AS365 Crewman Dragged from Boat During SAR Training (Western Australia Police Air Wing Airbus AS365N3 VH‑WPX)
On 29 September 2020 Western Australia Police Air Wing Airbus AS365N3 VH‑WPX was conducting SAR training exercises near Swanbourne, Western Australia. While conducting an exercise with a small vessel, a rescue crewman attached to the hoist cable was pulled overboard and dragged through the water. The crewman was recovered uninjured.
WA Police Air Wing AS365N3 VH-WPX SAR Hoisting Incident: A series of still images captured from on-board video highlighting the commencement of separation and rescue crewman going overboard (Credit: via ATSB)
The Australian Transport Safety Bureau (ATSB) issued their safety investigation report on 22 September 2021.
The Day’s Training & Incident Flight
The crew commenced duty at 07:00 Local Time at their Jandakot base. They departed at 09:33 for a staging area at Rous Head, Fremantle, landing at about 09:50.
The crew for the exercises comprised of the pilot, four tactical flight officers (TFOs) and one TFO instructor. It involved the TFOs rotating through the roles of winch operator, rescue crewman and diver.
They conducted the first training exercise of the day at a nearby beach. The following exercises involved training with the 40 ft volunteer rescue vessel, Stacy Hall c 1-2 km offshore Swanbourne.
Stacey Hall (Credit: WAP via ATSB)
The aim was to conduct an initial vessel winching Operator Proficiency Check for one TFO and recency flights for two other crewmembers.
At the time of this incident the three key crew members were:
- The pilot: joined the Australian Army as a Blackhawk pilot in 2008 and then the WA Police in Sept 2019. They had 3,566 flying hours of experience, 320 on type.
- The hoist operator: who had served in the WA Police Air Wing since 2010, and had 1,596 hours of experience, including 110 cycles of water winching.
- The rescue crewman: who been with the Air Wing as a helicopter crewman since mid 2018 and had 864 hours, including 74 cycles as a rescue crewman.
The weather was overcast with clear visibility. The temperature was about 19°C with wind from the north‑west at 21 km/h (11 kt) gusting to 30 km/h (16 kt). Sea state was forecast to increase to 1.5 to 2 m during the morning.
After the first training it was decided only to conduct further operational recency training for the already qualified TFOs due to the sea state.
At 11:31, they departed from Rous Head for the third training sortie.
During a dummy run to the vessel the winch operator observed that the Stacy Hall was bouncing in the waves, so the crew requested…course and speed changes.
…as the rescue crewman was winched clear of the deck, they swung towards the canopy on the forward end of the deck and required the use of their arms to fend off…with the winch operator commenting to the crew that the sequence ‘…was pretty hairy’.
Further hoist training with the vessel and a helocast (free drop) / wet hoisting recovery exercise were conducted without issue, before a further return to Rous Head. This suggests relatively low concern about the sea state.
At 12:10 the helicopter departed to rendezvous with the Stacy Hall 1-2 km off Swanbourne for the fourth exercise.
WA Police Air Wing AS365N3 VH-WPX (Credit: WAP annotated by ATSB)
After take-off, the crew completed fly‑away checks, pre-landing checks, pilot brief and winch checks. The pilot brief confirmed the crew would undertake two hoist cycles to the vessel, which would be travelling on a course of 300° at a speed of 12 kt.
The helicopter approached the Stacy Hall and the pilot established the helicopter at the ‘datum position’ [maintaining reference and pace with the vessel at c100 m].
The crew then conducted a dummy approach run, during which the pilot reported having a good visual hover reference of the vessel. At the completion of the dummy run, the pilot terminated the helicopter at the ‘on-station position’ [maintaining station at no closer than three rotor diameters, providing the pilot and hoist operator with the best view of the vessel].
Onboard winch video recordings showed that at about 1215, the helicopter had moved from the on‑station position to the ‘transfer position’ [maintaining hover reference at adequate vertical clearance to allow for changes in swell, where the rescue crewman can be lowered to the deck with minimal risk of injury or likelihood of cable being fouled] and the winch operator commenced lowering the rescue crewman to the deck of the vessel.
At 1216, the rescue crewman landed on the aft deck of the rescue vessel and completed simulated checks. Within 2 seconds of landing on the deck, the rescue crewman gave the thumbs-up signal to indicate they were positioned, had completed checks and were ready to be winched up.
The hoist operator acknowledged the signal and reported to the pilot ‘one thumb up’ and ‘taking up the slack’.
The winch operator then winched in slack in the cable and reported that he and the rescue crewman were ‘ready to winch’. The pilot gave clearance to winch and the winch operator commenced winching.
At the same, the vessel’s interaction with the swell resulted in its deck pitching higher as it travelled over a wave. As a result, the rescue crewman lost their footing and moved down and backwards onto their back as the vessel’s aft deck rose on the swell.
The winch operator reported ‘crewman has fallen’ and immediately payed out cable to prevent it from becoming taut.
As the winch operator reported the rescue crewman was ‘adjusting his feet’, the pilot moved the aircraft back and left, increasing separation between the aircraft and the vessel.
In response…the winch operator advised the pilot to move the helicopter ‘forward two’, then with increased urgency in his tone ‘forward two, forward two’.
Despite those instructions from the winch operator, the separation between the helicopter and vessel increased. As a result, the winch cable became taut and the rescue crewman was dragged aft along the deck, into the transom and overboard into the water.
The following then occurred in quick succession, with a significant miscommunication/misunderstanding:
- The winch operator instructed the pilot ‘back, hold, hold, hold, hold’ with increasing urgency.
- The pilot responded, ‘I am holding’.
- The aircraft ceased moving away from the vessel and started moving forward as the pilot attempted to maintain position in vicinity of the vessel’s aft deck. The forward movement of the helicopter caused the rescue crewman to be dragged forward through the water towards the vessel.
- The winch operator commenced winching in, and the onboard video showed the rescue crewman emerge from the water.
- The pilot asked, ‘where is he?’, with the winch operator responding, ‘he’s just here underneath me’.
About 6 seconds elapsed between the crewman falling from the vessel, and emerging clear of the water. They were the hoisted back into the helicopter uninjured. The crew…
…decided to conduct another dummy run and briefly discussed their observations regarding the incident. The review of the incident did not include discussion of the helicopter movement. However, the TFO instructor provided feedback that in the event of a crewmember falling from the vessel, the correct response was for the winch operator to call ‘crewman overboard’ and ‘hold’.
About 1218 the crew conducted another dummy run, then decided to continue with the original planned training exercises.
This included a further helocast drop, again suggesting relatively low concern about the sea state.
Having completed the training…the aircraft returned to Jandakot, landing at 1243.
ATSB Safety Investigation
The WA Police Air Wing Rotary Wing Operations Manual stated that live vessel transfers be limited to sea state of 1.4 m. However, just one week before the incident, Operations Manual Bulletin No 7-2020 was issued. It stated that vessel training sea state conditions were “very restrictive for training with fully qualified crews”. As a result, the head of flight operations (HoFO) approved a change to sea state limitations for training of fully qualified crew to a 2.5 m sea state.
While the HoFO and their delegates were authorised to make such changes, formal review by the operator’s Safety Action Group was a prerequisite.
On this occasion, no such review by the Safety Action Group was undertaken.
The forecast sea state was within the Operations Manual Bulletin limit but higher that the Operations Manual.
The ATSB reviewed footage from the hoist camera:
There were no indications of any issues with how the pilot, or the other crew conducted the approach to the vessel, during the conning of the helicopter to the vessel…during the winch of the rescue crewman onto the vessel…and steps up to and including the winch operator calling ‘winching in’.
The next step is in the Operations Manual procedure is for the hoist operator to call ‘clear of the deck’. This indicate the person being hoisted ‘…is in a position where if they were to drift rearward relative to the vessel they would clear all rails and obstacles’. They then call ‘move back and right/left’ to the pilot. However in this case, immediately after making the ‘winching in’ call the hoist operator…
…saw that the rescue crewman had fallen on the deck and called ‘crewman has fallen’.
The hoist operator did not call ‘clear of the deck’ or request that the helicopter move away.
The pilot advised the ATSB that they commenced moving the helicopter away from the vessel in response to hearing the ‘winching in’ call from the winch operator. The pilot acknowledged that this was not consistent with the procedure…
The pilot believed that they instinctively separated from the vessel because that was the expected sequence of events, based on the procedure and their previous experiences in many similar exercises.
The pilot identified that training vessel winch exercises were normally conducted quickly, and they were therefore expecting to commence separating from the vessel immediately after hearing ‘winching in’.
On this occasion, the winch operator did not announce ‘crewman overboard’ [as required by the Operations Manual], instead they said ‘back’ and ‘hold, hold’ repeatedly with increasing urgency.
ATSB Human Factors Analysis
Studies show there will be an inevitable reduction in intentional effort and vigilance as procedural tasks become routine and habitual.
As described by Dismukes (2008): for experienced pilots, execution presumably becomes largely automatic and does not require deliberate search of memory to know what to do next. Pilots do not need to form an episodic intention to perform each task and each action step—rather the intention is implicit in the action schema for the task, stored as procedural memory.
Because of this, when routines are interrupted or changed there is an increased likelihood of errors. Reason (1990) described such phenomena as strong habit intrusions, noting that slips of action are most likely to be committed during the performance of highly automatised tasks, in familiar surroundings while experiencing some form of preoccupation or distraction. Dismukes (2008) summarises that “cues that normally trigger the habitual action are so strongly associated that the habitual action is often retrieved and executed automatically instead of the intended action if the individual does not consciously supervise the process”.
ATSB note that for the pilot the vessel hoisting procedure was frequently practiced, with over a dozen hoist cycles already conducted that day.
As a result, the pilot probably allocated a lower level of conscious attention to each and every aspect of the vessel winching procedure, including when to commence separating from the vessel.
Expectancy also has a powerful influence on attention and perception, and people are much less likely to notice information they are not expecting – particularly in the context of challenging work.
Consequently, the pilot was less likely to identify that the winch sequence had been interrupted and they needed to maintain position with the vessel.
The helicopter’s movement back and left, resulted in the rescue crewman being dragged overboard
In response to the initial helicopter movement the winch operator said ‘forward two, forward two’ attempting to con the aircraft back towards the moving vessel. After the rescue crewman fell into the water, the winch operator did not use accepted phraseology in accordance with the operations manual. Instead, they focussed on bringing the helicopter to the hover to prevent the crewman being dragged through the water by telling the pilot to ‘hold’ repeatedly with increasing urgency.
The pilot was unable to directly see the rescue crewman and “did not understand the developing situation or the position of the rescue crewman”.
As a result, the pilot took the meaning of ‘hold’ to mean maintain a constant position with respect to the moving vessel. The rescue crewman was subsequently dragged through the water, following the moving vessel.
Meanwhile, the hoist operator’s attention remained focussed on the crewman in the water. As a consequence their level of communication reduced.
This in turn required the pilot to ask ‘where is he’ in an attempt to increase their own situation awareness and mental picture of the developing situation.
Strangely the hoist operator told investigators that ‘crewman overboard’ was, in their opinion, “a drill and phraseology that, while taught, was not expected to be used”. They did however highlight that in contrast, other emergencies…
…were regularly drilled in recency and proficiency checks, including cable fouling, runaway cable, and communications failure and included in briefings.
ATSB comment that while the crew did do a debrief in-flight immediately after…
…the discussion focussed on the actions and phraseology of the winch operator rather than the pilot’s movement of the helicopter… Discussion of that element would have provided an opportunity to confirm that the required level of communication/coordination…was in place before the winching activity re-commenced.
ATSB Conclusions: Contributing factors
- After signalling they were ready to be winched from the aft deck of the vessel, the rescue crewman slipped and lost footing. This interrupted the usual sequential flow of water winching recovery from a vessel.
- With the rescue crewman still on the deck, the pilot reacted to a verbal communication from the winch operator and moved the aircraft away from the vessel, dragging the rescue crewman overboard.
- Having provided the ‘clear to winch’ call and received the ‘winching in’ response, the pilot had a high level of expectancy that they would shortly be given clearance to separate from the vessel. This expectancy probably led to the pilot instinctively applying the well‑rehearsed actions to separate and not identifying that the winch sequence had been interrupted.
ATSB Conclusions:
Other factors that increased risk
- After the rescue crewman fell into the water, the winch operator did not use the standard phraseology of ‘crewman overboard’. Because of this, the pilot did not have an understanding of the position of the rescue crewman.
- Crewman overboard drills were not regularly conducted or briefed prior to the conduct of vessel winching training. This reduced the crew’s preparedness to respond appropriately to such an incident.
- The operator increased the tolerances of sea state tables for training without conducting a formal safety review in accordance with their change management procedures. This reduced the opportunity to identify any increased risk associated with the change.
WAPAW Safety Actions
In response to their internal safety investigation, the WA Police Air Wing advised the ATSB that:
- Emphasised the importance of applying change management principles to mitigate any foreseeable risks.
- The WA Police Psychology Department is working with Air Wing Safety and Quality to develop and introduce mindfulness guidance and training within the non‑technical skills training syllabus.
- Crewman Overboard phraseology and response actions have been introduced into:
- operator proficiency check annual and biannual recency exams.
- winch operator training emergency response.
- winch simulator training.
- open water vessel winching briefs.
- The Police Air Wing has removed open water hoisting to small vessels from their operational capability.
Our Observations
Maintaining competence at over water SAR taskings is demanding when only practiced as a secondary capability. To their credit the WA Police were actively training for that secondary role and minor incidents are inevitable if realistic and demanding scenarios are conducted.
Its perhaps disappointing that rather than enhance their mitigation of risk after this incident that they have selected risk avoidance, namely removed the capability of hoisting from small vessels, instead.
The ATSB human factors analysis illustrates how expectancy bias can cause problems and how a comprehensive set of drill need to be practiced, even for rare emergencies.
Footnote
In 2016 we published this article that involved the same helicopter: Rotor Blade Tool Control FOD Incident
Safety Resources
The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn. You may also find these Aerossurance articles of interest:
- SAR Hoist Cable Snag and Facture, Followed By Release of an Unserviceable Aircraft
- HH-60L Hoist Cable Damage Highlights Need for Cable
- Guarding Against a Hoist Cable Cut
- Fatal Fall From B429 During Helicopter Hoist Training
- TCM’s Fall from SAR AW139 Doorway While Commencing Night Hoist Training
- SAR AW139 Dropped Object: Attachment of New Hook Weight
- Military SAR H225M Caracal Double Hoist Fatality Accident
- Fatal Taiwanese Night SAR Hoist Mission (NASC AS365N3 NA-106)
Recent Comments