Black box may not solve entire mystery
CRASH OF FLIGHT MI 185
THE black box recovered from the wreckage of flight MI185 will provide vital clues on what happened before the SilkAir plane crashed last week, but it may not solve the entire mystery.
Past incidents have shown that the discovery of black boxes of planes that crashed sometimes may not bring investigators any closer to the truth.
The box found yesterday was the flight data recorder, which monitors critical instrument readings such as time, altitude, speed and direction of the aircraft.
The other black box, which is still missing, the cockpit voice recorder, records radio transmissions and sounds in the cockpit, such as pilots’ voices and engine noises.
Using this information, a computer-animated reconstruction of the flight can be made.
A pilot of more than 30 years told The Sunday Times: “You can tell what happened to the plane, but you cannot tell what caused it to happen that way.”
He said that the information from the flight data recorder acted like the “pulse” of the plane, monitoring all the vital signs of the plane and could show whether the aircraft had dived or exploded before impact.
“From there, you can gather what kinds of forces were acting on the aircraft before the last recording. More or less, you can reconstruct at least the last half an hour or so.”
He added: “Of course, it will reveal a lot of things, like what kinds of gravity forces the plane experienced. You can determine conclusively if it was a mid-air collision.”
Investigations could take up to months or years, he said, as investigators had to look at supporting evidence such as the spread of the wreckage.
Among the various cases in which black boxes have proven useful was in the 1994 American Eagle crash near Chicago.
The flight recorder had data on 120 different details of the flight, and helped investigators determine that ice coating the plane had led to the accident.
However, the amount of data captured by black boxes varies widely, depending on the age and model of the plane. Most record between 13 and 300 in-flight characteristics.
In an incident near Pittsburgh in 1994, a USAir Boeing 737 plane suddenly went out of control and crashed shortly before landing.
The crash remains unexplained although the black boxes were recovered. The data recorder on the USAir plane tracked only 13 aspects of the flight, known as parameters, which was insufficient for investigators in this case.
Still, yesterday’s find in Palembang was a triumph for the rescuers, who had feared that the search for the black boxes of the 10-month-old Boeing 737-300 might be a lost cause.
The divers have had to battle strong currents and zero visibility as they crawl on the river bed of the Musi to look for the wreckage.
The first three days yielded little, with only minor parts of the plane’s debris found at the bottom of the Musi and in surrounding mangrove swamps.
But the divers’ luck changed mid-week after Indonesian and Singapore search teams, using sophisticated sonar equipment, found parts of the black box casing in the 15m deep river.
It gave the authorities hope that the black boxes had not been swept away by the strong underwater currents.
Vice-Admiral Rosihan Arsyad, commander of the Indonesian navy’s western fleet, overseeing naval operations in the crash site, said:
“We knew we were on to something when we found the black box casing. That motivated us to step up operations for the flight and voice recorders.”
Rescue officials said that after the finding, navy divers narrowed down the area of their search of the box to around some 200 m from the western bank of the Musi.
The black box and its components were indeed found buried in silt in an area measuring 10 m by 10 m.
As an incentive to push them harder, Vice-Admiral Rosihan even offered his Breitling wristwatch to the divers. “It is a small reward,” he said.
He would probably have to give up the Breitling, but the price, he said, was nothing compared with the haul yesterday.