Warning device event – Hamilton Island, Queensland, VH-TNX

On 15 February 2005, a de Havilland Canada DHC-8-102 (Dash 8) aircraft, registered VH-TNX, was being operated on a scheduled passenger service from Hamilton Island to Cairns, Qld. The aircraft was in instrument meteorological conditions with significant turbulence reported by the pilot in command, who was the pilot flying (PF).

During the climb from Hamilton Island, the PF engaged the autopilot while manoeuvring to intercept the outbound track. During a right turn at 2,624 ft above mean sea level, the Enhanced Ground Proximity Warning System (EGPWS) bank angle advisory activated. That advisory was in the form of an aural alert to the flight crew of 'BANK ANGLE, BANK ANGLE' when a roll angle of 35 degrees was exceeded, and the aircraft was greater than 156 feet above ground level.

Recorded flight data indicated that, while the aircraft was being manually flown, the angle of right bank was increasing as the autopilot was engaged. The angle of bank momentarily reached a maximum of 34.9 degrees, which activated the EGPWS. The PF briefly disengaged and re-engaged the autopilot a number of times during the manoeuvring. That included disengaging the autopilot during a subsequent left turn that was required to make good the outbound track, before re-engaging the autopilot for the remainder of the flight.

A post-flight engineering inspection found no fault with the aircraft's number one Attitude Heading Reference System (AHRS) or with the flight guidance computer system (FGC1). However, as a precautionary measure, these systems were replaced.