Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.

On 1 April 2011, the ATSB commenced an investigation into an operational event that occurred at about 1910 Eastern Daylight-saving Time on 29 March 2011 involving a Bombardier DHC-8-402 aircraft, registered VH-QOP. The initial report indicated that, during the descent into Canberra, at an altitude of about 9,000 ft, a turn was commenced in preparation for the approach. During the turn, the aircraft bank angle was reported as approaching 45º, before returning to normal.

The ATSB conducted an analysis of the aircraft's flight data recorder, and along with crew interviews, identified that the maximum bank angle in the turn was 40º. The crew did not receive a 'bank angle' warning from the aircraft's enhanced ground proximity warning system (EGPWS). The crew interviews also indicated that the pilot flying was very experienced.

The ATSB's primary focus is on enhancing safety with respect to fare-paying passengers and, in particular, those transport safety matters that may present a significant threat to public safety or are the subject of significant public concern. The ATSB therefore directs considerable attention to identifying systemic failures in the aviation, marine, and rail modes of public transport.

The ATSB considered there was limited potential to enhance transport safety by continuing this investigation, and has elected to discontinue it. However, the data already collected may be used by the ATSB for future statistical analysis and safety research purposes.