We have often heard the term ‘black box’ while watching episodes of Air Crash Investigation on NatGeo or Discovery Channel. After an air crash, the officials tend to search for the Black Box in the remains of the crash. So why is there a need to searching a black box? What does it contain?
A Black Box consists of two components – a flight data recorder (FDR) and a cockpit voice recorder (CVR).
There is another important device in the black box- the Flight Data acquisition unit (FDAU). This device is found in the cockpit. This unit intakes information from all the sensors and sends to FDR and CVR.
FDR records all the measurement and functions of the plane that occurs during the flight like speed, altitude, heading and other important information. In addition, because of advancement in the FDR technology, the recorders also record the experience of turbulence – a small change in the flight pattern and wing flap movement. These data help to create the realistic crash simulation.
The second component CVR also provides crucial information. It records all the communication and dialogue between the crew members and an audio recording of the cockpit. This device helps the trained investigators to listen to the precise audio recordings for unusual noises, alarms, and ambient noise changes.
In the peril moments, the CVR records the audio input from 3-4 microphones that are strategically placed in the pilot’s helmet and cockpit. Generally, only last 30 minutes of the audio is recorded before a crash. To avoid replacing the memory storage of the black box after every flight, the recorders began taping over the old data during normal flight.
Both FDR and CVR provide a wide range of information before the plane crash including when, where and why it occurred. Using these datasets, investigators try to figure out the reason of crash.
How does a Black Box sustain crash?
The black box is designed in such a way that it survives the crash and can be recovered easily. The outer shell is made from titanium to subdue pressure, the second layer provides insulations and the inner layer is made of fire and heat resistant material.
The black box is tested under extreme conditions and some of them can withstand a 2000-degree fire and water pressure at up to 14000 feet. The solid-state memory board that records the information in this device contains no moving parts, therefore there is no harm to the recordings.
Sometimes it can be hard to discover the black box, specifically in the cases of a deep ocean crash site. For that, the black box has underwater locator beacon that starts pinging its location on coming with contact to water. The black box is orange in color which makes it easier to spot.
The recording devices are made to survive extreme forces so that it can provide the crucial information to improve flight safety.