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Inside an aircraft’s 'black box' recorder

Phil Han, Special to
How do black boxes work?
How do black boxes work?

What exactly are a plane's black boxes and how do they work?

Aircraft manufacturers equip all their planes with two black boxes – a flight data recorder and cockpit voice recorder.

A flight data recorder tracks all the plane's critical information during flight – everything from altitude, air speed, pitch, fuel levels and temperature. Most data recorders are able to record up 25 hours-worth of information, which is plenty for all long-haul flights. Once 25 hours of data is recorded, it will simply loop onto itself and record over the existing data.

The other black box contains the cockpit voice recorder. This provides playback of everything the pilot, crew and air traffic controllers discuss. It also records critical alarm noises that may go off during a flight. Investigators can gain an insight into what happened in the final minutes before a plane crash by listening to these recordings.

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Despite being referred do as a black box, the devices are actually bright orange. These make it easier for search crews to locate the boxes in a crash. Both black boxes are capable of withstanding up to 3,400 G's worth of impact – or as much force as going from 112 kilometres an hour to zero in one second.