Diving incident at Eagles Nest Sink

[KevinNM]

I remember talking to somone who has been in Eagles Nest about the restrictions on the video and he said they were nearly not as bad as they looked in the video. Way past my skills to even want to do at 100 feet, much less close to 300.

Obviously they thought had a very damn good reason to ditch the CCR and swim out on OC. I hope we eventually figure out what it was.

 

[Dan]

Here's the gas density thread posted by Mr. Mitchell I mentioned earlier. Again, I'm NOT suggesting in any way this has anything to do with this incident. Simply pointing out what was learned.

Gas density guidelines

Here's the presentation.

Thanks for posting this very educational 55-minute video on CCR Physiology. The slide above pretty much tell me that the deeper you dive, the smaller margin of error you will have on exceeding the CO2 limit in your body to a point where you can simply pass out if you don't breathe harder to purge the CO2 out of your lung, especially for those CO2 retainer divers who have higher tolerance to CO2 level, where the brain slow to respond to your lung to breathe harder. The deeper you go, the less exertion you need to do. I understand now why those deep cave diver would use the dive scooter.

 

[oya]

View attachment 384004



The deeper you go, the less exertion you need to do. I understand now why those deep cave diver would use the dive scooter.

While this is generally true it's worth remembering, for the most part, bringing this up or relating the Shaw accident to this one in any way is a bit of a non sequitor.

At up to the Eagles Nest depths work of breathing can be mitigated by appropriate gas selection. With the experience these guys had it would be unlikely that they had something in their tanks that made their work of breathing high enough for this to be a factor.

 

[CuzzA]

While this is generally true it's worth remembering, for the most part, bringing this up or relating the Shaw accident to this one in any way is a bit of a non sequitor.

And I'll clarify a third time to make it perfectly clear, I only brought it up to use as an example something can be learned from an accident and I have no knowledge that it is in any way related to this case what so ever and it shouldn't be interpreted as such.

 

[Kevrumbo]

Ok here's the report originally posted by Charlie Roberson on CDF:

"Cave diving has a long history of accident analysis, which can be healthy and productive. Unfortunately, modern forms of communication and the twenty-four hour news cycle have trained us to expect up-to-the-minute reporting and rapid release of information. This is a reality of the modern world and without facts people are left to speculation and misinformation. The following statement of facts has been reviewed by those involved in the search and recovery efforts. That being said, there may be errors; however, these are the relevant facts as we know them.

STATEMENT OF FACTS

1. Chris Rittenmeyer and Patrick Peacock started a dive at Eagle's Nest around 2:00 p.m. on Saturday, October 15, 2016. They were on JJ-CCRs with 95cf sidemount bailouts. Each diver had a scooter and an AL80 safety. They also towed a backup scooter. They had placed all their deco safeties in the cave the day before.
2. Chris and Patrick were both fully trained as Full Cave, Trimix, CCR, and DPV divers. Both divers had years of ocean and cave diving experience.
3. When the divers failed to return to deco at the anticipated time, their surface support buddy checked every 30 minutes until they were several hours overdue. Their buddy called Cave Country Dive Shop around 6:00 p.m. and spoke to Jon Bernot, who immediately loaded his vehicle and started driving to Eagle's Nest. While enroute, Jon called around and activated a response team of qualified and available cave divers.
4. Search Team 1, of Jon Bernot and Charlie Roberson, got underway around 11:00 p.m. to search the upstream passage, which was the dive plan according to the buddy. Team 1 checked the habitat and spotted three O2 bottles at 20 ffw, four 50% at 70 ffw, and two 120 bottles on the top of the mound, all of which were untouched. Team 1 noticed that the 120 bottles were on the downstream side of the line but decided to go ahead and check the upstream since that was believed to be the dive plan. Team 1 scoured the entire upstream all the way to the far reaches of the Green Room, King's Challenge, and all the large passage and rooms. When Team I failed to find anything upstream, they proceeded to check the Lockwood tunnel to no avail. Team 1 surfaced around 3:30 a.m.
5. Search Team 2, of Ted McCoy and AJ Gonzales, got underway around 3:45 a.m. and headed downstream. They immediately found the two bodies on the exit side of the Pit in approximately 220-230 ffw. Team 2 fully documented the scene and took detailed notes for about 45 minutes before exiting.
6. Diver 1 was wearing his CCR but his bailouts were not in place. One empty 95 bailout was beside him and attached to his rig via a QC6 and the long hose was deployed. His loop was open and out of his mouth. The inhale side of the loop was crushed. He had 300 psi of O2 but no onboard diluent remaining. He did have a 13cf inflation bottle with gas remaining. He had no primary light head and his backup lights were not deployed. There was a single scooter near Diver 1 but it was unclipped and turned off.
7. Diver 2 was only wearing a drysuit, mask and fins and was positively buoyant. He had a backup light clipped off and dangling out of his pocket. No other bottles were nearby.
8. A full AL80 safety was located just on the exit side of the Pit restriction in 270 ffw but was not easily seen on the way out. The primary light head with e/o cord was also located on the exit side of the Pit restriction. Their other full AL80 safety was located beside another team’s full safety just downstream of the jump to the Lockwood tunnel.
9. Two 95 bailouts were located just on the far side of the Pit. Both were empty.
10. Recovery Team 1 brought both bodies to the top of the Ballroom and Recovery Team 2 brought both bodies to the surface on Sunday afternoon.
11. Diver 2's CCR, a 95 bailout, and two scooters were located on Monday morning just outside the restriction to Revelation Space in the Room of Dreams. The CCR loop was closed and appeared to be fully operational. The 95 bailout was full. Diver 2 had video lights for a GoPro plugged into his canister light.
12. The gear recovery team of Jon Bernot and James Draker removed all the gear from the cave and turned it over to law enforcement on Monday, October 17, 2016.

The nature of accident analysis is that it's critical of those involved. However, friends, family, and those involved in the recovery have many raw emotions regarding this loss. I ask that you keep this in mind as you proceed with a thorough and professional accident analysis.

Safe diving,
Charlie Roberson"

Revised Scenario below tying in the observations above as well as Dsix36's own harrowing experience:

Low visibility egress from Revelation, Diver2 trailing behind never sees Diver1 successfully negotiate the restriction ahead in normal CCR backmount & bailout tanks configuration. Diver2 goes open circuit on his bailout 95cf cylinder, decides to d'off his CCR and the other bailout 95cf tank in order to pass the restriction, has problems managing his extreme positive buoyancy, and in a zero visibility silt-out loses sight & contact with his dropped CCR & 95cf bailout tank. Diver1 finds him on the guideline exiting above out past the restriction, and they make the difficult & critical decision to abort a search down in the silt cloud for the dropped 95cf bailout cylinder. (Per Charlie Roberson's statement #11 above, the Recovery Team found the CCR in apparent operational order with the loop closed, and a full 95cf bailout cylinder at the Restriction to Revelation in the Room of Dreams).

Towed via the single back-up scooter, they make it back with difficulty because of Diver2's very positive buoyancy, through the Downstream Tunnel to the vertical shaft leading up to the Pit Restriction, with three 95cf cylinders clipped to Diver1, two of which are nearly exhausted supplying open circuit gas to Diver2. As last resort they look for the AL80 safety at 270ffw, "but was not easily seen on the way out" (per Charlie Roberson's statement #8) and don't find it. They ascend the narrow vertical shaft and exit at the far end of the Pit Restriction and drop the two empty 95cf bailout cylinders (found later by the Recovery Team, see statement #9 above).

They now have only one remaining 95cf cylinder which is likely at half tank pressure at best, which Diver2 breathes open circuit on the long hose, and Diver1 has already plugged into via QC6 (see statement #6) as offboard diluent supply -his own onboard diluent cylinder long ago emptied during the stressful extended return through the Downstream Tunnel. They have five minutes of gas left to negotiate the massive broken Boulder Field of the Pit Restriction, before scootering onward to find the AL80 safety tanks just before the Lockwood Tunnel jump . . .but ultimately get delayed or lost with deteriorating visibility & silt-out and tragically they perish.

Map:
EAGLE'S NEST - Association of Underwater Explorers

Dsix36's survivor's experience:
Diving incident at Eagles Nest Sink

 

[CuzzA]

So buoyancy control/rig placement is always stressed when doffing your rig at depth to prevent a scenario where you accidentally get separated from your rig and we've all done the drill when we were certified. Is there a different procedure for doffing gear when navigating a restriction? In other words, if you find you have to remove your rig to get past a restriction there will likely be a lot of silt, especially if another diver went ahead of you, and the possibility of losing your rig would be much higher, so do cave divers take this into consideration and perhaps use some sort of tether/line to prevent from losing their rig? Especially if there's a lot of flow that could send your rig even further away from you if you had to let go for whatever reason.

If not, why not? It would seem like that would be a good practice.

On a side note, for you rescue/recovery divers, I saw this product recently made by BigBlue dive lights in Clearwater, FL and apparently it allows you to see in zero visibility. I thought I would mention it if anyone hasn't seen it yet.

Welcome To Darkwater Vision

 

[DustyC]

Do they think he took his ccr off and continue to go deeper into the cave on OC? Or, was it removed at the turn around point?

I can't imagine that they'd do anything but call the dive if they ditched their primary system.

 

[wgw04024]

I can't imagine that they'd do anything but call the dive if they ditched their primary system.

That's what I was thinking as well.

 

[apitkin]

I remember talking to somone who has been in Eagles Nest about the restrictions on the video and he said they were nearly not as bad as they looked in the video. Way past my skills to even want to do at 100 feet, much less close to 300.

Obviously they thought had a very damn good reason to ditch the CCR and swim out on OC. I hope we eventually figure out what it was.

Well, speaking as someone who has been through that restriction a few times, I can tell you that on a good day it's easy. On a bad day it's very very difficult indeed.

The only reason to get out of his CCR was to get free of the restriction. It was clearly not a planned manoeuvre. Why he didn't get it back on we'll never know for sure.

Andy

 

[KMD]

For the record (if it matters to anyone) I do dive a JJ, I am fully trained with both trimix diving as well as cave diving and have dove at Eagles Nest.

The narrative given above leads to some questions as well as some assumptions that can be made on the conditions of the dive. Note that I base this based solely on the narrative on the report PfcAJ quoted from Charlie Robertson.

Diver 2 had just a dry-suit, mask and fins and was noted as positively buoyant. There is no mention if the diver 2 had some type of weight belt built in place to help offset the buoyancy. If indeed diver 2's plan was to ditch the CCR at the restriction, one would hope that some type of offset (I.e. weight belt) for the buoyancy of a dry-suit would be place. Either it was not in place, fell off during the exit (which would contribute to the difficulty of the exit). This is a bit of an assumption on my part.

Without a doubt, diver 2 was in serious difficulties during the exit. With no harness to attach bottles, extreme positive buoyancy of the dry-suit and also with no rig, there would have not been any capability to add gas to the dry-suit. On the way back depths in the tunnel get as high as 220-ish. Having to dip back down to 300' to navigate through the pit with no ability to add gas to the dry-suit must have been very uncomfortable. I think it fair to assume the workload of diver 2 was extremely high

Diver 1 also would have his hands full trying deal with the emergency trying to manage an out of gas diver who is so positively buoyant. Diver 1 may not even have enough negative buoyancy to stabilize the two of them. So I think it fair to say that the workload for diver 1 was extremely high.

It is roughly 600' from the room of dreams back to the pit. In that time two divers (one on CCR) ran through 3 95's of gas plus whatever dilluent was with diver 1. Their breathing and CO2 loading must have been through the roof.

All in all it presents a picture of two divers fighting like hell to get themselves and their buddies out and sadly coming up a bit short. This truly was a deck that was stacked against them.

The one oddity I had from the narrative was diver 1's inhalation loop being crushed while the loop was out of the divers mouth and open. I would have expected if there was a strong enough negative pressure to crush a loop, that it would have equalized by drawing in water through the exhalation once the loop left the divers mouth.

All in all a very sad situation.