The ATSB is investigating an occurrence involving Sikorsky S-92A, registration VH-IPE, 110 km north of Learmonth Aerodrome, Western Australia, on 01 February 2025.
During approach to an offshore vessel at night, the crew inadvertently disconnected the radar altimeter hold which would have stabilised the aircraft at a circuit height of 660 ft. The aircraft then continued to descend below circuit height and the crew subsequently received an E/GPWS TERRAIN alert and conducted a climb.
In the course of the investigation, the ATSB has identified potential limitations in risk controls relevant to the occurrence that are considered likely to have likely contributed to the occurrence. Examination of these factors represent a significant increase in the scope of this investigation, and it has been upgraded from Short to Defined as a result (the ATSB's different levels of investigation are detailed here).
The ATSB has commenced the examination and analysis of the initial evidence collected. To date, the ATSB investigation has included:
- interviewing the flight crew
- analysis of recorded flight data
- operator's procedures
- crew workload
- flight crew experience
- cockpit resource management
- operational risk assessment
- instrument lighting
A final report will be released at the conclusion of the investigation. Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties, so that appropriate safety action can be taken.