|The Black Box|
THE INFAMOUS BLACK BOX
So, I ask you…… Do manufacturers of the “Black Box” think we all are color blind and geometrically challenged?
First of all, the color of the Black Box is not Black. It’s some kind of reddish, orange and sometimes mixed with yellowish gold colored contraption, a far stretch from Black….
Second of all…. Lets talk about it's shape. It has a cylinder shaped whacha-callit, sitting next to a rectangle or kind of square thinga-ma-jig and they both are sitting on top of a flat doo-hickie. ( to have a look at Black Box click here).
The Black Box is stored in a top secret place on the airplane. I will tell you where it’s stored if you promise not to tell anyone. It’s located in the tail of the airplane. It’s located there because when it was located in the cabin of the airplane, everyone wanted to sit by the Black Box because everyone knows the Black Box has survived the most horrible, devastating crashes…. No I’m joking, that’s is not why it’s located in the tail.
But seriously speaking… I’m often asked….. How does the Black Box always survive an aircraft accident?
In this article, we will look at the two types of Black Boxes (professionally known as Flight Data Recorder (FDR) and the Cockpit Voice Recorder (CVR )), how they survive crashes, and how they are retrieved and analyzed.
In many airline accidents, the only devices that survive are the crash-survivable memory units (CSMUs) of the flight data recorders and cockpit voice recorders. Typically, the rest of the recorders' chassis and inner components are mangled. The CSMU is a large cylinder that bolts onto the flat portion of the recorder. This device is engineered to withstand extreme heat, violent crashes and tons of pressure.
The CSMU use three layers of materials for protection. The three layers, starting from the inside out are:
To ensure the quality and survivability of lack boxes, manufacturers thoroughly test the CSMUs, only the CSMU has to survive a crash -- if accident investigators have that, they can retrieve the information they need.
Here are some of the tests that make up the crash-survival sequence:
People have asked me……. Why don’t they make the airplane out of the same material that the Black Box is made? That’s a good question to be answered in another article.
During the fire test, the memory interface cable that attaches the memory boards to the circuit board is burned away. After the unit cools down, researchers take it apart and pull the memory module out. They restack the memory boards, install a new memory interface cable and attach the unit to a readout system to verify that all of the preloaded data is accounted for.
Refill your coffee cup, sit back and relax and let me tell you all about the infamous Black Box. Dig in and hold on, this may get a little long winded.
With any airplane crash, there are many unanswered questions as to what brought the plane down. Investigators turn to the airplane's Black Boxes – the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) for answers. Data from both the CVR and FDR is stored on stacked memory boards inside the crash-survivable memory unit (CSMU).
After an airplane accident in the United States, safety investigators from the National Transportation Safety Board (NTSB) immediately begin searching for the aircraft's Black Boxes. These recording devices, which cost between $10,000 and $15,000 each, reveal details of the events immediately preceding the accident. Honeywell and by L-3 Communications are two companies that manufacture the Black Box.
Dr David Warren of the Aeronautical Research Laboratories in Melbourne, Australia invented the "Black Box" flight data recorder. He was the first person to conceive of the idea of recording the flight crew's conversation on an airplane and of protecting that recording in the event of a crash or fire. The purpose of the Black Box was to help identify the reasons for a plane crash, by recording any clues in the flight crew's conversation. The Black Box was invented in 1953 and in production by 1957. The first ones were painted bright red or orange to make them easier to find after a crash. The origin of the term “Black Box” is uncertain. In 1960, Australia became the first country to make flight recorders mandatory in aircraft.
Flight Data Recorders
The (FDR) is designed to record the operating data from the plane's systems.The memory boards have enough digital storage space to accommodate two hours of audio data for CVRs and 25 hours of flight data for FDRs.
On July 17, 1997, the FAA issued a Code of Federal Regulations that requires the recording of at least 88 parameters on aircraft manufactured after August 19, 2002.
Airplanes are equipped with sensors that gather data. There are sensors that detect acceleration, airspeed, altitude, flap settings, outside temperature, cabin temperature and pressure, engine performance and much more. Solid-State recorders can track more than 700 parameters in large aircraft.
All of the data collected by the airplane's sensors is sent to the Flight-Data Acquisition Unit (FDAU) at the front of the aircraft. This device often is found in the electronic equipment bay under the cockpit. The FDAU is the middle manager of the entire data-recording process. It takes the information from the sensors and sends it on to the Black Boxes.
Cockpit Voice Recorders
In most commercial aircraft, there are several microphones built into the cockpit to track the conversations of the flight crew. There may be up to four microphones in the plane's cockpit, each connected to the cockpit voice recorder (CVR).
Any sounds in the cockpit are picked up by these microphones and sent to the CVR, where the recordings are digitized and stored. Position of the four microphones are:
Most magnetic-tape CVRs store the last 30 minutes of sound. They use a continuous loop of tape that completes a cycle every 30 minutes. As new material is recorded, the oldest material is replaced. CVRs that used solid-state storage can record two hours of audio.
Black boxes are usually sold directly to and installed by the airplane manufacturers. Both black boxes are installed in the tail of the plane. Putting them in the back of the aircraft increases their chances of survival. The precise location of the recorders depends on the individual plane. Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.
Typically, the tail of the aircraft is the last portion of the aircraft to impact the ground. The whole front portion of the airplane provides a crush zone, which assists in the deceleration of tail components, including the recorders, and enhances the likelihood that the crash-protected memory of the recorder will survive.
After a Crash
Although they are called "black boxes," aviation recorders are actually painted bright orange. This distinct color along with the strips of reflective tape attached to the recorders' exteriors help investigators locate the black boxes following an accident. These are especially helpful when a plane lands in the water.
Underwater Locator Beacon
If a plane crashes into the water, this beacon sends out an ultrasonic pulse that cannot be heard by human ears but is readily detectable by sonar and acoustical locating equipment.
This is the crucial item the accident investigation team was trying to find with the Air France Flight 447 flight from Rio de Janeiro, Brazil to Paris, France on 1 June 2009 that crashed into the Atlantic Ocean killing all 216 passengers and 12 crew members.
There is a submergence sensor on the side of the beacon that looks like a bull's-eye. When water touches this sensor, it activates the beacon.
The beacon sends out pulses at 37.5 kilohertz (kHz) and can transmit sound as deep as 14,000 feet (4,267 m). Once the beacon begins "pinging," it pings once per second for 30 days.
In the United States, when investigators locate a black box it is transported to the computer labs at the National Transportation Safety Board (NTSB). Special care is taken in transporting these devices in order to avoid any (further) damage to the recording medium. In cases of water accidents, recorders are placed in a cooler of water to keep them from drying out.
This process attempts to do is preserve the state of the recorder until they have it in a location where it can all be properly handled. Keeping the recorder in a bucket of water or cooler keeps it in the same environment from which it was retrieved until it gets to a place where it can be adequately disassembled.
After finding the black boxes, investigators take the recorders to a lab where they can download the data from the recorders and attempt to recreate the events of the accident. This process can take weeks or months to complete.
If the FDR is not damaged, investigators can simply play it back on the recorder by connecting it to a readout system. With solid-state recorders, investigators can extract stored data in a matter of minutes. Very often, recorders retrieved from wreckage are dented or burned. In these cases, the memory boards are removed, cleaned up and a new memory interface cable is installed. Then the memory board is connected to a working recorder. This recorder has special software to facilitate the retrieval of data without the possibility of overwriting any of it.
A team of experts is usually brought in to interpret the recordings stored on a CVR. This group typically includes a representative from the airline, a representative from the airplane manufacturer, an NTSB transportation-safety specialist and an NTSB air-safety investigator. This group may also include a language specialist from the Federal Bureau of Investigation and, if needed, an interpreter. This board attempts to interpret 30 minutes of words and sounds recorded by the CVR. This can be a painstaking process and may take weeks to complete.
Both the FDR and CVR are invaluable tools for any aircraft investigation. These are often the lone survivors of airplane accidents, and as such provide important clues to the cause that would be impossible to obtain any other way.
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