It has been revealed that the flight data recorder (FDR) and cockpit voice recorder (CVR), both black boxes of the Jeju Air aircraft, failed to save records during the last 4 minutes before the collision. Aviation experts analyzed that the aircraft's engines likely malfunctioned after colliding with a bird, resulting in a power shutdown state that interrupted the recording.
The Ministry of Land, Infrastructure and Transport's Aviation Railway Accident Investigation Committee (ARAIC), which is investigating the cause of the Jeju Air passenger plane disaster at Muan International Airport on the 11th, noted, "Analysis by the National Transportation Safety Board (NTSB) revealed that data recording on both devices ceased about 4 minutes before the aircraft collided with the localizer." ARAIC plans to identify the cause of the data loss during the investigation.
The accident occurred at 9:03 a.m. on the 29th of last month when the aircraft collided with a concrete mound where the localizer is installed at the end of Muan Airport's runway. At 8:57 a.m. on the day of the accident, the Muan Airport control tower warned the aircraft of a bird strike. The captain issued a mayday call due to the bird collision at 8:59 a.m., two minutes later, and communicated that they were returning.
According to ARAIC, the black box does not contain any data from the time the captain declared a mayday until the attempted landing. It remains unclear if the moment of the captain's mayday declaration was recorded on these devices. The aircraft's black box stops recording when power is cut, and it is known that the accident aircraft lacked a backup device that serves as an emergency battery.
The aircraft's radar-based tracking system (ADS-B) also confirmed that information transmission ceased at 8:58:50. ARAIC is continuing to analyze not only the control tower records from Muan Airport but also video footage of the moment of the accident and debris from the scene to reconstruct the incident.
Previously, the CVR was collected from the accident site in seemingly good condition, while the FDR was retrieved in a state that made analysis difficult due to a connector being lost between the power unit and the data storage unit. The CVR was analyzed at Gimpo Airport's own testing center, where data was extracted and converted to audio files. The transcript prepared on the 4th indicated that recording had ceased 4 minutes prior to the collision.
In response, ARAIC decided to conduct cross-validation in consultation with the NTSB and sent the FDR to the NTSB in Washington on the 6th, along with the CVR. The NTSB confirmed on the morning of that day to ARAIC that there was no recording from the last 4 minutes. Two ARAIC researchers attended the analysis process.
These researchers are scheduled to return home on the afternoon of the 13th with the FDR, CVR, and analysis materials. ARAIC stated, "We plan to provide information within the range that can be disclosed to the families of victims, including the completion time of the on-site investigation, if necessary," and said, "We will strive for a fair and transparent accident investigation."