Incident to the Airbus A330 registered ZS-SXJ operated by SA Express Airways on 27/10/2024 en route

Preliminary data based on the notification from the South African authorities:

While en route to WMKJ at flight level (FL) 410, the aircraft began to oscillate between pitch-up and pitchdown movements, slowly gaining momentum. The copilot, who was the pilot flying (PF), immediately noticed the speed trend vector increasing to approximately 40 knots into the overspeed (red barber pole) protection area. To prevent an overspeed event, the autopilot (AP) was immediately disconnected, and the aircraft was gently pitched down to approximately 1.5 to 2 degrees, which stopped the speed acceleration. The speed trend vector then indicated a trend toward the vertical indicator/vertical protection (Vls/Vprot) range, as the aircraft descended, showing a similar 40 to 50-knot change in the speed trend vector.The aircraft diverted to O R Tambo International Airport (FAOR).