cctv is melanie wilkes reports. this is the singing share of the black box one hopes about every second of every minute of every hour for as long as the batteries last. that's usually about thirty days there were two black boxes on board malaysia airlines flight three seventy one recording conversations and other sounds in the cockpit the other recording data is protected in shock mounted inside the flight data recorder information is displayed in a series of graphs. every flight data recorder recourse to a binary values it's a series of ones and zeros in order for humans to understand that we be converted into engineering units and engineering units simply mean feat for altitude your speed is recorded in dots. one graphic show whether someone deliberately caused the aircraft to change course and other like this one would show the plane's altitude. if an hd seventy suddenly drops to a lower altitude. the graph would show it. i think one important thing is that people will be looking at is who was in control of the a