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 18 May 2015, the ATSB commenced an investigation into a number of loss of separation occurrences and radar vectors issued to flight crew when an aircraft was below the minimum vector altitude on 18 May 2015, near Adelaide Airport, South Australia involving:
- a SAAB Aircraft Co 340B (S340), registered VH‑OLL (OLL), conducting a low capacity regular public transport flight from Mount Gambier, South Australia
- an Airbus A320-232 (A320), registered VH‑VNH (VNH), conducting a high capacity regular public transport flight from Melbourne, Victoria
- a Boeing 737‑8FE (B737), registered VH‑YVC (YVC), conducting a high capacity regular public transport flight from Melbourne
- a Boeing 737 (B737) conducting a high capacity regular public transport flight from Sydney, New South Wales.
The aircraft were under the jurisdiction of an Airservices Australia (Airservices) Check and Standardisation Supervisor (workplace assessor), conducting a final assessment on a trainee Approach East controller (trainee). During the approach sequence there were two loss of separation occurrences, then OLL was below the minimum vector altitude while on a vector on one occasion, and OLL was not confirmed above the minimum vector altitude while being vectored on another.
An Airservices investigation into the occurrences found that the Adelaide Tower controller did not have sufficient understanding of the minimum vector altitude, that the intervention by the workplace assessor was not effective and that the controllers involved in a transfer of separation responsibility did not have a shared understanding, as there was no standard phraseology. The investigation report identified the following safety issues:
- Compromised separation training for controllers at Adelaide Tower did not incorporate scenarios where aircraft were below the minimum vector altitued at night.
- The updated Intervention Techniques and Prompting initial qualification training was not provided to existing on-the-job training instructors or workplace assessors. Additionally, the relevent refresher training module had not been updated.
- There was no defined explicit requirements, including the required phraseology, for coordinating the transfer of separation responsibility between controllers.
Airservices subsequently advised that each of the safety issues had been addressed and all related safety actions had been completed.
The ATSB reviewed the Airservices report, safety issues and safety actions. 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.
|Date:||18 May 2015||Investigation status:||Discontinued|
|Time:||18:10 CST||Investigation level:||Complex - click for an explanation of investigation levels|
|Location:||near Adelaide Airport|
|State:||South Australia||Occurrence type:||Flight below minimum altitude|
|Release date:||31 January 2019||Occurrence category:||Incident|
|Report status:||Discontinued||Highest injury level:||None|
|Aircraft manufacturer||Saab Aircraft Co.|
|Type of operation||Air Transport Low Capacity|
|Damage to aircraft||Nil|
|Departure point||Mount Gambier, SA|