Indonesian authorities successfully downloaded the cockpit voice recorder (CVR) of Sriwijaya Air flight SJ-182 that crashed in January.
It took two and a half months to find, and then a bit under two weeks to secure and download successfully. But now authorities have it: they downloaded the CVR (cockpit voice recorder) of the Sriwijaya Air Boeing 737-500. Finding this recorder proved particularly challenging, because it separated from its pinger/locator beacon. Rescuers recovered this pinger in the first few days after the crash, along with the flight data recorder (FDR). Mud in the seabed hid some of the aircraft’s parts, including the CVR.
The latest announcement came on Tuesday the 13th of April, from investigator Nurcahyo Utomo of Indonesia’s National Transportation Safety Committee (NTSC/KNKT). The downloaded CVR of the Sriwijaya 737 has four audio channels. The authorities explained:
“NTSC managed to download all 4 channels from CVR, but channel 4 on CVR was disrupted. However, based on the existing records, it has added important data for the investigation which results will be presented in the final report.“
Sriwijaya CVR Download And Processing
The NTSC will have to synchronise the Sriwijaya CVR data from all four of the downloaded channels. “Each [channel] has the last two hours, including the record of the flight that crashed”, said Nurcahyo Utomo. The accident flight only lasted about 5 minutes, after the aircraft took off from Jakarta International Airport (WIII).
The aircraft was a Boeing 737-500, with registration PK-CLC. After taking off from runway 25R in Jakarta, the aircraft turned north, in contact with ATC. About three minutes into the flight, with the aircraft passing 8,000 feet, the left engine lever started to roll back. Engine thrust reduced consistently with the lever. The highest altitude the aircraft reached was approximately 10,900 feet, while the left engine thrust continued its decrease.
By this time the aircraft had over 45 degrees of left bank, and its pitch was over 10 degrees nose down. This is when the autopilot disengaged. The downloaded Sriwijaya CVR is vital here, because at no point in the preliminary report is there any mention of pilot inputs. Therefore investigators need to understand how events unfolded from the crew’s perspective.
Investigators haven’t offered any information regarding the timeline of the final report. So it seems that it could take some time before learn more about the data in the Sriwijaya CVR that authorities downloaded. The preliminary report already analysed the sequence of events in great detail, using the FDR as a source. In other words, the FDR helped to answer the question of WHAT happened. Hopefully, the CVR will complete the picture, with “How?” and “Why?”