Aviation safety investigations & reports

Puma SA 330J Helicopter VH-WOF, Mermaid Sound WA, 12 May 1991

Investigation number:
Status: Completed
Investigation completed


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The aircraft was tasked to carry out a marine pilot pick-up from a departing tanker. The flight was conducted by two pilots operating under night visual flight rules. Conditions were a moonless night with no defined horizon, no outside lighting other than from the ship, and a surface wind that was light and variable. The ship was steaming in a northerly direction at 12.5 kts. The flight proceeded normally until the aircraft was established on final approach to the helideck. As the aircraft descended through 500 ft the rate of descent had increased to about 1,000 ft/min. Although the pilot in command increased main rotor pitch, the aircraft's rate of descent continued to increase until just prior to impact with the water. Both occupants were rescued approximately 1 h after they evacuated the helicopter. The report concludes that the standard approach technique used by the pilots, coupled with the prevailing weather conditions, caused the aircraft to enter a high rate of descent shortly after the aircraft started its normal final approach to the deck. The high rate of descent was probably the result of entry to the incipient stage of Vortex-ring state'. A lack of visual cues and inadequate management of cockpit resources prevented the crew from recognising the abnormal situation until the aircraft was well into the descent. Recovery action was commenced too late to prevent impact with the water.
Download Final Report
[Download  PDF: 2.7MB]
General details
Date: 12 May 1991   Investigation status: Completed  
Time: 2133 WST    
Location   (show map): near Karratha    
State: Western Australia   Occurrence type: Ditching  
Release date: 20 June 1993   Occurrence category: Accident  
Report status: Final   Highest injury level: Minor  

Aircraft details

Aircraft details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model SA330  
Aircraft registration VH-WOF  
Type of operation Charter  
Sector Helicopter  
Damage to aircraft Substantial  
Departure point Karratha, WA  
Destination 35 km NW Karatha, WA  
Last update 16 November 2015