How does an aeroplane’s ‘black box’ work?

After doing a little research, I can now tell you (basically) everything you ever wanted to know about black boxes…

In the average commercial aircraft, you’ll find the presence of multiple (usually four) microphones in the cockpit at any given time. They are located in the pilot and co-pilot’s headsets, as well as in the cockpit itself. Not only do these microphones record conversations between the pilots and cabin crew, they also record any ambient noise (such as switches being thrown or sounds generated by technical issues). The microphones all connect to the cockpit voice recorder (CVR), a master unit that stores the last 30 minutes of sound. The tape operates on a loop, essentially erasing itself every half hour. Continue reading