The Dunker

Pave Low John and I got to talking about underwater egress training for helicopter crews.

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One of the dozens of training courses that rotary-wing aircrew have to endure during their career is underwater egress training, also known as the infamous “Dunker Training”. The initial course is usually a day of academics and pool training, with annual refresher training scheduled once a year, usually at the base swimming pool. The reason this training is so important is because a helicopter crew that crashes into the water will almost always survive the actual crash. It’s during the egress from the sinking helicopter itself that most crewmembers are killed. I used to fly with an older flight engineer named Pat Hogan who was the sole survivor of an Air Force HH-3 Jolly Green that drifted back into the ocean off Okinawa during night water operations. He doesn’t even remember how he got out, he just got lucky. So crashing in the water, especially at night, was a situation that crews needed to be trained and equipped to handle.

[youtube https://www.youtube.com/watch?v=3BAqkXaM5sc]

With regards to equipment, the Air Force provided LPUs and HEEDS bottles for any aircrew that planned to fly beyond autorotational distance from shore. If you flew from a base next to the ocean, though, you wore them on every mission. LPUs were collapsible water-wings that were inflated by CO2 cartridges when you pulled a lanyard. They were bright orange and would keep you afloat even while wearing all your flight gear. However, you had to wait until you actually egressed the helicopter before you activated your LPUs or you would most definitely go down with the sinking aircraft. The HEEDs bottle was nothing more than a miniature SCUBA bottle with a mouthpiece regulator that fit in a holster on your survival vest. If you hit the water, you placed the HEEDS bottle in your mouth and it would provide at least a minute or two of air while you got untangled and exited your newly converted submarine. With a HEEDS bottle, you stood a much better chance of getting out of the helicopter. However, all of this required that you not panic and stay calm during a very stressful situation. Hence the one-day block of hands-on training in a semi-realistic environment.

This video, titled “Seconds to Live”, was the official training video that the USAF has been using as long as I can remember for aircrew underwater egress training. I suppose the Army and Navy have their own videos, but this is the only one I saw during my twenty years as an aviator. There are plenty of other videos on Youtube that show aircrew going through the training in a controlled pool environment. The “Dunker” itself is just a giant beer-can with seats in it that is lowered into the water while it rotates upside-down (helicopter are top-heavy, due to the main gear box and the engines, and roll over as they sink). It wasn’t until I attended initial training at NAS Jacksonville that I realized that most people dreaded the “Dunker”.

Being lucky enough to grow up next to a lake in NC, I had grown up swimming, jet-skiing, water-skiing, white-water rafting, you name it. Outside of being a water-polo player, I was about as comfortable in the water as one could be. However, some of the people in my class were not very comfortable in the water (we even had a bunch of helicopter mechanics from Ft Rucker in my class that flat-out admitted they joined the Army because they didn’t like swimming. Oops). Let’s just say it is a good thing they have divers on duty in the pool to pull people out if they start panicking or they would have killed half the class. You have to do five egresses and the last two have to be with the lights off to simulate a night ditching event. I didn’t have any problems but I saw some folks absolutely freak out when they dropped the big can into the water with the lights out. They make you keep doing it until you pass, so everyone passed, in the end.

The refresher training for us was much milder, you sit in a floating cage made of PVC pipe and just unlock your simulated harness and get out of that, all in your friendly local base pool. I had heard that the Navy made their guys use the underwater egress simulator a lot more, being overwater to a greater extent than Air Force rotor-heads. The Air Force probably should have done that as well, but remember, we are talking about the Air Force here. No reason to make it too painful, right?

All in all, I kind of enjoyed “Dunker Training”, it was the kind of stuff I imagined doing when I was growing up and dreaming of being a military pilot. However, I can definitely see why people that were not strong swimmers would dread it and I commend everyone that went through the course without tapping out, even as they hated every second of it.

XBrad- It’s a very real world problem. Here’s a scenario. An H-46 conducting Vertical Replenishment from the USNS Spica loses an engine while lifting a sling load and in hover out of ground effect. It’s able to immediately ditch the sling load, and get over the water, but settles into the water. The normally amphibious Sea Knight should have been able to move forward into translational lift, but the failure of the belly hatch meant the cabin filled with water. Watch just how fast the helo sinks.

[youtube https://www.youtube.com/watch?v=ixCEGxNgXKs]

In this case, all crewmen escaped (using both their LPUs and HEED).

4 thoughts on “The Dunker”

  1. Just reading this post brings back the palm sweat. I flew in the 70’s and 80’s, mainly in Sea Kings. I had a love-hate relationship with the dunker. It was cool and fun but it was also risky and the blindfolded portion of the training pushed me right to the ragged edge of panic a couple of times. Heeds didn’t come along until the mid to late 80’s and I HATED it (self waterboarded every firetrucking time) but recognized the potential lifesaving utility of the device. I was involved in one nighttime open ocean mishap. We all got out, we all credited our egress to dunker training, and none of us were 100 percent sure exactly how we got out.

  2. I’ve always remembered the chaos of the “dark” egress evolutions. During either my first or second time swimming for the exit, I got kicked hard, right in the face, from the spazz in front of me thrashing around while crawling his way over everyone else. Next time, I waited for the scrum to clear the cabin door (and it was a big opening, they made it even larger than the real thing) before I tried to get out.

    The one point they continually stressed was to grab a reference point and just go hand-over-hand for the exit. An underwater egress is so disorienting, you run the real risk of getting spatial disorientation if you let go with both hands to swim. Much easier to just grab a point and climb your way out, just like going up (or down) a ladder.

  3. Went through HUET once in my civilian seagoing career for the “possibility” of “maybe” being transported by helo in the oil fields. You aviation types have my respect. I’m pretty sure I would have been f**ked if I went down anywhere but a pool in simulator.

  4. I had never thought of it in these terms, but I watched a You Clip about military training and they had a former Spetznaz trooper on it. He said, “people think they will rise to the occasion, but it doesn’t work that way. Everyone falls to the floor. The floor is your training.”

    He’s right, and those people who can’t remember how they got out are an illustration of that fact.

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