A new ATSB investigation report has found an Airbus A320 turned onto final approach at Sydney Airport in a high-energy state, resulting in a flap and landing gear overspeed during a non-standard go-around.
While approaching runway 34L, the crew observed that the aircraft was high and selected ‘open descent mode’ on the flight control unit (FCU) in order to increase the aircraft’s rate of descent manually.
During the approach, the flight crew selected the missed approach altitude of 3,000 ft in the altitude window of the FCU and inadvertently pulled the altitude selector, which changed the aircraft’s vertical flight mode from open descent to ‘open climb’. In response to the mode change, the auto-thrust system, which was active at the time, increased thrust to climb the aircraft.
Unaware of the thrust increase, the first officer as the pilot flying and the captain as the pilot monitoring, continued configuring the aircraft for landing. The undetected increase in thrust destabilised the approach and led to a flap overspeed.
Observing that the approach was not stable, the captain commanded a go-around. However, a subsequent non-standard go-around procedure, including a lower than required pitch attitude, resulted in the aircraft accelerating faster than expected, which saw flap and landing gear speed limitations exceeded.
A go-around should immediately be carried out if the approach becomes unstable or the landing runway cannot be identified from the minimum descent altitude or missed approach point.
The captain took control of the aircraft, climbed to the missed approach altitude, and assumed the pilot flying role for the subsequent approach and landing.
The ATSB’s safety messages from this investigation include that unexpected events during the approach and landing can substantially increase what is already often a period of high crew workload. Adherence to standard operating procedures and correctly monitoring the aircraft and approach parameters best provides assurance that an approach can be safely completed.
The ATSB recommends a go-around should be immediately carried out if the approach becomes unstable or the landing runway cannot be identified from the minimum descent altitude or missed approach point.
Read the report: AO-2018-034: Flap overspeed during a go-around involving Airbus A320, VH-VQL, near Sydney Airport, NSW, on 9 May 2018.
Handling of approach to land is one of the ATSB’s SafetyWatch priorities.
Last update 06 June 2019