This is the Sound in the Cockpit Recorded in the CVR of Sriwijaya Air SJ-182 Before it Crashed into the Thousand Islands

Dream - The pilot's voice was not recorded by the Cockpit Voice Recorder (CVR) of Sriwijaya Air SJ182, which crashed near the Thousand Islands on January 9, 2021. As a result, the National Transportation Safety Committee (KNKT) lacks information about the cockpit conversation during the aircraft's malfunction.

"Coincidentally, from the cockpit voice recorder that we found, we discovered that the captain's voice was not recorded," said the Chairman of the KNKT Investigation Sub-Committee, Nurcahyo Utomo, as quoted from merdeka.com, Thursday, November 3, 2022.

The KNKT cannot determine why the pilot's voice of the aircraft flying from Soekarno-Hatta Airport to Pontianak, West Kalimantan, was not recorded. "However, there is a suspicion that the captain did not use a headset," said Nurcahyo.

According to Nurcahyo, the microphone in the cockpit also did not record any sound. It is suspected that it was due to the noise being blocked, so the conversation between the pilots could not be heard.

"Then there is a microphone inside the cockpit that we expected to record any sound in the cockpit, but it turns out that this channel is blocked by 400 hertz noise, so the conversation cannot be recorded," said Nurcahyo.

That is why the KNKT cannot analyze the cooperation in the cockpit. Only the co-pilot's voice and the air traffic controller's voice can be heard.

"So from this cockpit voice recorder, we cannot analyze how the cooperation in the cockpit was, what commands the captain gave to the co-pilot. However, we can hear the co-pilot's voice all the time, we can also hear the air traffic controller's voice," explained Nurcahyo.

Revealed, This is the Cause of the Sriwijaya Air SJ-182 Aircraft with 62 People on Board Crashing into the Thousand Islands

Dream - The cause of the Sriwijaya Air SJ182 plane crash on the Jakarta-Pontianak route near Laki Island, Thousand Islands, on Saturday, January 9, 2021, has finally been revealed.

According to the National Transportation Safety Committee (KNKT) team, based on Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data, there was a disturbance in the mechanical system of the Boeing 737-500 aircraft with registration PK-CLC.

"During the climb, there was a change in autopilot mode, which previously used the computer, to using the control panel mode," said the Chairman of the KNKT Accident Investigation Sub-Committee, Nurcahyo Utomo, in a Hearing with the DPR Commission V in Jakarta, Thursday, November 3, 2022.

In normal operation, according to Nurcahyo, the auto-throttle will move both thrust levers backward to reduce engine power. But in that flight, the auto-throttle could not move the right thrust lever.

After examining seven aircraft components, the KNKT confirmed that there was a mechanical disturbance in the aircraft, not in the computer system.

"Because of the density of flights that day and coincidentally there was another aircraft with the same destination, SJY182 flight was asked by the Air Traffic Controller (ATC) to stop at an altitude of 11,000 feet," he said.

As the aircraft approached 11,000 feet, Nurcahyo added, the engine power decreased because the right thrust lever did not move, causing a greater difference in engine power between the left and right sides, or known as asymmetry.

According to Nurcahyo, asymmetry creates a difference in engine power that generates a force that turns the aircraft to the left. The force to the left becomes greater than the force to the right by the aileron and flight spoiler, causing the aircraft to turn to the left.

Furthermore, the delay of the Cruise Thrust Split Monitor (CTSM) in disconnecting the auto-throttle during asymmetry because the flight spoiler provides a lower value resulted in increasing asymmetry.

"The lack of monitoring on the instruments and the tilted position of the control column may have led to the assumption that the aircraft was tilted, so the recovery action was not appropriate. This recovery could not be carried out effectively and in a timely manner," he said.

The aircraft carried 62 people, consisting of 12 crew members, 40 adult passengers, 7 children, and 3 infants.

Nurcahyo added that the investigation process is led by the KNKT and carried out in accordance with the International Civil Aviation Organization (ICAO) regulations, involving the aircraft manufacturer country, Boeing from the United States, the Singapore Transport Safety Investigation Bureau, the UK Air Accident Investigation Branch, and the General Electric engine factory. (Liputan6.com)