As we have already mentioned in previous publications, safety is a priority in aviation. Therefore, the investigation of any incident or accident is essential to develop protocols in order to achieve a reliability close to 100%.
The black box, also known as flight recorder, is a device designed to capture and store important data during flight. Inside, there are different electronic components, recording systems and sensors that register all kind of technical information about the aircraft’s performance such as speed, altitude, position, control settings, vibrations as well as cockpit conversations and sounds. All this allows investigators to reconstruct the events prior to an accident and determine its causes, so preventive measures that help to improve safety in the aeronautical industry can be taken.
The aircraft’s black box is a crucial device in the investigation of air accidents. It provides vital information to understand the actions and decisions taken by the crew during the flight, giving answer to many of the unknowns that may arise which will help to create new protocols of action and prevent future incidents in similar circumstances.
We speak of black boxes in the plural because the international air legislation requires two for commercial flights. These are two fully armored titanium and steel cases that store recordings on solid state discs. They weigh approximately 4.5 kilograms and are rectangular shaped.
Both record data that will be useful in subsequent investigations and may become conclusive. They provide vital information to reconstruct the sequence of events prior to an accident, so they often clarify how and why the misfortune occurred.
The black box consists of two main parts: the flight data recorder (FDR) and the cabin voice recorder (CVR):
The black box is designed to withstand extreme conditions such as high temperatures, impacts and water immersion. This ensures that the stored data is not lost in the event of an accident. Likewise, the black box is equipped with an emergency locator, which allows its quick location in case the aircraft crashes.
Despite its name, the black box of an aircraft is not black. Instead, it is painted in a bright and striking color, usually orange, to facilitate its location in the event of an accident.
The black box exact location may vary depending on the airplane design. Therefore, it is normally located at the rear of the aircraft, near the tail. This is because this area is usually less affected in case of an accident.
Airplane’s black boxes are real technological wonders. The amount of information they may collect and the resistance they have to protect this data is staggering.
A modern Flight Data Recorder (FDR) can record up to 25 hours of flight data. This includes more than 700 different parameters, from the aircraft’s speed, altitude and course to the setting of flaps and engine pressure. Specific details such as the joystick position, landing gear configuration, engine oil temperature, and even the angle of the ailerons are also recorded.
On the other hand, the Cockpit Voice Recorder (CVR) can record the last two hours of everything you can hear in cockpits. This includes communications between pilots, conversations with air traffic control, any alarm or warning sounds as well as any other ambient noise that may provide valuable information in an accident investigation.
As for Data Protection and Storage, the heart of a black box is the Crash-Survivable Memory Unit (CSMU) where all data is stored. These are recorded on solid memory chips, much more resistant to damage than old memory disks.
CSMU is designed to withstand extreme conditions and is enclosed in a stainless steel or titanium case coated with thermal insulation to protect it from the intense heat that could be generated during an accident. Likewise, this cover is designed to withstand an impact equivalent to a fall of 3,400 meters, a pressure of 5,000 psi and temperatures of up to 1,100 degrees Celsius during an hour.
Black boxes have evolved considerably since their invention. Recent advances include the addition of image data recording that may capture information from cockpit displays and other visual systems. This can be especially useful to know exactly what pilots were seeing right before an accident.
When a plane crash occurs, the recovery of black boxes is a top priority for investigators. This process can be quite a challenge depending on the accident circumstances: location, environmental conditions and magnitude.
For their location, the boxes themselves have a system whereby they emit an ultrasonic signal, at least for 30 days, either underwater or in mountainous areas. At present, some aircrafts are equipped with a black box deployment system which, in the event of an accident on water, they automatically separate from the aircraft and float on the surface facilitating its recovery.
Once located, they should be recovered with great care to avoid further damages. In accidents where aircraft’s debris is submerged, the use of diving equipment or remotely operated vehicles may be required.
Recovered black boxes are safely stored and transported to specialized laboratories where experts will download the recorded data for its analysis. This process can be very complex and take weeks or even months before getting to a definitive conclusion.
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