Black box stopped recording 4 minutes before the collision… Expert: Shutdown possible

Korea Railroad Commission announces after cross-verification with the U.S. NTSB… It was cut off around the time of the ‘Mayday’ declaration.
The investigation period may be somewhat longer… “Analysis of various data, not just CVR and FDR”

It was revealed that the records of the last four minutes before the crash were not saved in both the flight data recorder (FDR) and the cockpit voice recorder (CVR), which are the black boxes of the Jeju Air accident plane.

Aviation operation experts analyzed that the recording may have been interrupted when both engines failed after the accident plane collided with a bird, putting the aircraft in a power shutdown state.

On the 11th, the Ministry of Land, Infrastructure and Transport’s Aviation and Railroad Accident Investigation Committee (HRC), which is investigating the cause of the Jeju Air passenger plane disaster at Muan International Airport, said on the 11th, “As a result of analyzing the FDR and CVR of the accident aircraft by the U.S. National Transportation Safety Board (NTSB), the aircraft collided with the localizer. “It was discovered that data storage had stopped on both devices for approximately four minutes prior to this.”

The Port Authority plans to determine the reason why data was not saved during the accident investigation.

The accident occurred at around 9:03 a.m. on the 29th of last month when it collided with a concrete berm on which a localizer was installed at the end of the Muan Airport runway.

At 8:57 a.m. on the day of the accident, the Muan Airport controller warned the accident plane of a collision with a bird (bird strike). Two minutes later, at 8:59, the captain called out a mayday (distress signal) due to a bird strike and announced a return trip.

According to the Port Authority’s explanation, there was no data left in the black box containing the situation from the time the captain declared a mayday until the altitude was increased and the landing was attempted. It has not been confirmed whether the moment of the captain’s mayday declaration was recorded on these devices.

Aircraft black boxes stop recording when power is not supplied, but it is known that the accident plane did not have an auxiliary device that acts as an emergency battery in such cases.

It was confirmed that the accident plane’s radio-based aircraft tracking system (ADS-B) also stopped transmitting information at 8:58:50. This point supports the assumption that a shutdown occurred.

Kim Gwang-il, a professor of aviation operations at Silla University, said, “It is an extremely rare occurrence, but it is presumed that the generator stopped when both engines failed to operate, and the CVR, FDR, and ADS-B were all cut off.” “It appears to be,” he said.

Jeong Yun-sik, a professor of aviation operations at Catholic Kwandong University, also interpreted, “The fact that data storage was stopped four minutes before the accident means that it is highly likely that it was an electrical fault.”

He predicted, “The accident investigation period may be longer as we uncover the exact cause of data storage interruption and cross-verify with other data.” In the past, in the case of domestic airline passenger plane accidents, it took as little as 11 months to as long as several years to announce the results of the investigation.

In relation to this, an official from the Port Railroad Commission said, “The investigation is conducted through analysis of various data, not just CVR and FDR data,” and “We will reveal whether the cause of the data storage interruption was loss of engine power or a connection cable device error, and determine the exact cause of the accident.” “I will do my best,” he said.

In order to reconstruct the moment of the accident, the Anti-corruption and Railroad Commission is continuing to analyze Muan Airport control records, videos containing the moment of the accident, as well as debris parts from the scene.

Previously, at the accident scene, the CVR was recovered in an apparently intact condition, and the FDR was collected in a condition that made analysis difficult due to the loss of the connector between the power source and the data storage unit.

CVR retrieved data from Gimpo Airport’s own test analysis center, converted it to an audio file, and created a recording on the 4th. As a result, it was found that storage had stopped 4 minutes before the collision.

Accordingly, the Korea Railroad Commission decided to conduct cross-verification in consultation with the NTSB, and sent the FDR to the NTSB in Washington on the 6th along with the CVR.

As a result of analyzing the two devices, the NTSB confirmed that there was no record of the last four minutes and notified the Port Authority this morning. Two investigators from the Anti-Imperial Committee were present during the analysis process.

These investigators are scheduled to return home on the afternoon of the 13th with FDR, CVR and analysis data.

The Port Authority said, “We plan to provide as much information as possible to the bereaved families, etc., if necessary, including when the on-site investigation is completed,” and added, “We will strive to conduct a fair and transparent accident investigation.”

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