Aviation safety investigations & reports

Descent below minimum safe altitude involving Saab 340, VH-OLM, 9 km south Williamtown Airport, New South Wales, on 28 March 2019

Investigation number:
Status: Discontinued
Phase: Final report: Dissemination Read more information on this investigation phase

Discontinuation notice

Discontinuation notice

Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the 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. The statement is published as a report in accordance with section 25 of the TSI Act, capturing information from the investigation up to the time of discontinuance.

Overview of the investigation

On 8 May 2019, the ATSB commenced an investigation into the descent below minimum safe altitude involving a Regional Express Saab 340B aircraft, registered VH-OLM which occurred 15 km south-west of Williamtown Aerodrome (Newcastle Airport), New South Wales, on the evening[1] of 28 March 2019, at about 1942 Eastern Daylight-saving Time.[2]

As part of the investigation, the ATSB interviewed the aircraft flight crew and Williamtown Aerodrome air traffic controllers. The operator’s Route Manual was examined for information relating to the conduct of visual approaches and specific information about the operation of flights into Williamtown. The ATSB also reviewed Airservices Australia’s requirements of the conduct of visual approaches[3] and the required segment minimum safe altitude at Williamtown Aerodrome.[4]

Air traffic control (ATC) cleared the flight crew to conduct a visual approach via a right base circuit leg to runway 12, and told the flight crew to report once they were ‘on base’. The aircraft had descended to 900 ft when the flight crew contacted ATC to report that they were on base. The controller then looked for the aircraft again and observed that the aircraft was further away than the expected position (about 4.7 NM south of the airport) and according to the radar display, below the segment minimum safe altitude. The controller then issued a safety alert and instructed the flight crew to climb. The flight crew complied with the instruction to climb. The aircraft landed without further incident.

The ATSB found the flight crew had misjudged the aircraft’s position relative to the aerodrome while conducting a night visual approach.

ATSB comment

Based on a review of the available evidence, the ATSB considered it was unlikely that further investigation would identify any systemic safety issues. Consequently, the ATSB has discontinued this investigation.

The evidence collected during this investigation remains available to be used in future investigations or safety studies. The ATSB will monitor for any similar occurrence that may indicate a need to undertake a further safety investigation.


  1. The approach started five minutes before the end of nautical twilight.
  2. Eastern Daylight-saving Time (EDT) was Coordinated Universal Time (UTC) + 11 hours.
  3. Aeronautical Information Publication, 28 February 2019, Airservices Australia.
  4. DME or GNSS Arrival Procedures Williamtown, NSW (YWLM), 28 February 2019, Airservices Australia.
General details
Date: 28 March 2019   Investigation status: Discontinued  
Time: 1945 EST   Investigation level: Short - click for an explanation of investigation levels  
Location   (show map): 9 km south-west Williamtown Airport   Investigation phase: Final report: Dissemination  
State: New South Wales   Occurrence type: Flight below minimum altitude  
Release date: 25 May 2020   Occurrence category: Incident  
Report status: Discontinued   Highest injury level: None  
Anticipated completion: 2nd Quarter 2020    

Aircraft details

Aircraft details
Aircraft manufacturer Saab Aircraft Co.  
Aircraft model 340B  
Aircraft registration VH-OLM  
Serial number 340B-205  
Operator Regional Express  
Type of operation Air Transport Low Capacity  
Sector Turboprop  
Damage to aircraft Nil  
Departure point Sydney, NSW  
Destination Williamtown, NSW  
Last update 13 August 2020