New Delhi, June 25 -- Every aircraft is fitted with a "black box", a device that tracks key attributes of a flight. The black boxes mounted on board commercial flights comprise two devices. The first is the flight data recorder, or FDR, which records these attributes or "parameters", including a flight's time and altitude for the total duration of a journey. The second is the cockpit voice recorder, or CVR. It records all sounds made in the cockpit, including what the pilots and the flight crew say, besides sounds made by equipment. The black boxes store their data in memory chips and can withstand extreme heat and water depths.

India's Aircraft Accident Investigation Bureau (AAIB), reporting to the ministry of civil aviation, has starte...