Defence officials on Thursday retrieved the Flight Recorder, more popularly known as 'Black Box', of the ill-fated Indian Air Force helicopter that crashed near here on Wednesday. Chief of Defence Staff, General Bipin Rawat and 12 others were killed in the incident.
Official sources said the black box was retrieved in the wake of authorities expanding the search area from 300 metres to one km from the accident spot.
The black box would provide crucial data on the chain of events leading to the tragedy on the hills on Wednesday when the 63-year old Rawat, the country's first CDS, his wife and 11 others were killed when the Mi-17VH helicopter they were travelling in crashed and went up in flames, leaving only one survivor.
Rawat was on his way to the Defence Services Staff College (DSSC), Wellington to address the faculty and student officers of the staff course when the fatal mishap happened in the Katteri-Nanchappanchathram area.
WHAT IS A BLACK BOX?
A black box is a compressor-shaped device that is painted in a high-visibility orange colour, which is installed in aircraft to help investigations in case of accidents. Somewhat like a hard disk, the black box is a highly protective device that records all the data of the flight and conversations in the cockpit. Besides taping cockpit conversations, the recorder also carries data on automatic computer announcements, discussions with the crew, radio traffic and announcements to the passengers.
According to experts, the flight recorder also stores private conversations between the pilots, so that it can provide key details during an investigation with regards to the developments leading up to an accident.
There are two types of flight recording devices:
The Flight Data Recorder (FDR) that stores all the recent information of the flight through the recording of dozens of parameters collected multiple times per second and the Cockpit Voice Recorder (CVR) that records cockpit sound along with conversations between the pilots.
ORANGE IN COLOUR:
The black box these days are painted bright orange colour, which makes it highly visible and thus easier to spot in the wreckage of the crash. So why is it called a 'Black Box?' The answer is simple, when these recorders were first introduced, they were black in colour and hence stuck with the name. The device is double wrapped in a corrosion-resistant stainless-steel container with high-temperature insulation, which is designed to withstand the harshest of crashes, either on the land and over the seas.
CAN BE RECOVERED FROM UNDERWATER:
While crashes can take place anywhere both on land and over seas, the flight recorder is built in a way that it can be recovered from seas as well. It sends out a signal on contact with saltwater that can be picked up within a radius of about two kilometres. The black box can also withstand water pressure found in depths of up to 6,000 meters.
With Inputs from PTI & Agencies