What happened
On 15 May 2015, while performing an arrival procedure toward Melbourne, Victoria, a Skytraders Airbus A319 descended to approximately 2,200 ft. This altitude was below the 3,000 ft level assigned by Air Traffic Control. During the period when the aircraft was below the assigned altitude, the Terrain Avoidance and Warning System (TAWS) issued several alerts. Additionally, the aircraft's speed exceeded the permitted limit for the configured flaps, and the Minimum Safe Altitude Warning System (MSAW) triggered an alert for the ATC controller.
During a critical 26-second window—starting from when the pilot flying pressed the thrust lever disconnect button until the aircraft reached its minimum altitude—the aircraft dropped over 1,000 ft and gained roughly 100 kt in speed. The crew eventually terminated the arrival procedure, climbed to a new cleared altitude of 5,000 ft, and proceeded to land at Melbourne.
The investigation
The investigation focused on the sequence of events leading to the altitude and speed excursion. It was determined that the incident began with an inadvertent switch selection by the pilot flying. This initial error triggered a rapid chain of events characterized by high workload and a combination of secondary errors. The investigation also noted that the crew appeared to be responding to a pitch-up illusion, which contributed to the uncontrolled descent and acceleration.