Missing Flight 370: How Do Black Boxes Work?

A possible break in the mystery of the missing Malaysia Airlines Flight 370 plane came when ships detected "pings" consistent with the aircraft's black box. But how does a black box actually work?
Black boxes, or flight recorders, are electronic devices that record information on an airplane to be used in the event of a severe incident such as a crash. Usually, an aircraft carries two types of recorders.
The first, a flight data recorder, makes a record of instructions sent to a plane's electronic systems; the second, a cockpit voice recorder, makes a record of conversations, radio communications and other sounds in the cockpit. Sometimes, the recorders are part of the same unit.

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