In science, computing, and engineering, a black box is a device, system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). Almost anything might be referred to as a black box: a transistor, algorithm, or the human brain.

The opposite of a black box is a system where the inner components or logic are available for inspection, which is most commonly referred to as a white box (sometimes also known as a "clear box" or a "glass box").

What is a Black Box?

Often one of the first pieces of techno-speak that springs to mind when we hear of an aviation disaster - and a catch-all phrase popular with the media - is ‘Black Box,’ but how much do you really know about these vital pieces of equipment?

Any commercial aeroplane or corporate jet is required to be equipped with a cockpit voice recorder and a flight data recorder. It is these two items of separate equipment which we commonly refer to as a ‘Black Box.’ While they do nothing to help the plane when it is in the air, both these pieces of equipment are vitally important should the plane crash, as they help crash investigators find out what happened just before the crash.

Often, for example when a plane crashes into the sea, as happened with the 1985 bombing of Air India flight 182 by Sikh terrorists over the Atlantic Ocean just west of Ireland, investigators have very little to go on – on this specific occasion the plane crashed before the pilot could even issue a mayday signal and much of the debris sank into the sea, leaving few clues.

Today, the Black Box is still just as vitally important in helping piece together the causes of a plane crash, as seen by the discovery of the Black Box in the Mexico plane crash that killed fourteen, including the interior minister of Mexico on 4th November, 2008.

To help locate the cockpit voice recorder and a flight data recorder in the aftermath of a plane crash that occurs at sea, each recorder has a device fitted to it known as an Underwater Locator Beacon (ULB). The device is activated as soon as the recorder comes into contact with water and it can transmit from a depth as deep as 14,000 feet. Also, to help investigators find them; a Black Box is not actually black at all, but bright orange.

All recorders undergo countless tests. For example, one Black Box recorder, the L-3 FA 2100 underwent testing that includes exposure to a 1,110°C fire for an hour and 260°C heat for 10 hours. It is also able to operate between -55° to +70°C and it can carries a minimum 25 hours of flight data.