“Engine failure! Cut cut!” Power loss during winching operations: the pre-eminent risk in your assessment?

helimer-javea“Clear door, ready to winch.” “Power assessment/hover scenario: Ditching/Committed/Flyaway/Safe Single Engine.” For most of us who fly multi-engine helicopter types, single engine performance and the choice of flight profiles deriving from this was introduced as a predominant consideration from the beginning of our flying training, and has remained there ever since. 

Our pre-flight calculations, our SOPs and even our flight checklists ensure that a possible power loss event remains at the forefront of our minds, and in most situations the guess-work and judgement is taken out of the equation anyway with strict parameters within which we are allowed to train and fly.

This creates a kind of availability bias. 

Availability bias is the fact that you are going to focus on what you know most about or have heard about before as a dominating risk, rather than evenly balance the risks. In this case, a power loss scenario. The problem is, the evidence clearly shows that in helicopter winching operations, power loss is not the dominating risk. In fact, it is far from it.

Incident and accident data from helicopter winching operations worldwide tell us that it continues to be as risky an activity as it ever was. It is made up of a broader and longer list of causal factors than are ever going to run through your head as you access the scene of the proposed winch operation and establish the hover. Some of these include:

  • Blade strike hovering near obstacle
  • Entanglement with gear (causing either attachment or unintended persons on winch)
  • Physiological degradation caused by chest strop
  • Casualty in strop losing consciousness
  • Roll out from hook
  • Shock load breaking wire
  • Attachment to rock-face/vessel
  • Loss of visual references
  • Accidentally hooked to weak harness point
  • Winching starts with person unattached or partially attached
  • Untethered hoist operator
  • Uncontrolled spin
  • Hi-line attached to person or object on the ground
  • Hi-line entanglement with person on winch
  • Hi-line weak-link insufficient for large high-powered rotorcraft
  • Tree blown down by hovering aircraft during winching
  • Aircraft enveloped by descending cloud-base during winch operation
  • Downwash causing fatal fall
  • Accidental cable cut

That’s too many eventualities to explicitly cover in briefing either pre-flight or in-flight. But which ones should we be prioritising and when? And are our SOPs and our decision-making processes flexible enough to allow us to tailor our profiles to the situations in which we find ourselves ?

I do not cite definitive statistics, but a quick scan of accidents and incidents in the past five years throws up five accidents involving fatal or serious injuries during helicopter hoisting. The most recent of these happened just this month in Japan, where a 77 year old lady fell 120 feet to her death after being incorrectly attached to winching equipment. It followed hot on the heels of another well-publicised incident in June of this year where a Phoenix Police crew grappled with an uncontrolled stretcher spin.

Accidents involving power loss during winching do happen, however they are rare. One took place in Iceland on 16 July 2007 when an AS365 Dauphin from the Icelandic Coast Guard ditched during winching following an engine failure. There were no fatalities and no injuries.

Safety management and reporting systems exist for us to readjust our approaches to how we operate based on the data that they produce. The weight of evidence suggests we should be shifting our focus to include other risk factors, inviting ourselves to think in new ways about how we are going to get caught out, and asking ourselves where the greatest risks lie in each case. What processes, procedures, or models can we put in place to help us to do this? What about our approach should we be re-evaluating? 

Winchops

As a community, should the technical crew be taking a lead on this, or does it necessarily require a whole crew approach? When I led a training session case study on a winching incident last year, I deliberately split the groups into front-seat and rear crews to see how they would take a different approach to assessing the risks. Sure enough, their considerations were dominated by their respective areas of expertise: they had been trained to think that way! Furthermore, the view of what constitutes the top risks from the differing perspectives and experiences of cockpit and cabin does not always coincide. How do we balance these off? How should we draw out and combine these different thought processes as effectively possible?

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