What happened
On 25 January 2024, an Airbus A320, registration PK-LUV, was operating a scheduled passenger service from Kendari to Jakarta. The flight, carrying 153 passengers, had previously completed a leg from Jakarta to Kendari earlier that morning. During the transit in Kendari, the flight crew consumed meals in the cockpit.
While cruising at 36,000 feet, the crew members removed their headsets and increased the cockpit loudspeaker volume. The Pilot in Command (PIC) requested permission to rest, which was granted by the Second in Command (SIC). After the PIC woke up, he again requested to sleep, and the SIC continued to manage both pilot flying and pilot monitoring duties alone.
At approximately 01:43 UTC, while the aircraft was maneuvering to avoid bad weather, the SIC also fell asleep. This led to a significant period of radio silence. Jakarta Air Traffic Control (ATC) attempted to contact the aircraft multiple times, even requesting assistance from other pilots, but received no response for approximately 28 minutes. The PIC eventually woke up, realized the aircraft had drifted from its intended flight path, and re-established communication with ATC, reporting a temporary radio issue before continuing to Jakarta safely.
The investigation
The KNKT investigation focused on the crew's physiological state and the airline's fatigue management protocols. Investigators found that the Second in Command had reported inadequate rest prior to the start of the duty day. The investigation also examined the cockpit environment, noting that the crew had transitioned from using headsets to relying on cockpit speakers, which may have contributed to the lack of awareness regarding ATC communications. Furthermore, the inquiry reviewed the airline's internal procedures regarding cockpit checks and the implementation of the 'IM SAFE' self-assessment checklist.
Findings
- The crew chose to operate while experiencing fatigue and an altered circadian rhythm.
- There was a lack of specific guidance from the operator regarding how pilots should manage fatigue and utilize scheduled rest periods effectively.
- The absence of detailed, standardized cockpit check procedures meant there was no formal mechanism to detect when a crew member had become unresponsive.
- The practice of sleeping during flight appeared to be an unaddressed method used by the crew to compensate for insufficient sleep prior to duty.