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The Hunt For Black Boxes
As the Mounties, the Japanese police and the Indian Central Bureau of Investigations pursued the criminal aspects of the twin tragedies, the foremost task facing accident investigators in the days following the Air India crash was to find the all important ‘black boxes’ from the 747. At the site of the crash, the depth of water was approximately 6,700 feet. Air India investigator H. S. Khola would call it a ‘very difficult and challenging job’. But it had to be done if any sense was to be made out of what had happened to the aircraft.
Time was running out day by day. The black boxes have enough power to transmit signals for approximately 30 days. Ten days after the plane had gone down, there was still no sign of a signal from the black boxes.
The boxes can provide vital clues. The Cockpit Voice Recorder contains an endless magnetic tape which records conversations from several mikes in the cockpit. It erases the tape and begins recording all over again every 30 minutes. What were the crew saying at the time of the crash? What was their reaction to the emergency? Did they have time to say anything at all? Only the voice recorder could answer these questions.
The Digital Flight Data Recorder was even more important. It keeps tabs on 52 different aspects of the flight, including aircraft heading, altitude, position of landing gears, the thrusts of the engines and the position of the rudder, among other things.
According to an official report by Khola, three ships were handed the task of first locating the boxes and then bringing hem to the surface. The Guardline Locator, a ship provided by the accident investigation authority of the United Kingdom, Le Aoife, an Irish naval vessel, and the Leon Thevenin, a French cable-laying ship chartered by the Indian Government, finally began picking up pings from the bottom of the ocean on 4 July. The pings were first picked up by the Guardline Locator. It could hear two separate sources of sounds. It gave the Leon Thevenin the location of the sound sources.
The French ship began searching the general area but did not have any success until 9 July. Then, using a cable and its underwater mini-submarine the Scarab, the vessel plucked one of the boxes from the deep. It was the Cockpit Voice Recorder. The next day, sonar picked up signals in the same area. Again, the miracle-working Scarab went to the bottom of the sea and plucked up the Data Recorder.
A major task had been accomplished. The trick now was to safely transport the two black boxes so that their valuable information could be analyzed. Both boxes, returned to shore on 12 July by the Leon Thevenin, were placed in watertight containers and shipped to India where they would be analyzed by a study group of experts.
In Bombay, the two devices were kept under armed police guard. In accordance with the orders of Judge Bhupinder Kirpal, appointed by the government of India to launch a judicial inquiry, the boxes were opened on 16 July in the presence of the US National Transportation Safety Board and the Canadian Aviation Safety Board, with Indian appointee Satendra Singh acting as group leader. The experts prepared readouts from the boxes and sound spectrum analysis was carried out at India’s top scientific institution, the Bhadha Atomic Research Centre in Bombay.
The experts were in for a surprise. Both the Cockpit Voice Recorder and the Data Recorder had stopped recording simultaneously at 7:14:01. The explosion had severed the power supply of both the devices, which are located near the aft luggage compartment just behind a passenger entry door.
Nevertheless, analysis of the Data Recorder would provide vital clues about the mechanical aspects of the flight and enable investigators to rule out other possible causes of the crash. The data would also confirm that Flight 182 dropped like a stone from the sky. There was no warning. No emergency declared. Nobody had a chance.
The experts made the following observations from their analysis of information from the two recorders:
Chief investigator Khola of Air India drew the following conclusions from the analysis of the ‘Black Box’ data:
‘From the correlation of the recordings of the Data Recorder and Cockpit Voice Recorder and the Air Traffic Control (Shannon) tape, it is observed that the beginning of the abnormal sounds recorded on ATC Tape (the split-second burst of microphone clicking picked up by Shannon as the plane disappeared from radar) coincides with the timing correlation further shows that the conversations in the cockpit were normal and there was neither any warning nor any emergency declared till the time the flight recorders stopped functioning.’
The Cockpit Voice Recorder taped the conversation between Captain Bhinder and Flight Purser Dinshaw. Bhinder was asking for that little bow who wanted to see the cockpit. In the final seconds prior to a bang being recorded, Flight Engineer Dara Dumasia was asking Bhinder to contact London Operations for seals to close up the bar aboard the aircraft for customs purposes. He was cut off in mid-sentence by the bang. At the same time, the Shannon ATC tape had recorded indecipherable sounds for a split-second.
Six experts – Dr S. N. Seshadri of the Bombay Atomic Research Centre, Satendra Singh of the Civil Aviation Department in Bombay, John Young and Paul Turner, the two US experts, and P. De Niverville a B. Caiger of the Canadian Aviation Safety Board reached this conclusion about the sounds recorded at Shannon:
‘It appears that the ATC recording contains the beginning of the aircraft breaking until power is lost to the transmitter since channel one and channel four (Captain’s and co-pilot’s mikes) appear to contain a transmitted signal on the Cockpit Voice Recorder.’
Paul Turner, an expert on Cockpit Voice Recorders, made this individual finding:
‘During my observations of numerous Cockpit Voice Recorders I have head and observed a number of aircraft breakages due to various causes. In this case, the explosive sound on the Cockpit Area Mike occurs prior any electrical disturbances observable on the selector panel signals. Electrical disturbances can generally be seen prior to audio signal when explosive sounds originate at any significant measurable distance from the microphone (15 feet) and in the area where there are significant electrical systems. It is my opinion that an explosive event occurred close to the cockpit.’
Turner added that ‘the cockpit area mike signal that follows the explosive event shows a very much higher noise level than cockpit ambient of 85 decibels, indicating to me that the cockpit area was penetrated and opened to the atmosphere. The selector panel signals show signatures similar to those of an aircraft breaking up and are apparently caused by electrical systems disturbance (circuit breaker blowing, fuse switching etc.).’
Turner concluded: ‘The lack of a Mayday call and the apparent inadvertent signal from the cockpit suggest crew incapacitation.’
In a nutshell, the observations pointed to one thing only. When the Cockpit Voice Recorder stopped functioning, an explosion had occurred on board the aircraft while it was cruising steadily at 31,000 feet with all of its functions normal. After that the plane was unable to sustain flight. It lost altitude broke up in mid-air and scattered bodies, bags and metal. The emergency had developed so fast that the crew had no time even to relay a distress call.