Aviation safety investigations & reports

Flight below lowest safe altitude and ground proximity alert involving Leonardo Helicopters AW139, VH-PVO 44 km north-north-west of Latrobe Regional Airport, Victoria, on 4 March 2021

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


Download Final Report
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What happened

On the morning of 4 March 2021, the crew of a Leonardo Helicopters AW139, registered VH-PVO and operated by the Victoria Police Air Wing, were re-assigned from an aerial search near Coldstream to a search and rescue task in Orbost, Victoria. Due to the cloud conditions, the pilot upgraded the flight from visual to instrument flight rules. While en route to Bairnsdale at their cruising altitude of 5,000 ft, the helicopter entered cloud and shortly after the enhanced ground proximity warning system activated with the alert ‘caution terrain’. The pilot initiated a climbing left turn to avoid Mount Baw Baw, which had a maximum elevation of 5,138 ft.

What the ATSB found

The ATSB found that, while en route to Bairnsdale below the lowest safe altitude, the helicopter entered cloud in the vicinity of Mount Baw Baw, which resulted in activation of a ground proximity alert. The pilot identified the location of the terrain threat and conducted a climbing turn away.

The helicopter was below the lowest safe altitude as the pilot had incorrectly assessed the in-flight conditions as visual meteorological conditions after the helicopter reached 5,000 ft in the vicinity of Coldstream (based on their estimate of height above the cloud tops). As a result, the pilot elected to remain at 5,000 ft instead of recalculating the lowest safe altitude as the flight progressed.

The ATSB also found that the operator did not have a procedure for pilots when upgrading from visual to instrument flight rules in-flight. This would reduce the likelihood of an error when replanning in-flight, which was reported to be an infrequent task and higher-than-normal workload task, particularly in single-pilot operations.

What has been done as a result

After the incident, Victoria Police Air Wing developed an instrument flight rules upgrade procedure for inclusion in their operations manual. This procedure includes the acceptable methods for calculating lowest safe altitude and was circulated to all their pilots.

Safety message

This investigation highlighted the importance of lowest safe altitude calculations and to recalculate the lowest safe altitude appropriate for the area of operations.

Operators should also review their operations manual to ensure they have procedures in place to adequately capture their operating procedures in order to minimise the likelihood of decision‑making errors.

Download Final Report
[Download  PDF: 1.61MB]

The occurrence


Safety analysis


Safety actions


Sources and submissions


The Australian Transport Safety Bureau (ATSB) is investigating a flight below lowest safe altitude involving Leonardo Helicopters AW139, VH-PVO, 44 km NNW of Latrobe Regional Airport, Victoria, on 4 March 2021. 

During cruise, the aircraft encountered instrument meteorological conditions while below the lowest safe altitude and the crew received a ground proximity warning system alert. The crew immediately conducted a climbing turn to avoid the terrain.

As part of the investigation, the ATSB will interview the crew, review flight data, weather information, and gather additional information as required.

A report will be released at the end of the investigation. Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify those affected and seek safety action to address the issue.

General details
Date: 04 March 2021   Investigation status: Completed  
Time: 1140 EDT   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): 44 km north-north-west of Latrobe Valley aerodrome, Victoria   Investigation phase: Final report: Dissemination  
State: Victoria   Occurrence type: Flight below minimum altitude  
Release date: 02 December 2021   Occurrence category: Serious Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Leonardo Helicopters  
Aircraft model AW 139  
Aircraft registration VH-PVO  
Serial number 31878  
Operator Starflight Victoria PTY LTD contracted to Victoria Police Air Wing  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Nil  
Departure point Essendon Airport, Victoria  
Destination Bairnsdale Airport, Victoria  
Last update 02 December 2021