What you need to know about black boxes

How much data can a black box store?

A flight data recorder is required to store a minimum of 25 hours of flight information. A cockpit voice recorder is required to record a minimum of 2 hours of audio information.

How strong are they?

For the black boxes to survive a crash, they are built to be waterproof, fireproof, shockproof, heat and pressure and corrosion resistant.

The black box must be able to withstand an acceleration of 3,400 Gs (3,400 times the force of gravity), which equals an impact velocity of about 500 km/h. It must also survive flames up to 1,100 degrees Celsius for one hour, and the beacon should be able to emit a signal once per second while submersed in 6,000 meters of saltwater for at least 30 days.

How is data from black boxes retrieved?

It needs special technique to physically restore the black boxes. Investigators may need to clean and vacuum dry the black boxes and download data from them.