Inside The Black Box

After any aviation disaster, it's a race against time to find survivors, locate wreckage and retrieve black boxes - the flight data and cockpit voice recorders. Avionics engineer Rajiv Trivedi explains how they work.

Investigators have recently ruled out the involvement of terrorists in the crash of the AirAsia Flight QZ8501. This information was revealed after the analysis of the plane's flight data and voice data recorders last week. The audio recordings from the voice data recorders contain no sounds of gunfire or explosions. Sirens were “screaming” in the background as pilots talked among each other. The sirens indicated a stall that the pilots were frantically trying to stabilize.

Like Air Asia flight QZ8501, the cause of many air crashes have been explained with the data provided by the black box. In the case of Air France flight 447 that was flying from Rio to Paris in 2010, the black boxes revealed that pilot error led to the crash, killing all 228 people on board.

The black box actually refers to two devices, a cockpit voice recorder and a flight data recorder. It is mandatory for every aircraft to have these devices. Australia was the first country to make flight recorders mandatory in aircrafts in 1960. In India, the Directorate General of Civil Aviation (DGCA) made it mandatory for all aircrafts, including helicopters, to carry a CVR and FDR for recording digital communications with Air Traffic Service (ATS) from January 1, 2005.

“Soon, the need for retrieving the black boxes from under the water will fade with the advent of latest technology. Information available from data streaming might help better pinpoint search and rescue and recovery efforts,” he says.

The black box is orange in colour with glow strips to make them easier to locate. These electronic devices have “pingers” that emit signals that can be heard more than a mile away but, the batteries just last for about a month. So, investigators need to find the box within a certain period of time and it can take up to few months to reach to analyze the data and come to informed conclusions about what caused a flight to crash.

Avionics Engineer Rajiv Trivedi describes the evolution and future of black boxes. “Soon, the need for retrieving the black boxes from under the water will fade with the advent of latest technology. Information available from data streaming might help better pinpoint search and rescue and recovery efforts,” he says.