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The Purpose of a Black Box in Airplanes

Vrinda Varnekar Mar 17, 2019
Post the very tragic and mysterious disappearance of the MH370 Malaysia Airways flight, we often heard or read the term 'black box' mentioned in various media outlets. ScienceStruck finds out more about what the box is, how it works, and why it is necessary.

Indestructible Black Box

The black box on-board Air France flight 447 was found intact nearly two years after the airplane had crashed into the Atlantic Ocean in 2009. It gave quite significant clues as to how the accident had happened.
From the time of its inception to now, a black box is one of the most important accessories of an airplane, one which must be on-board, no matter what. Though it wasn't really taken seriously when it was first invented, it soon took the world by storm, and today, every airplane is equipped with it.
First invented by Dr. David Warren in Australia, a black box became an obligatory piece of equipment for every aircraft in Australia post a mysterious airplane crash in 1960.

A black box, technically known as a Flight Recorder, is the main and the most important source of information in case of an airplane crash with no survivors.

What is a Black Box?

A black box, or a Flight Recorder, comprises two separate and equally vital pieces of equipment―the Flight Data Recorder and the Cockpit Voice Recorder.
The black box helps air crash investigators determine the details of aviation accidents―whether it was negligence on the crew's part or a problem with the aircraft, or anything else. It also helps in understanding the series of events that led to an accident.
The Cockpit Voice Recorder is an audio recorder that registers more than just the pilots' voices, it records the total and complete audio environment of the cockpit. The Cockpit Voice Recorder (CVR) helps trained investigators determine the nature and causes of an accident through engine noise, airflow noise, stall warnings, emergency pings, etc.
Investigators can then also determine the speed of the aircraft through this information. A Cockpit Voice Recorder is hence very important for investigators after an airplane accident. The CVR must hold at least 2 hours of audio material.
The Flight Data Recorder records several important functions of an aircraft at the same time, such as the time of flight, the speed, altitude, the direction of the aircraft, etc. This data is invaluable for investigators as it helps them exactly determine the cause(s) of an aviation accident.
The modern Flight Data Recorders even aid investigators to create a visualization of what must have happened, when, and how. These two individual pieces of equipment together make up the black box.
Without the black box, it is almost impossible to find out the cause of an aviation accident, especially mysterious ones with no survivors. The black box itself is indestructible, and remains intact for a long, long time after an accident. It is equipped with an underwater beacon that generates 'pings' which helps search parties find it quicker.

Description and Location of a Black Box

Though the Flight Recorder is commonly known as the black box, in reality, it is far from the color of its name. In fact, it is bright orange in color, so as to make it easy to distinguish it from debris in an accident. It has minimal width and height, and weighs a little lesser than 50 pounds.
The black box is fitted with an underwater locator beacon which is activated the moment the black box comes in contact with water. It then begins to generate 'pings' which help search parties locate it underwater.
The black box is generally placed at the tail of the aircraft, as the tail is the last part of the airplane to face impact in an accident, thus enabling it to record maximum information and face minimum damage.

How Does a Black Box Survive a Crash?

A black box is made to undergo several intense survival tests before it can be used. These tests expose the black box to extreme conditions and pressure, similar to what it would be exposed to in case of an accident.
A black box is enveloped in corrosion-resistant material so that it stays intact underwater for a long time, even years. The black box of Air France 447 was found intact nearly two years after its accident in 2009, thanks to the fact that it was made corrosion-resistant.
The design of a black box is such that it can withstand an acceleration that is 3400 times the force of gravity, and an impact velocity of about 310 miles per hour. Additionally, it can also withstand extreme temperatures of up to 2000°F, and -67°F during a crash.
These survival tests consist of the same or more impact that would be felt during an actual accident. A black box must be able to record about 25 hours of flight data.
A Flight Recorder can survive underwater, even if it is lost in the water body due to currents. Since the black box is equipped with an underwater locator beacon, it makes it easier for search parties to locate it in expansive waters.
The beacon generates 'pings' at the speed of one ping per second, and keeps doing so for 30 days at a stretch. This gives search parties enough time to locate the black box, even if it is far away from the wreckage.
A black box is not only essential to try to piece together how and why an aviation accident happened, but is also extremely important for taking appropriate safety measures so that such airplane tragedies don't repeat themselves in future.