What happened
During the arrival phase of the flight, the crew utilized the autopilot's vertical navigation path (VOT) and auto throttle to manage the descent and airspeed. While in a clean configuration, the aircraft was unable to reduce speed sufficiently to meet both the descent profile and the speed restrictions required by the Standard Terminal Arrival Route (STAR). Consequently, the aircraft maintained an airspeed approximately 30 kt above the permitted limits.
Upon receiving a speed reduction instruction from air traffic control, the crew modified the aircraft's configuration to comply. The crew perceived the controller's instruction as urgent, which increased their operational workload. As the aircraft decelerated to the required approach speed, the crew failed to arm the speedbrake and did not perform the necessary landing checks. By the time the aircraft passed 1,000 ft above the airfield elevation, the approach was no longer considered stabilised because the landing checklist remained incomplete and the speedbrake was not in the armed position.
The investigation
The investigation examined the crew's management of the descent and the impact of the air traffic control instruction on their performance. It was noted that the crew's focus shifted toward monitoring airspeed and extending flaps promptly. This focus likely led to attentional narrowing, where the crew concentrated on a limited set of information at the expense of other procedural steps. Additionally, the captain noted that monitoring performance may have been affected by a lack of recent flying experience.
Findings
- The crew did not take timely action to reduce the aircraft's speed when it exceeded the STAR restrictions.
- The crew failed to arm the speedbrake and complete the landing checklist due to a focus on achieving the ATC-requested airspeed reduction.
- The flight crew did not recognise that the approach criteria were not being met as the aircraft descended below 1,000 ft.