IAF helicopter crash: How does Black Box work? Why is it not destroyed in a crash?

The Air Force officials on Thursday confirmed the recovery of the ‘black box’ of the ill-fated Russian-made Mi-17V5 chopper that was carrying Chief of Defence Staff General Bipin Rawat, his wife Dr Madhulika Rawat, and 11 members of his staff.

The flight data recorder, also known as the black box, was recovered from the IAF helicopter crash site. The black box has now been taken for investigation. The equipment is key in the investigation regarding the IAF chopper crash that killed CDS Bipin Rawat and 12 others.

What is black box?

Though called black box, the flight data recorder is a device painted in bright orange colour and it records all the important flight details, which can provide thorough information on what happened to the flight before it crashed. The bright color of black box in the aircraft makes it easy to spot amid debris.

The flight data recorder is a vital electronic device that records 88 vital parameters about a flight, including the airspeed, altitude, cockpit conversations, and air pressure during the flight. The equipment will be placed in every aircraft to help with the investigation in the event of a mishap.

How does a black box work?

The origin of the black box remains a mystery, although many historians attribute its creation to Australian scientist David Warren in the 1950s. The equipment has two recorders, a Cockpit Voice Recorder (CVR) for pilot voices or cockpit sounds, and a Flight Data Recorder (FDR) that records all the happenings during a flight.

Following its retrieval, trained technicians peel away protective material and carefully clean connections without accidentally erasing its data. The audio or data file will then be downloaded and copied, which is later decoded from raw files into graphs.

Once the recorder equipment is found, investigators prefer to work methodically and reach conclusions depending on the damage to the boxes and type of accident. Only the key investigating officer and a select few are allowed to look into the contents of the recorder during an investigation. Some cases take only hours to get minimal information, but several cases have seen investigations drag on for a year or more.

Why is a black box not destroyed in crash?

A black box weighs about 4.5 kg and contains four main parts including a chassis, an underwater locator beacon, a 'Crash Survivable Memory Unit'. The chassis or interface is designed to fix the device and facilitate recording and playback, while the underwater locator beacon helps with its spotting.

The core housing or the 'Crash Survivable Memory Unit' will contain finger-nail sized recording chips on circuit boards. These will be made of corrosion-resistant stainless steel or titanium in order to protect the interior components from impact, fire, and water. 

Meanwhile, the circuit board, also called memory board, is placed in an aluminium housing, as it is rust-resistant unlike alloys containing iron. The aluminium box is wrapped in a one-inch layer of insulation that withstands up to temperatures of 2,030 degrees Fahrenheit. The box is designed to take a large fall without major impacts too.

Image: PTI/ SHUTTERSTOCK