Black boxes are 'essential'

Despite bad weather, a massive hunt for the victims of the plane crash resumed on Friday, January 2, in the Java Sea, southwest of the island of Borneo, Indonesia. AirAsia Flight QZ8501 had lost contact with air traffic control on December 28, just after the pilots requested a change in course to avoid turbulence. On board the Airbus A320-200 - which was halfway through a two-hour flight from Indonesia's second-biggest city Surabaya to Singapore - were 162 people. Ten bodies and pieces of wreckage have so far been recovered.

The first proof of the crash emerged when debris was spotted in an area not far away from where the jetliner dropped off radar screens. As the cause of the crash remains unclear, an international search and recovery team is also scouring the sea for the aircraft's wreck as well as cockpit voice and flight data recorders, or black boxes, hoping to determine what brought the plane down. To this end, a French crash investigation team is expected to use sensitive underwater acoustic detection devices.

Gerry Soejatman, an independent Jakarta-based aviation analyst, says in a DW interview that there are various theories circulating as to what might have happened on board Flight QZ8501, ranging from structural failure to a repeat of Air France Flight 447 (which crashed in the Atlantic Ocean en route from Rio de Janeiro to Paris in 2009 after the plane went into an aerodynamic stall). In order to determine what caused the AirAsia flight crash, the jet's black boxes and parts of the fuselage must be retreived, he adds.

DW: What does the finding of debris tell us about what possibly happened to the plane?

Gerry Soejatman: There isn't much to go on as there have only been several pieces found. This is unlike the case of Air France 447 where a lot of pieces were found floating, and those pieces told a similar story on what happened, resulting in the ability to put together roughly what happened (a low forward speed with high vertical speed impact onto the water), and that was confirmed by the black boxes.

QZ8501 has too few pieces to tell anything with certainty. We only have a few loose items from the cabin, and two un-inflated emergency slides from the rear exit. It is beginning to show that the impact may be similar to Flight AF447, but it is still too early to say.

Both aircraft appeared to have just passed the worst of the weather when something happened. Both aircraft climbed relatively quickly and then fell out of the sky. That is where the similarities end. The major difference is that Air Asia 8501 ended up descending at much lower speed than Air France 447.

What could the location where the debris was found possibly indicate?

The location of some of the debris and bodies that were found is not far from the position where the aircraft was last seen on radar. This means that the aircraft did not get very far, pointing to a relatively significant descent rate at relatively slow forward speed.

What information do you have about the events leading up to plane's crash?

All we know is that the weather was quite bad but it is usual for this time of the year as it is monsoon season. The aircraft seems to have flown past several Cumulonimbus clouds, but the aircraft requested a heading change to avoid more weather ahead, and also a change in altitude to avoid turbulence. The aircraft did turn to the left, before its questionable climb.

Many analysts argue the plane's crash was most likely linked to bad weather. What is your view on this?

Air accidents are almost always caused by more than one factor. Weather is certainly going to be a factor in the list of causes of the accident, but whether or not it is going to be the primary factor or just a secondary or contributory to the accident, is still too early to say.

What are search and recovery teams set to do next?

The main wreckage hasn't been found, so they will continue to search, and pick up bodies and floating debris whenever they come across them. The dive team is going to go to the two most likely spots where the main wreckage could be. Once they identified the main wreckage, they would then recover bodies that may still be inside, and then look for the black boxes, and perhaps recover significant pieces of the wreckage for further analysis.

How difficult will recovery efforts be in these waters?

The sea in the area is shallow. The water is murky giving an average underwater visibility of only two meters, with some strong currents in some areas. This makes it difficult for the dive team. On the search effort, the use of sonar in shallow waters is difficult as it is "noisy." In addition, the shallowness means that your sonar coverage is relatively limited. This needs specialist locators to look for the black boxes' Underwater Locater Beacons that work in the frequency range near the beacon's sonar transmission frequency.

What information do you expect investigators to obtain from the flight data recorder?

There are various theories as to what might have happened, ranging from a repeat of Air France 447 to structural failure. But the black boxes will fill in the large gaps that we have at the moment and enable us to piece together what happened on board QZ8501. In addition to the black boxes, pieces of the wreckage are set be analyzed to understand the dynamics of the impact and see if there are evidence of structural failure early on in the accident.

How important will this information be in determining what brought down the plane?

It is essential. We need to know what can be learnt from the accident in order to prevent a repeat, and also provide some form of closure to the friends and relatives of those onboard. To me personally, anything that we can learn from this accident to improve safety, is valuable.

Gerry Soejatman is an independent aviation analyst based in Jakarta, Indonesia.