Dynamic Rollout: An Unnecessary Risk
I operated as a helicopter rescue swimmer for almost a decade before hearing the phrase “ring rollout.” When you consider that the hoist-hook installed on U.S. Coast Guard aircraft at the time was the Mil-Spec hook pictured above and the most dangerous hook available, my ignorance of the concept is sobering.
Dynamic Rollout or Ring Rollout – regardless of the term used – is a situation that can occur when rescuers are hooked up to certain hoist hooks but not currently under a load. A properly hooked lifting eye or ring in any hook will stay put while gravity is at work, but when the rescuer is in the water or working on the ground or cliffside – when the hook hangs loose – the situation pictured above can happen. Sometimes the results are tragic.
In July of 2013, Las Vegas Metropolitan Police Department (LVMPD) Rescue Officer Dave VanBuskirk fell to his death during the rescue of a hiker from Mount Charleston. The NTSB determined that the cause was most likely dynamic rollout. Soon after the tragic incident, the LVMPD changed hooks and went to an auto-locking hook. Modern self-locking hooks are designed in such a way that accidental release from the hook is impossible.
If an auto-locking hook is not an option, rescuers must pay close attention to the geometry of the interface between the hardware and the hook. What kept me from finding out about dynamic rollout the hard way was probably the geometry of the hardware I was using. LSC lifting eyes are too small to clear the beak on the the Mil-Spec hook and other non-auto-locking hooks.
The interface of hardware to hook is always a consideration, but rings can be either too small or too large to roll out of a particular hook. The images below show two pieces of LSC hardware, one designed for direct interface with a helicopter hoist hook (the lifting V-ring) and the other (the talon hook) not designed for direct use with a hook.
Mountaineering and Rappelling Gear is Not Helicopter Hoisting Gear
Rescue program managers have to be aware that given the right set of circumstances, operators may try and use rescue hardware in a way it wasn’t intended and that can cause serious problems. In 2006, a mountain rescue team in South Africa was conducting helicopter hoist training with the South African Air Force.
Equipped with the gear they had, the mountain rescue team used a figure 8 descender as a common hookup point to the hook. Combined with the design of the hook on the SA330 Oryx Helicopter – better suited to cargo than to human cargo operations – the figure 8 rolled up while two crewmen were hooking up and it wasn’t until they were 13 meters above the ground that they noticed they were hanging from the gate of the hook, and not the hook itself.
They were safely recovered but the incident underscores the nature of the problem: that what you can do with your gear and what you should do are very different things. Watch the video below to get a better understanding of what ring rollout is and how it happens.
In my next post, we’re going to discuss the methods organizations use to mitigate this risk and others in hoisting operations, and how sometimes solving one problem can create others.
As a retired USCG Flight Mech, (H3, H52, and H65, pre-rescue swimmer at Clearwater & Miami) this issue was only addressed verbally only with a ‘keep downward tension on the hook’ at all times.
On a different note…do you have a good photograph of the old style hook with the grab ring? I’m working on some artwork to share with my fellow old timers. Thanks!
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