When Ethiopian Airlines Flight ET409 crashed into the sea on January 25, 2010 just minutes after taking off from Beirut (BEY), all 82 passengers, and 8 crew members aboard the Boeing 737-800 perished. These included 51 travelers from Lebanon, 31 passengers and crew from Ethiopia, 2 from the U.K., and 1 each from Canada, France, Iraq, Russia, Syria, and Turkey. Almost a month after the fatal crash, many questions still remain unanswered.
Amidst all the broken fragments of the aircraft, and the recovered bodies, two objects survived: the plane’s Flight Data Recorder and Solid-State Cockpit Voice Recorder. Commonly called “Black Boxes”, both are presently being analyzed by the Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA), an agency of the French government located near Paris.
CAPTIONS: (ABOVE LEFT) A plastic doll lies amidst other debris collected from the sea by soldiers and other emergency personnel, following the Ethiopian Airlines plane crash, on Khalde beach south of Beirut, in Lebanon, Monday, January 25, 2010 (AP Photo/Ben Curtis); (BELOW RIGHT) A cousin of Ethiopian Airlines plane crash victims Fuad and Abbas Jaber release balloons as she mourns on the beach in Khalde, south of Beirut, Lebanon, Friday, Jan. 29, 2010 (AP Photo/Hussein Malla); (BELOW LEFT) Ethiopian Airlines CEO Girma Wake speaks to journalists in Addis Ababa, Ethiopia on Monday, January 25, 2010 (AP Photo/Samson Haileyesus); (BELOW RIGHT LOWER) Cockpit Voice Recorder (CVR) made by Honeywell Aerospace (Image from Honeywell Aerospace, used with permission); (BELOW LEFT LOWER) International Civil Aviation Organization (ICAO) HQ in Montreal, Canada (Wikipedia/Common Usage); (BELOW RIGHT BOTTOM) Ethiopian women, relatives and friends of passengers of an Ethiopian Airlines plane that crashed in the sea on January 25, gather at Rafik Hariri University Hospital as they watching the Ethiopian consulate receive the recovered bodies of five nationals who were killed in the plane, in Beirut, Lebanon, on Saturday Feb. 13, 2010 (AP Photo/Hussein Malla); (BELOW LEFT BOTTOM) In this photo released by the Lebanese army, Lebanese soldiers carry the black box of the Ethiopian Arilines jet that crashed off the the Lebanese coast on Jan. 25, which is seen placed in a sea water container shortly after it was pulled out by Lebanese marine commandos, south of Beirut, Lebanon (AP Photo/Lebanese Army, HO)
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BEA provides a similar function as the U.S. NTSB. The French agency has about 120 employees, including 30 investigators and 12 investigative assistants. They are being aided by civil aviation representatives from the governments of Lebanon and Ethiopia. Technical assistance is also being offered by Boeing, the NTSB, and the U.S. Federal Aviation Administration (FAA).
Among those privy to the confidential preliminary findings, one or more individuals leaked the last words spoken by Ethiopian AIrlines Captain Habtamu Benti Negasa. As reported in the Arabic language web site assafir.com, and other news agencies, Captain Benti, speaking in his native Amharic mother tongue, used in North Central Ethiopia, uttered the following last words of his life, “Finished, finished. God have mercy on us.”
To the Airlines/Airport Examiner, and others, it seems a miracle that the cockpit voice recorder could survive such a crash, and bring back messages from beyond the grave. To learn more, we went directly to the source, Honeywell Aerospace, one of the leading suppliers of flight voice and data recorders. Honeywell has shipped more than 14,000 cockpit voice recorders.
Ms. Karen Crabtree, a Media Relations Manager at Honeywell, set up a 3-way conference call interview on Friday, February 19, with myself and Mr. Duncan Schofield, Principal Systems Engineer at Honeywell Aerospace.
Speaking candidly from his offices in Redmond, Washington, these are Mr. Schofield’s responses, given in bold type below:
Q. How can Cockpit Voice Recorders survive crashes?
“The CVR is engineered in two parts. One in a base or carrier, an L-shaped box containing an 8 watt power supply. Bolted to it on four welded feet, is a tube shaped Crash Survivable Memory Unit. The L-shaped base is expendable. The memory unit is designed to survive tremendous forces and pressures, and radio its location through an Underwater Locator Beacon that is attached to it.”
Q. Why not build the CVR as one solid unit to prevent the Memory Unit from separating after a crash and possibly getting lost?
“Since the Memory Unit is completely sealed and enclosed, if it contained an internal power supply, heat would build up without a way to escape and dissipate. That heat would eventually damage the circuit boards and electronics.”
Q. How can I explain to my readers the forces that the CVR can withstand?
“The CVR can resist impact forces of 3,400 G-Force. Such G-Force are produced by changes in motion, acceleration or deceleration. A simple way of explaining this complex dynamic is to point out that a body at rest on Earth is subjected to one G-Force. If a person on Earth weighs, for example 100 pounds, or you can use 100 kilograms instead for metric examples, 3,400 G-force would translate to an equivalent weight of 3,400,000 pounds or kilograms in this illustration.”
Q. Besides the enormous G-forces that are produced in a crash, what other protections are engineered into the CVR?
“Here are the technical specifications: Penetration Resistance of a 500 pound (227 kg) weight from 10 feet (3.048 meters) Static Crush of 5000 pounds (2,268 kilograms), 5 minutes of high temperature fire up to 1,100 degrees Celsius, 60 minutes low temperature fire up to 260 degrees Celsius, 10 hours deep sea pressure of up to 20,000 feet (6,096 meters), and up to 30 days of sea water or fluids immersion.”
Q. How do you test these devices?
“We send the prototypes to specialized laboratories, as well as doing some of the tests ourselves here in Redmond, Washington. Impact shock is tested by shooting a pneumatic gun at a calibrated surface. We drop weights from a tower on the equipment being tested. Deep sea pressure chambers test for water leakage. There are also hot and cold temperature simulations. The engineering drawings used in the manufacturing process specify that each dimensional element is exactly the same, to tolerances of 0.005 to 0.010 of an inch. There are also hardness and other requirements.”
Q. For how long does a CVR record?
“Since 1998 the FAA and international agencies have mandated 2 hours of recording time for all aircraft delivered outside the United States. Older models of the digital CVR are still installed on aircraft that only have 30 minutes of capacity.”
Q. Why would recovered flight recorders be brought to the surface, and transported covered in sea water?
“That would be a good question to ask of the NTSB. There are two factors in play. Historically, early flight recorders used magnetic recoding tape, instead of today’s devices, which are completely solid state and have no moving parts. After a crash, if the tape were to get wet, recovery experts wanted to keep it wet until it could be dried under controlled conditions in a laboratory. That habit may have carried over from the past. Secondly, as sea water is corrosive, a better choice would be to use fresh distilled water.”
Q. Thank you Mr. Schofield and Ms. Crabtree for providing this information, and for your courtesy and valuable time.
“You are most welcome.”
As more facts unfold, including our own investigative inquiries, we will report them to our readers.
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