Indonesian divers are searching for the remains of most of the 62 victims of the Boeing 737-500, which plunged into the waters off the capital Jakarta just four minutes after taking off on January 9. They have recovered one of the plane’s so-called black boxes, the flight data recorder (FDR), but the potentially crucial cockpit voice recorder (CVR) is still missing.
Making the search more complicated, the remaining box has stopped emitting pings. The Java Sea is relatively shallow compared with the Indian Ocean on the opposite side of Java. The shallower water depth helped search teams locate the wreckage the day after the crash and for divers to comb through the wreckage, unlike crashes in deeper water where there’s a heavier reliance on machinery.
Nurcahyo Utomo, an investigator at Indonesia’s National Transportation Safety Committee (KNKT), said the jet may have been intact before it hit the water, given the debris appeared to have scattered in a relatively tight area underwater.
The search team had narrowed down the suspected location of the “black box” flight recorders and a remote-controlled vehicle would help scour the sea bed, navy chief of staff Yudo Margono said.
“There is so much debris down there and we have only lifted a few pieces. Hopefully, as we take out more they (the recorders) can be found,” Yudo told reporters aboard a ship.
The Remotely Operated Vehicle (ROV) in conjunction with human divers, and naval ships with sonar, are being used to locate, raise, and identify debris and bodies from the wreckage.
The debris sits in water anywhere from 15 to 25 metres deep, a tiny fraction of other depths at which black boxes have been recovered. The Lion Air crash in 2018 was in similar waters of Jakarta but the AirAsia crash in 2014 was much further out in the Java Sea. However, the water was still only marginally deeper. When compared to other open ocean crashes such as the Air France AF447 disaster in 2009 the difference in scale of the recovery tasks are more apparent.
The scale of recovery
Here are a selection of plane crashes at sea, illustrating the range of depths at which black boxes have been recovered.
An earlier version of this story mistakenly showed the JT610 crash as occurring in 2014. This has been corrected since it crashed in 2018.
Simon Scarr and Marco Hernandez
Bathymetry data from GEBCO 2019 grid
National Oceanic and Atmospheric Administration (NOAA)
Indonesia’s National Search and Rescue Agency (BASARNAS)
Matthew Tostevin and Michael Perry