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Updated Q. and A. on Malaysia Airlines Flight 370 Updated Q. and A. on Malaysia Airlines Flight 370
(about 7 hours later)
The disappearance of Malaysia Airlines Flight 370 has led to a multinational air and sea search across a vast area of the Indian Ocean. Recently, after weeks of debris sightings that turned out to be irrelevant, sounds have been heard that may be coming from the missing plane, but thus far there has been no confirmation. As the search narrows and the international inquiries into the disappearance continue, Matthew L. Wald, a correspondent for The New York Times, answers some basic questions.The disappearance of Malaysia Airlines Flight 370 has led to a multinational air and sea search across a vast area of the Indian Ocean. Recently, after weeks of debris sightings that turned out to be irrelevant, sounds have been heard that may be coming from the missing plane, but thus far there has been no confirmation. As the search narrows and the international inquiries into the disappearance continue, Matthew L. Wald, a correspondent for The New York Times, answers some basic questions.
Q. Lately, various search ships have reported hearing “pings,” possibly from the the plane’s cockpit voice and data recorders, known as black boxes. Why did the search ships seem to hear the pings as soon as they started listening? Why didn’t the searchers listen for the pings from the beginning?Q. Lately, various search ships have reported hearing “pings,” possibly from the the plane’s cockpit voice and data recorders, known as black boxes. Why did the search ships seem to hear the pings as soon as they started listening? Why didn’t the searchers listen for the pings from the beginning?
A. Some of the reports of pings are certain to be wrong, because they are in widely scattered locations and the plane carried only two pingers. The ocean is noisy, and the most likely explanation is random sounds that resemble pings. The Australian reports of several encounters with repeated pings are the most promising so far. But the ships that listen for the pings do so while traveling very slowly, at only a few miles an hour, and the pings are not loud enough to be heard from a great distance, so there is little point in deploying the ships until you have a good idea where to look. The decision to start listening for pings may have been driven partly by desperation: the listening devices were on hand, and the clock was ticking toward the point where the batteries that power the black boxes’ pingers would be exhausted.A. Some of the reports of pings are certain to be wrong, because they are in widely scattered locations and the plane carried only two pingers. The ocean is noisy, and the most likely explanation is random sounds that resemble pings. The Australian reports of several encounters with repeated pings are the most promising so far. But the ships that listen for the pings do so while traveling very slowly, at only a few miles an hour, and the pings are not loud enough to be heard from a great distance, so there is little point in deploying the ships until you have a good idea where to look. The decision to start listening for pings may have been driven partly by desperation: the listening devices were on hand, and the clock was ticking toward the point where the batteries that power the black boxes’ pingers would be exhausted.
Q. The plane disappeared March 8. How long do the batteries last?Q. The plane disappeared March 8. How long do the batteries last?
A. The rule is they have to be good for 30 days. In practice, they are built with a little extra energy to make sure they meet or exceed that standard, even on the last day before they are released, so 33 to 38 days’ worth of charge is common, or at most 40 days — meaning that Flight 370’s pinger batteries would be expected to run out no later than April 17, and probably before. The company that builds the pingers offers 90-day batteries as an option, but they cost more and weigh more, neither of which appeals to airlines. After this crash, though, regulators may start requiring 90-day batteries.A. The rule is they have to be good for 30 days. In practice, they are built with a little extra energy to make sure they meet or exceed that standard, even on the last day before they are released, so 33 to 38 days’ worth of charge is common, or at most 40 days — meaning that Flight 370’s pinger batteries would be expected to run out no later than April 17, and probably before. The company that builds the pingers offers 90-day batteries as an option, but they cost more and weigh more, neither of which appeals to airlines. After this crash, though, regulators may start requiring 90-day batteries.
Q. What happens when the batteries are drained?Q. What happens when the batteries are drained?
A. Like a flashlight beam, the pinger’s signal will gradually fade. Finding a black box with a pinger is like finding a mislaid cellphone by dialing its number and listening for the ringtone. Once the battery is exhausted, you can still find it, but the job is more difficult.A. Like a flashlight beam, the pinger’s signal will gradually fade. Finding a black box with a pinger is like finding a mislaid cellphone by dialing its number and listening for the ringtone. Once the battery is exhausted, you can still find it, but the job is more difficult.
Q. How do you look for it then?Q. How do you look for it then?
A. Primarily with sonar, which is like radar except that it uses sound waves instead of radio waves. The sound is bounced off the ocean floor and read as it returns. The sonar unit is towed behind a ship, and “flown” at an optimum altitude over the bottom, so that the sea floor is in range but the sonar can “see” the widest practical area. Searchers look for straight lines, right angles and other telltale characteristics of manmade objects that can then be investigated up close using submersible vessels. The sonar images are searched by human eyes, but experts are working on software that can scan such images for clues.A. Primarily with sonar, which is like radar except that it uses sound waves instead of radio waves. The sound is bounced off the ocean floor and read as it returns. The sonar unit is towed behind a ship, and “flown” at an optimum altitude over the bottom, so that the sea floor is in range but the sonar can “see” the widest practical area. Searchers look for straight lines, right angles and other telltale characteristics of manmade objects that can then be investigated up close using submersible vessels. The sonar images are searched by human eyes, but experts are working on software that can scan such images for clues.
Q. Do the black boxes themselves need battery power to retain their data?Q. Do the black boxes themselves need battery power to retain their data?
A. No, they have “nonvolatile” storage, in computer chips.A. No, they have “nonvolatile” storage, in computer chips.
Q. What will happen to the black boxes if they are found?Q. What will happen to the black boxes if they are found?
A. It will depend to some extent on who recovers them. The Malaysian authorities, who by international treaty are in nominal control of the investigation, would probably have to send them abroad for interpretation. The agency with the most experience in examining Boeing black boxes is the National Transportation Safety Board in Washington, but Australia, which is coordinating the ocean search, has the ability as well. In any case, Boeing and the National Transportation Safety Board would assist with the work.A. It will depend to some extent on who recovers them. The Malaysian authorities, who by international treaty are in nominal control of the investigation, would probably have to send them abroad for interpretation. The agency with the most experience in examining Boeing black boxes is the National Transportation Safety Board in Washington, but Australia, which is coordinating the ocean search, has the ability as well. In any case, Boeing and the National Transportation Safety Board would assist with the work.
Q. What happens when artifacts are found?Q. What happens when artifacts are found?
A. In water this deep, the most likely approach is with remote-controlled submarines, equipped with searchlights, video cameras and grapples that can pick up objects.A. In water this deep, the most likely approach is with remote-controlled submarines, equipped with searchlights, video cameras and grapples that can pick up objects.
Q. Why would the authorities not have found floating debris from the plane after so many weeks of searching?Q. Why would the authorities not have found floating debris from the plane after so many weeks of searching?
A. One reason is that much of the searching was done in what the authorities now believe were the wrong places. In the first days, the focus was on the Gulf of Thailand and the South China Sea, close to where the plane was when ground controllers last heard from the pilots or saw signals from its transponders. Military radar data then emerged showing that the plane had turned far off course and flown westward toward the Strait of Malacca and the Andaman Sea, so some searchers were shifted there. Then satellite signals indicated that the plane had kept flying for hours more, hugely expanding the possible search area. By the time the primary focus narrowed again to the southern Indian Ocean, nearly two weeks had gone by, time in which the elements could have scattered or sunk some debris that might have been visible immediately after the crash.A. One reason is that much of the searching was done in what the authorities now believe were the wrong places. In the first days, the focus was on the Gulf of Thailand and the South China Sea, close to where the plane was when ground controllers last heard from the pilots or saw signals from its transponders. Military radar data then emerged showing that the plane had turned far off course and flown westward toward the Strait of Malacca and the Andaman Sea, so some searchers were shifted there. Then satellite signals indicated that the plane had kept flying for hours more, hugely expanding the possible search area. By the time the primary focus narrowed again to the southern Indian Ocean, nearly two weeks had gone by, time in which the elements could have scattered or sunk some debris that might have been visible immediately after the crash.
Q. Will we ever know what happened?Q. Will we ever know what happened?
A. Some investigators are warning that we may never have a conclusive answer. The cockpit voice recorder, if it is found, may not contain anything helpful: It stores only about two hours of sound, and has probably not preserved anything from the moments early in the flight when the cockpit crew stopped communicating with the ground and the plane went off course. And in two previous crashes in which American investigators believe the cause was murder-suicide, involving SilkAir and EgyptAir flights, the countries whose flag the airplanes carried — Indonesia and Egypt — never accepted those findings. A. Some investigators are warning that we may never have a conclusive answer. The cockpit voice recorder, if it is found, may not contain anything helpful: It stores only about two hours of sound, and has probably not preserved anything from the moments early in the flight when the cockpit crew stopped communicating with the ground and the plane went off course. And in two previous crashes in which American investigators believe the cause was murder-suicide, involving SilkAir and EgyptAir flights, the countries whose flag the airplanes carried — Singapore and Egypt — never accepted those findings.