral Datuk Mohd Amdan Kurish, Director General of the Malaysian Maritime Enforcement Agency, looks at a radar screen while searching for a missing Malaysia Airlines plane in the South China Sea.
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A relative (left) of a passenger of Malaysia Airlines flight MH370 is escorted by a caregiver from Malaysia Airlines as they walk in a corridor at a hotel in Beijing.
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Indian sand artist Sudarshan Patnaik applies the final touches to a sand art sculpture he created wishing for the well being of the passengers of Malaysian Airlines flight MH370, on a beach in Puri, in the eastern Indian state of Odisha.
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Life vests and lifesavers are seen onboard a Vietnam Air Force search and rescue aircraft on a mission to find the missing Malaysia Airlines flight MH370, off Tho Chu island.
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Journalists place their recorders as they get ready for the first briefing of the day at a news conference at the Kuala Lumpur International Airport in Sepang on March 10.
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Relatives of a passenger onboard the missing Malaysia Airlines flight MH370 cry inside a hotel they are staying, in Putrajaya. China has urged Malaysia to step up the search for the jetliner that went missing with 239 people on board, about two-thirds of them Chinese, and said it has sent security agents to help with an investigation into the misuse of passports.
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An officer looks out of a helicopter during a mission to find the Malaysia Airlines flight MH370 that disappeared from radar screens in the early hours of Saturday, near Tho Chu Island.
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A map of a flight plan is seen on a computer screen during a meeting before a mission to find the Malaysia Airlines flight MH370 that disappeared from radar screens in the early hours of Saturday, at Phu Quoc Airport.
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A woman stands in front of a giant screen showing the number hours since Malaysia Airlines flight MH370 went missing, in Beijing on March 10.
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A family member of a passenger from the missing Malaysia Airlines flight MH370 waits for news at Lido Hotel on March 10, in Beijing, China. Investigative teams continue to search for the missing Malaysia Airlines flight MH370 and the 293 passengers that were travelling from Kuala Lumpur to Beijing.
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Dato' Azharuddin Abdul Rahman, director general of the Malaysian Department of Civil Aviation briefs the media over latest updates on missing Malaysia Airline MH370 on March 10, in Kuala Lumpur.
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Clouds hover outside the window of a Vietnam Air Force search and rescue aircraft An-26 on a mission to find the missing Malaysia Airlines flight MH370, off Vietnam's Tho Chu island.
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People believed to be relatives of passengers of the missing Malaysia Airlines flight MH370 are escorted to the VIP section of the Beijing Capital International Airport prior to flying to Kuala Lumpur.
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A Chinese relative of a passenger of Malaysia Airlines MH370 is comforted by a staff member of the airport as she shields her face from journalists at Kuala Lumpur International Airport.
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A combination photo shows two men whom police said were travelling on stolen passports onboard the missing Malaysia Airlines MH370 plane.
Military personnel look out of a Singapore Air Force plane during the search
Military personnel look out of a Singapore Air Force plane during the search.
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Malaysia's police chief, Inspector General Khalid Abu Bakar, addresses a news conference.
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Students from an international school in east China city Zhuji pray for the passengers onboard Malaysia Airlines flight MH370.
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LOOKING FOR ANSWERS: Family members of missing passengers leave a meeting in a Beijing Hotel.
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MESSAGE OF HOPE: A Vietnamese tourist writes a message of hope for missing passengers and crew.
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MESSAGES FOR THE MISSING: Tying a message of hope on a message board for passengers and crew.
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A relative of a passenger aboard Malaysia Airlines flight MH370 answers media questions at Lido Hotel.
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A charity worker comforts an emotional relative of a passenger.
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Indian sand artist Sudarshan Pattnaik works on a sand sculpture of missing Malaysia Airlines flight MH370, at golden beach at Puri in the eastern Indian state of Odisha.
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Satellite images reveal a possible crash site for the missing Malaysia Airlines plane, where three large objects were seen in the water.
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An object sits in the water in satellite imagery released by China.
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The zone where the mystery objects were found.
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What appears to be fuel sits on the water in the area where three large objects were found.
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A crew member from the Royal Malaysian Air Force looks through the window of a Malaysian Air Force CN235 aircraft during a Search and Rescue operation to find the missing Malaysia Airlines flight MH370.
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The Arleigh Burke-class guided-missile destroyers USS Kidd and USS Pinckney are seen en transit in the Pacific Ocean in this US Navy picture taken May 18, 2011. Kidd and Pinkney have been searching for the missing Malaysian airliner and are being re-deployed to the Strait of Malacca off Malaysia's west coast as new search areas are opened in the Indian Ocean.
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Students watch as a group of artists put the finishing touches to a three dimensional artwork at a school in Makati city, metro Manila. According to the artists, the artwork is their way of expressing sympathy towards the relatives of passengers onboard the missing Boeing 777-200ER.
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Malaysia's acting Transport Minister Hishammuddin Hussein shows two maps with corridors of the last known possible location of the missing plane.
Selamat Omar shows a picture of his son, flight engineer Mohd Khairul Amri Selamat
Selamat Omar shows a picture of his son, flight engineer Mohd Khairul Amri Selamat who was onboard the missing Malaysia Airlines Flight MH370.
Chinese relatives of the missing passengers
Chinese relatives of the missing passengers who were travelling onboard Malaysia Airlines flight MH370 watch a television displaying a Malaysian press conference at Lido Hotel in Beijing.
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A family member of a passenger onboard the missing Malaysia Airlines flight MH370 cries as he watches a message board dedicated to passengers.
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Satellite photos from March 20 show the objects "possibly associated" with the search for the missing plane. The images were released hours after Australia announced it had "credible" leads in the search for flight MH370.
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Satellite photos from March 20 show the objects "possibly associated" with the search for the missing plane. The images were released hours after Australia announced it had "credible" leads in the search for flight MH370.
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A still image taken from video shows an image of an object spotted in the southern Indian Ocean by the Gaofen-1 high-resolution optical Earth observation satellite of CNSA.
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Pilot Dave Smith (R) gives a pre-flight briefing aboard a Royal New Zealand Air Force P-3K2 Orion aircraft before taking off to search for missing Malaysian Airlines flight MH370, at RAAF base Pearce near Perth, March 22, 2014.
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Family members of passengers onboard Malaysia Airlines Flight MH370 raise their fists as they shout "return our families" to protest against the lack of new information after a routine briefing given by Malaysia's government and military representatives at Lido Hotel in Beijing March 22, 2014.
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Malaysia's acting Transport Minister Hishammuddin Hussein holds up a note that he has just received on a new lead in the search for the missing Malaysia Airlines Flight MH370, during a news conference at Kuala Lumpur International Airport March 22, 2014.
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Malaysia's Prime Minister Najib Razak (bottom C) takes part in a special prayer for passengers onboard the missing Malaysia Airlines Flight MH370 at the Tuanku Mizan Zainal Abidin mosque in Putrajaya March 21, 2014.
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A woman writes on a banner of well wishes for the passengers of the missing Malaysia Airlines Flight MH370 at Kuala Lumpur International Airport March 14, 2014.
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A family member of a passenger onboard Malaysia Airlines Flight MH370 covers her face as she cries after a routine briefing given by Malaysia Airlines at Lido Hotel in Beijing, March 22, 2014.
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A girl reads some of the messages of hope and support for the passengers of the missing Malaysia Airlines MH370 at a mall outside Kuala Lumpur March 22, 2014.
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A crew member aboard a Royal Australian Air Force (RAAF) AP-3C Orion uses binoculars as it flies over the southern Indian Ocean during the search for missing Malaysian Airlines flight MH370 March 22, 2014.
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A woman writes another message of hope and support for the passengers of the missing Malaysia Airlines MH370 at a mall outside Kuala Lumpur March 22, 2014.
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Map of the southern Indian Ocean locating site where a satellite may have found debris related to Malaysia Airlines Flight 370; includes satellite images of possible debris. MCT
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Solid matter is pictured floating in the southern Indian Ocean seen from a Royal New Zealand Air Force P-3K2 Orion aircraft searching for missing Malaysian Airlines flight MH370.
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INDIAN OCEAN - This handout Satellite image made available by the AMSA (Australian Maritime Safety Authority) shows a map of the planned search area for missing Malaysian Airlines Flight MH370 on March 24, 2014.
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Malaysia's acting Transport Minister Hishammuddin Hussein holds satellite images as he speaks about the search for the missing Malaysia Airlines flight MH370 on March 26.
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A satellite photo, showing the locations and co-ordinates of unknown objects reported by the Malaysian Remote Sensing Agency (MRSA) in the Indian Ocean. The images were taken on March 23 and released on March 26.
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A satellite photo, showing the location of unknown objects reported by the Malaysian Remote Sensing Agency (MRSA) in the Indian Ocean. The images were taken on March 23 and released on March 26.

For three minutes, as a giant airliner began a plunge to its demise in the ocean, the plane sent out a series of frantic messages - 29 of them - alerting its home base that it was in trouble.

They came not from the pilots, who were struggling to control the wildly bucking aircraft, or the black box that later would reveal their crisis when retrieved from the ocean floor.

Those messages in 2009 came through an automatic system known as ACARS - or more formally, the Aircraft Communications Addressing and Reporting System.

That is the system that US officials said provided data indicating that the twin engines on Malaysia Airlines Flight 370 continued to function for as long as four hours after the transponder sending radar signals went dark.

Though the 2009 flight, an Air France Airbus A330 with 228 people on board, crashed into the Atlantic Ocean largely intact, it was five days before a massive search effort turned up significant wreckage.

The transmissions sent via ACARS in that flight's final minutes were error messages that went to Air France's home base, sent there on the assumption that mechanics would correct the problem once the flight arrived.

The aftermath of the Malaysia Airlines disappearance Saturday has been fraught with confusion and contradictory reports. Officials with the airline and the engine manufacturer, Rolls-Royce, denied that they had received messages from the plane's engines indicating that they had continued to operate.

In addition to its radar transponder, which went dark at 1.07am Saturday, and its radio, which fell silent 26 minutes after takeoff from Kuala Lumpur, the plane may have been equipped with three other modes of nonverbal communication.

It could have sent signals via UHF radio, a line-of-sight system that lacks the capacity to see beyond the horizon and seems unlikely to have been effective on the Malaysia flight. It was almost out of range for the radar used by Malaysian air traffic controllers, whose radar also is a line-of-sight system.

It also might have signalled on VHF radio, which bounces off the atmosphere, carrying a less potent signal much farther.

But ACARS provides the best method for a modern aircraft to send short automatic reports on how its systems are functioning. It is a digital datalink that can be transmitted either by radio or via satellite, and was first deployed in 1978 by Aeronautical Radio (ARINC), a division of US aerospace giant Rockwell-Collins.

There are several places to which the data stream can be directed by ACARS: The manufacturer of the plane - for Malaysia Airlines, that's Boeing - the company that built the engines, or the airline operating that plane.

"That gets down to what the airline chooses to have," said a consultant for another aviation engine maker who asked not to be identified so that he could speak candidly.

Malaysia Airlines has not revealed how its data stream is packaged or where it is sent, adding to the confusion over who might have the best available information.

Air France received that information from the 2009 flight directly, but not all airlines do.

"Air France is a big, sophisticated airline with a very advanced maintenance facility in France," the consultant said. "But some of these less-established airlines have power by the hour."

Under that scheme, an engine manufacturer leases the engines to the airline. In that circumstance, the manufacturer is likely to receive engine data directly.

"The deal is that, for every hour you use this engine, you pay us X thousand dollars," he said. "All the maintenance is included in the package. The engine maker's real profit is in the ongoing service/overhaul. They may sell the engine at break-even just to get the ongoing business."

All of the corporations involved - Malaysia Airlines, Boeing and Rolls-Royce - have reason to be circumspect about the data they release publicly. The history of aviation liability is replete with lawsuits filed against all parties involved in a disaster.

One notable example is the 1997 crash of a SilkAir flight in Indonesia that killed 104 people.

Although the US National Transportation Safety Board concluded that a suicidal co-pilot intentionally caused the crash, families brought suit against Boeing in a California court, claiming the cause was a rudder-control defect. They won an out-of-court settlement with the company.

- Washington Post

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