ATSB closes the book on Jetstar turbulence event

“Flight data analyses by the ATSB and the aircraft’s manufacturer, Airbus, have concluded this incident did not result from any flight control abnormality, or involve unexpected behaviours by the flight systems,” ATSB Chief Commissioner Angus Mitchell said.

“Put simply, the turbulence activated the flight protection systems, and these systems disconnected the autopilot for the flight crew to manually manage the event.

“The flight crew responded appropriately, and re-established the desired descent profile prior to joining the approach, before reconnecting the autopilot and landing without further incident.”

As noted by the ATSB, during the descent, westerly winds of 40–50 kt were recorded by the aircraft’s digital flight data recorder, and the flight crew reported moderate turbulence.

While turning before joining an approach for Sydney’s runway 34 left, the flight crew felt a larger turbulence encounter, pitching the nose up and the aircraft’s flight envelope protection activated, restricting the angle of attack, while disconnecting the autopilot.

The first officer re-engaged the autopilot, but turbulence once again activated the flight envelope protection, so the autopilot disengaged again.

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The captain then took control and manually lowered the nose, and the flight envelope protection deactivated.

According to Mitchell, the sequence of events, an explanation of the systems involved, and an analysis of flight data, were detailed in a Discontinuation Notice, but the ATSB felt no further investigation was needed.

“Pilots and operators of similar aircraft are encouraged to review this information for their own awareness,” he said.

“But, in line with our responsibility to use our resources for maximum safety benefit, we have determined no further investigation is required in this case.”

The Discontinuation Notice is available on the ATSB’s website.