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 6 April 2018, the ATSB commenced an investigation into a Terrain Awareness and Warning System (TAWS) warning and missed approach involving a Beechcraft B200, VH-FDW, near Gladstone Airport, Queensland, on 5 April 2018.
During the conduct of the area navigation (RNAV) approach for runway 10 the pilot received a ‘Terrain, Terrain, Pull up’ warning. As the aircraft was in instrument metrological conditions (IMC), the pilot responded in accordance with standard operating procedure. Only a single warning presented and the pilot climbed the aircraft to an appropriate safe altitude. At that point, the aircraft was no longer in IMC and the pilot conducted a visual approach, landing without further incident.
The ATSB obtained additional information from the operator that identified the TAWS warning received as a nuisance alert. The aircraft was not in danger of impact with terrain and was safely established on the RNAV runway 10 profile. The operator had known about nuisance alerts on this approach since it was amended in 2010, when the final track was aligned over high ground near Mt Larcom. Other operators also experienced nuisance alerts in the same location.
The operator had implemented use of the TAWS flap override function to prevent nuisance alerts specifically for the Gladstone RNAV runway 10 approach. Before implementing this procedure, the operator consulted with the TAWS manufacturer and conducted a flight validation. On this occurrence, the pilot forgot to select flap override.
At the time of publishing, Airservices Australia had completed a draft revised RNAV runway 10 approach for Gladstone that was runway aligned and not over the high terrain leading to the nuisance TAWS alerts. While still requiring a flight validation, this new approach should eliminate the nuisance TAWS alerts.
The ATSB reviewed the information relating to this occurrence as well as information relating to previous TAWS occurrences involving the RNAV runway 10 at Gladstone. Based on this review, the ATSB considered it was very unlikely that further investigation would identify any systemic safety issues. Consequently, the ATSB has discontinued this investigation, but will continue to monitor TAWS occurrences involving all operators.
|Date:||05 April 2018||Investigation status:||Discontinued|
|Time:||0900 EST||Investigation level:||Defined - click for an explanation of investigation levels|
|State:||Queensland||Occurrence type:||E/GPWS warning|
|Release date:||21 August 2018||Occurrence category:||Incident|
|Report status:||Discontinued||Highest injury level:||None|
|Aircraft manufacturer||Raytheon Aircraft Company|
|Aircraft model||B200 King Air|
|Operator||Royal Flying Doctor Service of Australia (Qld Section) Ltd|
|Type of operation||Medical Transport|
|Damage to aircraft||Nil|
|Departure point||Brisbane, Qld|