As investigators set to work unpicking the cause of Sunday’s devastating plane crash in South Korea, the black boxes carried on the aircraft will be of prime importance, with retrieval of data from the cockpit voice recorder under way.
All but two of the 181 people onboard died in the disaster, with the victims aged from three to 78. The Korean airline’s chief executive, Kim E-bae, said he wanted “to bow my head and apologise”, according to a statement on the company’s website, adding it was “difficult to determine the cause of the accident”.
Experts will hope the flight recorders offer crucial insights. Often called black boxes despite being orange in colour, these shoebox-sized electronic devices are often found at the rear of an aircraft to minimise damage in the case of a crash. However, while the devices are built to withstand extreme temperatures and underwater immersion, they are not immune to the effects of a crash.
The devices store flight data such as speed, altitude and fuel levels, as well as voice recordings from the cockpit and other sounds including engine noise and radio transmissions. In some aircraft, both types of data are stored in the same device, while in others the data is stored in two separate devices, as appears to be the case for Jeju Air’s flight 7C2216.
With both devices having been reported as discovered, they could provide vital clues as to how the Boeing 737-800 aircraft ended up skidding along a runway and colliding with an antenna array.
However, reports in South Korean media suggest the flight data recorder is partially damaged, potentially delaying its analysis, with officials saying that decoding it could take a month or more. According to the Yonhap news agency, the second black box containing the cockpit voice recorder was in better condition.
Among key questions are why the plane stopped broadcasting automated tracking data shortly before it hit the runway, why the plane’s landing gear failed to deploy as it prepared to land, and whether the crash could have been down to a bird strike, given air traffic controllers had issued a warning about just such a hazard as the plane approached the runway.
It has already emerged that the aircraft aborted its first attempt at landing and issued a distress call before its second, while video footage suggests flaps on the wings were not deployed to slow the aircraft.
Flight recorders have proved crucial to solving such conundrums before: among other examples, it was the retrieval of the black boxes from deep beneath the waves that allowed experts to finally piece together what happened to Air France flight 447 – an Airbus A330 that crashed into the Atlantic in June 2009, killing all onboard. The final report concluded that the plane crashed after a catastrophic series of events that began with the failure of speed sensors and led to the pilots pulling the aircraft up to 37,500ft to slow it down, resulting in the aircraft stalling.
According to the Korea Times, Joo Jong-wan, the director of aviation policy at the transport ministry, said at a briefing on Monday that the damaged flight data recorder would be transported to Gimpo airport the following day so that experts could assess the extent of the harm and determine how much data could be extracted.
Frank E Turney, the chair of the aviation department for Capitol Technology University in the US, said that while the black boxes could be helpful in an investigation, they were only part of the puzzle.
“The [black] box or the flight data recorder is not going to sit there and tell you this is what caused this accident. What it’s going to do, it’s going to give you all of the underlying factual data that you can use to try to assess how the accident occurred,” he said.
“Sometimes the data that you’re getting from the flight data recorder will be very conclusive on what the cause of the accident was, but most of the time it is going to be a piece of the overall investigation, and not necessarily a slam dunk on ‘this is what caused this accident’.”
One important point, he added, was that it was often not a single thing that caused an accident but a series of steps – known as the “accident chain” – that can include an initial problem, subsequent developments, and the response of the pilots.
Turney said investigators would explore many other avenues to understand a crash, including the structure of the plane, whether there was a mechanical error, and factors relating to the pilots – such as whether they had had enough sleep or were adequately trained.
“They’re going to go through all of that, and then at some point they’re going to sit down and go through all of this information to figure it out,” he said. “But the flight data recorder is usually a fairly sizeable piece of the puzzle that they use to determine the accident.”
Aviation experts have already raised safety questions over the placement of a concrete embankment 250 metres beyond the end of the runway at Muan international airport, into which the plane crashed before bursting into a fireball.
While the investigation continues, South Korea has launched an emergency safety inspection of the country’s entire airline operations, including a separate check of all Boeing 737-800s.
