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How investigators pull data from the black boxes of a Boeing 737



In the five days since Ethiopian Airlines Flight 302 crashed a few minutes after the departure of Addis Ababa and killed all 157 people on board, regulators around the world have grounded the Boeing 737 MAX 8 , This is in response to the fact that the circumstances of this disaster coincide with those of the Lion Air Flight 610, another 737 MAX 8 that crashed into the Java Sea in October, killing all 189 inmates. In order to find out what has actually overturned the Ethiopian jet, the investigators must get to the vital data, which are stored in the two black boxes of the aircraft.

These boxes are the flight data recorder and the cockpit voice recorder. Both use solid state hard drives with memory cards on one board. The first log records all the details that together form a picture of what the aircraft did up to 25 hours before a crash: the positions of various switches, engine settings, airspeed, altitude, and more than 1

,000 other parameters. Look at this data, and "you know what happened to the plane physically," says aviation consultant Kit Darby.

The cockpit voice recorder sounds like this: An audio recording of everything the pilots say and hear. This can often give you the Why crash because it gives the pilots an interpretation of what is going on and how they are reacting. Together with the flight data recorder you can get the whole picture. "You have to combine the two," says Darby.

That's why they are built to survive virtually all crashes. Honeywell, maker of black boxes, says they can survive an impact of up to 3,400G. (If you are not a trained fighter pilot, you may be able to handle about 5 G before falling over.) You can withstand the pressure of 20,000 feet of water for two years. At temperatures up to 1,100 degrees Fahrenheit, as well as ice, they are good. Therefore, neither a regular nor a light dragon can be destroyed.

The Ethiopian Flight 302 cockpit voice recorder and flight recorder arrived in Paris on Thursday Investigators will investigate the data showing what has brought the Boeing 737 MAX 8 to collapse.

Christophe Ena / AP Images

For added safety, the boxes drive in the tail of the aircraft, which is less damaged in a crash than the rest of the aircraft. They are equipped with sonar pimples to make them discoverable when the plane falls over water and sinks to the bottom of the sea. (The Pingers helped the search teams find the two recorders that sank to the bottom of the Java Sea on the crash of the Lion Air 737.) And they are bright orange to make them easier to spot.

The Ethiopian Flight 302 crashed relatively flat and open terrain, so the investigators found the black boxes within a day. Since special lab equipment is required to access their data, the boxes were sent to Paris, where the French civil aviation investigator, Bureau d & # 39; Enquêtes & d & # 39; Analyses, will handle them. They arrived on Thursday morning and the technical work to access their data began on Friday. In a photo published by the French agency, the flight data recorder looks pretty mangled . This is not surprising for something that happened in a plane crash – they are built to survive and not look pretty. And in most cases, the crushed mess is not a big problem.

The BEA lab staff first open each box and remove the 2.5 cm thick thermal insulation layer inside. Once you have removed the memory board, place it under a microscope – some components are just a few millimeters wide – and look for damage. Then place them in an x-ray machine to examine what they can not see with the microscope.

This is a relatively simple recovery operation, but sometimes black boxes are hard to find and hard to rescue. Take the case of Air France 447, the Airbus A330, crashed in 2009 off the coast of Brazil with 228 people in the Atlantic. The investigators needed two years to find the destroyed plane and its black boxes, which were below 13,000 feet of water. The fact that an international team has been hunting for so long shows you how strongly the Skylords think about what causes crashes and how to prevent them from happening again.

And the fact that the Air France planes are Black Boxes Underwater burial has made everyone realize how hard they are as mothers. In fact, the flight data recorder worked well. The cockpit voice recorder was in a bit worse condition. The French team reported a cracked capacitor and resistor as well as damage to two "decoder-type" components. Before doing anything else, the team puts the memory cards in an oven to remove moisture (36 hours for the flight recorder, 42 for the cockpit voice recorder). Then the damaged bits were removed and new ones soldered in. Although it is technical work, it is by no means impossible.

Other types of damage are not that easy to fix, says Darby. "If the card is squashed, you can not read it." And damage to the memory card itself is more worrying than anything that can happen to the other parts of the board. "This may or may not be recoverable."

In the case of Air France 447, after the memory boards were completely dry, the lab assistants screwed the cards to their readers. (You are one of the few places in the world to have one, and the Laboratory of the National Transportation Safety Board in Washington, DC is another one.) You downloaded and synchronized the data. Then they set to work to find out what crashed the jet. One year later, in 2012, they published their final report. The plane stopped at cruising altitude after the ice clogged the speed sensors, the autopilot shut down and the pilots misunderstood the situation.

Now that the black boxing process is starting in Paris, the results could show what stopped Ethiopia from flight 302 and led to the grounding of the world's Boeing 737 MAX jets. Nothing will happen fast. Full investigations usually take about 18 months – but preliminary data released before that time can shed light on what happened.


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