Narrative:

Possible over speed on approach. The first officer was pilot flying an ILS Z. Everything normal at 1000 ft 'stable' call out. I was looking outside as I was concerned about the preceding aircraft taking a long time to exit the runway. At some point between 1000 ft and 800 ft the first officer (first officer) called that she was disconnecting the autopilot. Again I was looking outside. At that point the engines surged forward because she had disconnected the auto throttles using the throttle disconnect switches. The international relief officer (international relief officer) reached up and deployed speed brake to avoid an over speed of the flaps between 600 and 700 ft. I believe the airspeed got over 170 knots though I cannot say for sure. I also grabbed the throttles; hit the disconnect switch and pulled them all the way to idle to get the airspeed under control. The aircraft remained on the visual glide path; red over white; throughout the entire incident. We touched down in the touchdown zone; at 135 knots and exited the runway without further incident. At no point did I feel safety was compromised. Just inexperience with the A330 throttle system. Initial upgrade/transition training should include detailed training on how to fly the aircraft with the auto throttles turned off. Especially for those pilots transitioning from boeing aircraft. A better understanding of the procedure to disconnect the autopilot would have prevented this uncomfortable event. The first officer explained the way she landed her previous [boeing] aircraft included disconnecting the auto throttles using the disconnect switches on the side of the throttles.

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Original NASA ASRS Text

Title: A330 First Officer reported an engine power surge on approach due to accidental disconnect of the autothrottles.

Narrative: Possible over speed on approach. The first officer was pilot flying an ILS Z. Everything normal at 1000 ft 'stable' call out. I was looking outside as I was concerned about the preceding aircraft taking a long time to exit the runway. At some point between 1000 ft and 800 ft the FO (First Officer) called that she was disconnecting the autopilot. Again I was looking outside. At that point the engines surged forward because she had disconnected the auto throttles using the throttle disconnect switches. The IRO (International Relief Officer) reached up and deployed speed brake to avoid an over speed of the flaps between 600 and 700 ft. I believe the airspeed got over 170 knots though I cannot say for sure. I also grabbed the throttles; hit the disconnect switch and pulled them all the way to idle to get the airspeed under control. The aircraft remained on the visual glide path; red over white; throughout the entire incident. We touched down in the touchdown zone; at 135 knots and exited the runway without further incident. At no point did I feel safety was compromised. Just inexperience with the A330 throttle system. Initial upgrade/transition training should include detailed training on how to fly the aircraft with the auto throttles turned off. Especially for those pilots transitioning from Boeing aircraft. A better understanding of the procedure to disconnect the autopilot would have prevented this uncomfortable event. The FO explained the way she landed her previous [Boeing] aircraft included disconnecting the auto throttles using the disconnect switches on the side of the throttles.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.