Black boxes are made to withstand severe conditions— but they’re not black, and they’re not even boxes!
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.’ All recorders undergo countless tests that include 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 carry a minimum 25 hours of flight data. It should also be able to withstand the pressure of being a mile under water for 30 days.
When Air France Flight 447 crashed into the Atlantic Ocean on 1 June 2009, all 228 passengers and the entire crew aboard were killed. Investigations were hampered because the aircraft's black boxes were not recovered from the ocean floor until May 2011 – nearly two years later.
Amazingly enough, the black boxes were still intact after such a long period of sea water and pressure exposure! The history of the flight as recorded by the black boxes revealed that the aircraft's crash into the sea was not a result of mechanical failure or severe weather conditions, but because the flight crew had raised the aircraft's nose, reducing it's speed until it stalled. They were unable to recover from the stall and crashed into the ocean.