Aviation safety investigations & reports

Helicopter winching incident involving Eurocopter AS365, VH-WPX Near Swanbourne, Western Australia, on 29 September 2020

Investigation number:
AO-2020-053
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final

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What happened

On 29 September 2020, the crew of a Eurocopter AS365 ‘Dauphin’ helicopter, registered VH‑WPX and operated by the Western Australia Police Air Wing, were conducting water winching training exercises near Swanbourne, Western Australia. While conducting winching to a small vessel, a rescue crewman attached to the aircraft winch cable was pulled overboard and dragged through the water. The rescue crewman was recovered a short time later without injury and the helicopter was undamaged.

What the ATSB found

The ATSB found that the winching recovery sequence was interrupted when the rescue crewman lost footing on the deck of the vessel. The interruption, although communicated by the winch operator, was not recognised by the pilot, who expected the usual sequence to continue as had previously occurred on numerous occasions. As a result, the pilot instinctively increased the distance between the helicopter and vessel, and the rescue crewman was dragged overboard by the winch cable.

Further investigation found that crewman overboard drills were not regularly briefed or practiced, contributing to a breakdown in communication. This reduced the crew’s preparedness to respond effectively to such an event.

Finally, and though not a factor contributing directly to this event, the ATSB found that changes to sea state limitations contained within the Western Australia Police Air Wing Rotary Wing Operations Manual, were approved without the required review by the operator’s Safety Action Group. The absence of that review reduced the opportunity to identify any increased risk associated with the change. 

What has been done as a result

Following an internal safety review, the Western Australia Police Air Wing amended training and pre-flight briefings to include a crewman overboard scenario, and implemented crewman overboard drills during winch simulation training.

Furthermore, the Police Air Wing has introduced an alternative approach to open water vessel winching, that eliminates the risk while still maintaining the same level of rescue capability to the community.

With respect to easing of sea state limitations, the Police Air Wing has reinforced the importance of following change management principles and formal reviews to mitigate future foreseeable risks.

Safety message

Effective communication between pilots and crewmen is critical when undertaking helicopter winching as the pilot is required to safely manoeuvre the aircraft while unable to visually monitor the progress of the activity.

This incident demonstrates that even during highly trained and well-rehearsed operations, human performance limitations such as expectancy and reduced attention associated with a familiar task, together with deviations from standard phraseology, can have undesired outcomes.

Download Final report
[Download  PDF: 1.03MB]
 
 
 

The occurrence

Context

Safety analysis

Findings

Safety actions

Glossary

Sources and submissions

About the ATSB

General details
Date: 29 September 2020   Investigation status: Completed  
Time: 1215 WST   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): near Perth   Investigation phase: Final report: Dissemination  
State: Western Australia   Occurrence type: Miscellaneous - Other  
Release date: 22 September 2021   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Eurocopter  
Aircraft model AS.365N3  
Aircraft registration VH-WPX  
Serial number 6936  
Operator State of Western Australia - represented by Commissioner of Police  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Nil  
Departure point Rous Head, Western Australia  
Destination Offshore training area  
Last update 22 September 2021