"Reducing PSD fatalities by 20%" and "Searching the 3rd Dimension"

[BladesRobinson]

Why is resuscitation necessary? The back up should be able to get down to clear the primary be it under ice or anywhere else well within the parameters of a "safe" dive time. <---BLADES AGREES. RECUSCITATION WOULD BE THE LAST OPTION, DEPLOYING A SAFETY WOULD BE THE FIRST OPTION. THE POINT I WAS MAKING PREVIOUSLY IS RELEASING A Q.R.S.S. IS ALWAYS A LAST OPTION IN ANY SITUATION EXCEPT UNDER ICE. IN THOSE SITUATIONS WE ALL AGREE THAT WE WOULD NOT WANT THE DIVER TO SEPERATE FROM THE SEARCH LINE.


Another thing .......... is that it would seem to point out that we should not try to pull a diver out of a snag or entanglement. <---BLADES AGREES. NEVER PULL A DIVER WHO HAS GIVEN A DISTRESS SIGNAL. IN THE PREVIOUSLY REFERENCED NIOSH REPORT, DIVER #3 WAS NOT TRYING TO PULL THE VICTIM BY THE SEARCH LINE.

I've given an answer of how to solve the problem of a trapped diver without him having to d/c from his tether but nobody has been able to give me an example of why this answer doesn't work. SEE BELOW ... Blades

Very good discussion thus far. Thanks to all that have taken part.

........................................................................

Mark...

This is an EXCELLENT discussion. Thanks a million for keeping an open mind, using sound logic and asking good questions. You are keeping me on my toes and members of the forum are learning here too. You asked for an "example" so I will throw out three real world incidents, and then I will follow with a tough question...

I will start with Art Schumacher...

Art was the coordinator of his dive team (like you)
and he too had considerable diving experience;
his highest rating was "divemaster" and he held
the rank of Assistant Chief. Art was a public
safety diver who died at age 46 wearing a
nylon chest harness with a nylon rope attached
to his chest harness via a locking carabiner.

Art and his team members were dispatched to a
report of a vehicle in a rain swollen creek.
When they arrived, the vehicle had already come
to rest against a culvert pipe passing beneath
County Road 42 in Medina County, OH. It was cold
and early in the morning and they arrived on scene
around 4 AM. Art made a decision to enter the water.

He was "only going to check under the car and
along the side" one teammate stated.

Minutes after entering the water, Art was sucked
under the vehicle and into a culvert pipe that
was 5 feet in diameter. There were no line pull
signals since the search line had been pulled
taunt against the underside of the vehicle. A
few minutes after entering the water, team
members knew Art had a problem. The search
line was pinned under the vehicle so they could
not give slack allowing Art to exit the pipe
on the down current side. The vehicle was
removed via a wrecker and at 0520 hours, Art
Schumacher's body was pulled from the culvert
pipe. Art was still wearing his chest harness,
nylon rope and locking carabiner, and a dive
knife. Additionally, he had 2400 psi in his
SCUBA cylinder and his regulator functioned
normally; his mask was still in place. A senior
company officer, well trained, with considerable
experience died because he could not release
himself from his search line and exit on the
down stream side of the culvert pipe. He was
less than 25 feet and 5 seconds from the pipe exit.

Charles David Hartman (age 30) was an experienced
public safety diver (police officer) who entered
flowing water wearing SCUBA gear and a search line
attached via a carabiner. He too died when he
could not release from his search line. Teammates
and spectators on site watched him on
the surface for a period of time and didn't know there
was a problem until it was too late. Water currents
caused Officer Hartman's body to move in a life-like
motion and it was only after a short period of
time that personnel on shore realized the seriousness
of the situation.

Frank Hut (age 28) died in the relatively calm waters
of a South Carolina Sound. Frank had submerged,
made a dive, and returned to the surface for
another tank of air. Unfortunately his comm rope
had wrapped under a submerged cable. When wind
shifted the dive boat slightly, he was pulled underwater
with the submerged cable acting as a directional pulley
on his comm rope. Even though team mates responded
promptly, they were unable to save Frank's life. ​

Reflecting on these three incidents, I would ask the forum members, who believes that clipping onto the victim's search line and swimming towards the victim would have any benefit? Maybe in the last situation but by the time Frank's rescue diver arrived, Frank was already unconscious. I wonder how many additional minutes were lust becasue the rescue diver could not activate a quick release system. In the case historys above, is it not possible to believe that Q.R.S.S. would have made a difference?

I am not saying that deploying a safety diver is a bad thing. DEFINITELY NOT...

What many people believe (including myself) is there are times when a quick release snap shackle can make a difference between life and death. If the diver is using a carabiner, it can not be released under load and, as pointed out, death can result. A snap shackle can have the strength of a carabiner and the benefits of being released by the diver in an emergency. Why would we not want to use a safer device that allows the diver to have options? Why is a knife or cutting shears the only "last option" we presently give to the divers during their last moments of life? If we can trust a diver to cut himself free, can we not trust him to pull a quick release snap shackle?

As one of our Bother PSDs pointed out earlier, commercial divers have been using quick release snap shackles for years. They are used in the water rescue community too! So I would like to ask, why are Q.R.S.S. bad for public safety divers?

 

[BladesRobinson]

Friends, I was just reflecting on past tragedies and recalled the Yakima disaster that claimed the lived of four divers (two "recreational, two "psd"). Having four divers killed on a single incident made headlines but no one reported the two other PSDs that ALMOST perished. In all of my reading, I have never seen the "rest of the story" printed anywhere, except in a binder given to me by one of the investigators.

OVERVIEW:
Labor & Industries closes diver drowning probe
By STACI A. WEST
Herald staff writer

Poor training and planning doomed two Yakima County Sheriff's rescue divers who died along with two commercial divers in a Zillah irrigation canal in March.

That is the decision of the state Department of Labor and Industries, which just completed its investigation of the fatal diving accident. The agency decided it did not have jurisdiction over the attempted rescue because the rescue divers were volunteers. However, the regional administrator has sent a stern letter to the Yakima County Sheriff.

"They just flat blew it," said Reuel Paradis, L&I regional administrator for Central and Eastern Washington. "It was preventable had management had all the pieces in place. In this incident, we don't believe every possible (safety precaution) was taken."

Paradis told Sheriff Doug Blair in a letter Tuesday the sheriff's department will not be cited. If the divers had died while recovering a body for the sheriff's office, then L&I would have had jurisdiction, Paradis said. L&I has offered to work with area search and rescue teams to make sure the tragedy does not repeat itself.

It was the most severe occupational injury case ever in Eastern Washington.

On March 15, commercial divers M. John Eberle, 41, of Grandview and Marty Rhode, 34, of Sunnyside drowned after diving into a 2,300-foot-long irrigation canal that reached 104 feet under Cheyne Road near Zillah. They were searching for abandoned vehicles in the 13-foot-diameter underground siphon for Roza Irrigation District.

Two divers with Yakima County Search and Rescue, Charlie "J.R." Mestaz, 37, of Moxee, and Rusty Hauber, 34, Yakima, died while trying to rescue the commercial divers. When Mestaz and Hauber did not surface within 40 minutes, a third pair of divers went in.

Paradis also blamed supervisors who allegedly did not understand the hazards posed by the siphon's murky, nearly freezing water and confined space. The irrigation canal should have been considered a type of cave, which requires extra precautions for divers, Paradis said.

In his letter, Paradis said all four rescue divers were undertrained and underequipped. Emergency supervisors apparently did not properly calculate the amount of air or decompression time divers would need, the letter said.

"There is no evidence they had any of these things calculated in their dive plan," Paradis said Tuesday. "People were being driven by adrenaline and not by good planning."

L&I has fined the Roza Irrigation District $37,900 for 10 violations of worker safety involving the commercial divers' deaths. Those divers did not wear lifelines, were not experienced in cave diving and ran out of air. The district has appealed the penalties.

Sheriff Blair was out of town Tuesday and had not seen the letter from Paradis. Chief Criminal Deputy Stew Graham said he doesn't understand why the agency sent the letter if it doesn't have jurisdiction.

"We thank the agency for their concern," Graham said. "The sheriff had many of the same concerns and addressed them early on."

After the deaths, Blair announced the search and rescue team would no longer do rescues for overdue swimmers and instead would consider all drowning situations as a body recovery. He also plans to contract with a local professional diver to train the sheriff's divers, Graham said.

The Zillah accident should have been treated as a recovery of bodies, Paradis said. It had been two hours since anyone had seen bubbles from the commercial divers' tanks. By then, the commercial divers could not have been revived if they were pulled from the water.

Two days after the diving accident, Columbia Basin Dive Rescue members from the Tri-Cities recovered the divers' bodies. They spent nearly four hours planning who would go into the canal and how, said Neil Hines, dive rescue president.

Divers followed strict rules and checklists on what to do in confined-space dives. And each diver wore a full-body harness attached to a lifeline.

"There's so many things when you go into a confined space that you have to follow," Hines said. "You can only go with what your capabilities are. They didn't do anything by the book."

Paradis agreed in his letter. "Diving activities ... are arguably the most dangerous activities expected and undertaken by search and rescue team members," he wrote. "It is critical for the dive team members to have the highest levels of training and equipment."
MORE OF THE STORY:
Divers John Eberle and Marty Rhode were probably dead before rescue divers Charlie "J.R." Mestaz and Rusty Hauber entered the water. Regardless, they did their best to give the first two divers a chance and attempted a "rescue mission." Mestaz and Hauber carried a spare tank and regulator with them so they could pass it off to the victims, assuming they could have found an air pocket and been alive. Both rescue divers wore full face masks which would have been removed had the needed to use air in the spare cylinder they carried. They planned their dive for 30 minutes with a 5 minute stop at a depth of 15'. The safety divers were supposed to meet the primary divers at the 15' stop to assist as needed.

Investigators believe the rescue divers located the deceased victims and attempted to remove them. This is based on the fact that Hauber's maximum depth indicator read 100' - the deepest point in the canal siphon. Investigators also believe that shortly after attempting to bring the victims out of the siphon, Hauber and Mestaz realized they were running low on air, released the victims and started swimming for their lives to the exit point. As the rescue divers exhausted their air supply, Mestaz apparently removed his full face mask and began using the spare cylinder as he continued his attempted to exit.

THE REST OF THE (PREVIOUS) UNTOLD STORY ...

The safety divers on the surface waited for 30 minutes to pass. At 25 minutes they began to notice a glow from a dive light in the water and at 30 minutes the two safety divers started their decent to the 15' deco stop (that was fairly far back in the canal siphon - pipe). The two safety divers (Diver #1 & Diver #2) clipped onto the same line that the rescue divers had clipped to using carabiners. When the safety divers reached the 15" safety stop, the disaster became apparent. Mestaz was discovered first, mask off, unconscious. The diver #2 quickly swam back to the siphon entrance to alert the crew topside of the emergency and instructed them to start pulling in the line. When the diver #2 returned, diver #1 had become disoriented. Because diver #1 had focused attention to one of the victims and got turned around, when she got back to the primary line (running horizontaly through a near horizontal pipe) she could not determine which was was out. Diver #2 was able to provide proper orientation and both divers, LUCKLY, were able to exit safely. The safety divers grabbed Mestaz and brought him to the surface where recuscutation efforts began. Mestaz was in a coma for 3 days before he passed away. Hauber died the day of the incident.

SO WHAT'S THE POINT OF THIS STORY ? ? ?

When a safety diver is clipped to a search line and he gets to the midway point and has to resolve an issue (possibly a cramp, loose fin strap, whatever ...) when ge gets back to the search line (in limited vis) how does he know which way to swim in order to reach the victim? There is a 50/50 chance, just like Diver #1 in Yakama, that he is going to swim in the wrong dorection.

Let's say now he is going to rescue the entangled victim and has to cut the search line in order to free the primary diver. Isn't there a probability that the stand-by diver's carabiner is going to slide off the end of the cut search line? What happens if this is the case where the primary diver is panicked and pulls the full face mask off of the stand-by diver. How does the 90% diver find the other two divers?

I know there are a lot of "what ifs" here but because of a "real world" incident where a safety diver clipped onto a line and became disoriented, is this topic worth discussing too? Do we need to create a new "topic?"

Back to my friend in Alberta...

Blades

 

[bridgediver]

When a safety diver is clipped to a search line and he gets to the midway point and has to resolve an issue (possibly a cramp, loose fin strap, whatever ...) when ge gets back to the search line (in limited vis) how does he know which way to swim in order to reach the victim? There is a 50/50 chance, just like Diver #1 in Yakama, that he is going to swim in the wrong dorection.

Let's say now he is going to rescue the entangled victim and has to cut the search line in order to free the primary diver. Isn't there a probability that the stand-by diver's carabiner is going to slide off the end of the cut search line? What happens if this is the case where the primary diver is panicked and pulls the full face mask off of the stand-by diver. How does the 90% diver find the other two divers?

I know there are a lot of "what ifs" here but because of a "real world" incident where a safety diver clipped onto a line and became disoriented, is this topic worth discussing too? Do we need to create a new "topic?"

Back to my friend in Alberta...

Blades

Sorry its taken me so long to get back to this - very busy these days but to answer your question, the back-up diver also has his own tether and tender which is controlled in the normal manner (good tension, signals etc) so he is always able to figure out which way his tender is. If the 2 divers decide to cut the primary's tether they will use the back-up's line and are still in contact with the surface. Before cutting, the back-up will use the "contingency strap" I metioned before to clip onto the primary so he won't loose him - now both divers are tethered to the back-up's line. The surface knows exactly where both divers are at all times
As I said before, the likelyhood of the back-up's tether becoming entangled is extremely low as the back-up is going straight out and not sweeping as the primary likely was and most likely was the cause of the entanglement. The back-up will also find the entanglement with his hands as he progresses down the primary's line and so should be able to avoid it.


The above story that you've provided is way above and beyond what these methods would work for. I'm not sure any regular PSD methods would - too far, too deep, too much overhead. Experienced cave divers should be the only ones to attempt such an op IMO

 

[BladesRobinson]

Mark,

Thanks for the explanation. I was unaware that the safety diver would be clipped onto the primary diver's line AND an additional line running from shore.

Certainly in the case previously described, there are a lot of "what ifs" and hopefully good training would prevent that situation from ever happening again but I was curious to know how our brothers on the other side of the border would prevent that.

As you probably know, in the system commonly used here, the back-up diver would only be tethered to his search line and would not be double clipped (connected to the primary diver's search line).


Thanks again for the explanation.

Blades

 

[bridgediver]

Blades, I also wanted to examine the 3 examples you gave more closely in an attempt to learn from them through discussion. You've given these examples to support your opinion on the quick release shackles. If they were used these divers may have survived their ordeal; then again they may not have. We will never know.
I do think that there are other issues at work that had a greater bearing on the outcome than did the locking carabiner - but that's just my opinion.
I'll try to describe what I mean. I'll start with Schumacher:

Art was the coordinator of his dive team (like you)
and he too had considerable diving experience;
his highest rating was "divemaster" and he held
the rank of Assistant Chief. Art was a public
safety diver who died at age 46 wearing a
nylon chest harness with a nylon rope attached
to his chest harness via a locking carabiner.

Art and his team members were dispatched to a
report of a vehicle in a rain swollen creek.
When they arrived, the vehicle had already come
to rest against a culvert pipe passing beneath
County Road 42 in Medina County, OH. It was cold
and early in the morning and they arrived on scene
around 4 AM. Art made a decision to enter the water.

He was "only going to check under the car and
along the side" one teammate stated.

Minutes after entering the water, Art was sucked
under the vehicle and into a culvert pipe that
was 5 feet in diameter. There were no line pull
signals since the search line had been pulled
taunt against the underside of the vehicle. A
few minutes after entering the water, team
members knew Art had a problem. The search
line was pinned under the vehicle so they could
not give slack allowing Art to exit the pipe
on the down current side. The vehicle was
removed via a wrecker and at 0520 hours, Art
Schumacher's body was pulled from the culvert
pipe. Art was still wearing his chest harness,
nylon rope and locking carabiner, and a dive
knife. Additionally, he had 2400 psi in his
SCUBA cylinder and his regulator functioned
normally; his mask was still in place. A senior
company officer, well trained, with considerable
experience died because he could not release
himself from his search line and exit on the
down stream side of the culvert pipe. He was
less than 25 feet and 5 seconds from the pipe exit.

1 - "the vehicle had already come to rest against a culvert pipe"
This may suggest that the current was significant to move the vehicle into a dangerous area. If it could suck a vehicle up against it it could certainly take a diver.
We have a rule; no diving around intakes or outflows unless they can be (and are) shut off.

2 - 'He was "only going to check under the car and along the side" one teammate stated'.
If the plan was to search UNDER the car it should have been realized that direct line access will almost certainly be compromised. Communication to the surface MUST be maintained. One method when working around vehicles is to deploy a 2nd diver to act as an in water tender so that access is maintained. This obviously requires significant training and practice.
Never place a diver anyplace where he doesn't have direct line access -- certainly don't plan to do it!

3 - "A few minutes after entering the water, team members knew Art had a problem"
Goes along with the direct line access thing again but in case it was to happen by accident, the surface should be proficient enough to react instantly when they loose contact; not in a few minutes

4 - "he had 2400 psi in his SCUBA cylinder and his regulator functioned normally; his mask was still in place"
This may suggest that he may have lost his regulator and didn't have the skills to either retrieve it or access his back-up. These are primary skills that should reqiure no equipment crutch to accomplish OR
More then likely, my guess would be that he was knocked unconcious when he was sucked under the car (or shortly after - maybe banging into the sides of the culvert?) - good argument for a FFM but even more of an argument that this dive shouldn't have been done. If he was unconcious, a biner or a shackle would make no difference

5 - "...died because he could not release himself from his search line and exit on the
down stream side of the culvert pipe"
Maybe. But, I believe the above points lead to his death far before the option to release the tether even comes up. This also assumes that he would be properly trained and practiced in the use of the shackle. His knife was still in place so he wasn't thinking of release with that method or the knife would've been out, why would using a shackle be any different?

What's to say that the release would allow the diver to reach the exit? He could get tangled and trapped inside and with no tether there is little hope of finding him if there's significant debris as there often is during flooding (it could take weeks to get someone out of that!)
What's to say that the diver would be able to surface even if he did make the exit? Again, now a search for the lost diver is required.
What if the culvert is hundereds of feet long?

I'm being very critical of the incident and I believe that we all should so as to learn from it. I'm not saying I have all the answers. I'm sure there's more to the story than this and some of the precautions that I would take MAY have been taken, I'm only going by what is here.

Here's a question I think we should be asking:
Would the use of a quick release shackle have made this dive safe?
I don't believe it would by a long shot. Even the best trained diver in the world will have limits. I believe the skills, training and procedures that were used far exceeded what this diver (and perhaps any diver) was capable of.

Thanks for posting it.

Anyone else see anything more to this?

 

[bridgediver]

I'll try not to be so wordy with the others. The theme remains...

Hartman:

Charles David Hartman (age 30) was an experienced
public safety diver (police officer) who entered
flowing water wearing SCUBA gear and a search line
attached via a carabiner. He too died when he
could not release from his search line. Teammates
and spectators on site watched him on
the surface for a period of time and didn't know there
was a problem until it was too late. Water currents
caused Officer Hartman's body to move in a life-like
motion and it was only after a short period of
time that personnel on shore realized the seriousness
of the situation.

Not alot here to support one way or the other. I will say that the surface should KNOW the status of the diver all the time. There's no guess work to this whether the current is moving him or not.
Why by being tethered did this guy die? Doesn't say and so the same fate could have occured with a shackle.

Sorry, Blades, I don't think this one counts...

Lastly, Hut:

Frank Hut (age 28) died in the relatively calm waters
of a South Carolina Sound. Frank had submerged,
made a dive, and returned to the surface for
another tank of air. Unfortunately his comm rope
had wrapped under a submerged cable. When wind
shifted the dive boat slightly, he was pulled underwater
with the submerged cable acting as a directional pulley
on his comm rope. Even though team mates responded
promptly, they were unable to save Frank's life.

I'd like to know alot more about this dive's profile. was he low on air when he surfaced (or out)? What is the SOP for a turn pressure? Did he breathe his tanks dry? How was the boat anchored (ie properly secured for dive ops)? Did he have shears to cut the comm rope and did he train with them? How prompt is 'prompt'?

This one is also inconclusive. Dive planning is very suspicious here...

 

[bridgediver]

As you probably know, in the system commonly used here, the back-up diver would only be tethered to his search line and would not be double clipped (connected to the primary diver's search line).


Blades

I do remember, Blades. Try it out next time you're doing a pool session. It'll take quite a bit of practice as the divers need to be aware of the lines to avoid getting crossed up (as you could imagine, hence pool first suggested). But even if they are hopelessly tangled all the tangles will lead to the tenders

 

[Snowbear]

First of all - thank you Blades, for starting this thread (both here and on the Firehouse.com forum) as it makes us all think about these thing more. LODD is something none of us wants to face and something we are working every day to avoid.

Furthermore, our organization does not believe it is going to resolve every situation where a search line is fouled on the bottom. What we do want though is an opportunity for divers to have sound options available to them. It is apparent that using knives and cutting shears (fine motor skills) when the diver is beginning to panic does not work in every situation. "Lack of a cutting tool" was never cited as a factor in any of the PSD "entanglement" fatalities we researched.

Other than the situations in which the divers should not have entered the water in the first place (like the car in the siphon), what situations of fouled search lines are not solvable by contingencies?

As bridgediver noted, the times and depth limits for non-commercial PSD dive teams are such that even with 'extensions' there should be more than enough time to sort out a problem. The only REAL life-threatening emergency is running out of air. With proper and trained-for contingencies, this emergency is easily avoidable and time is bought for sorting out entanglements.

When "$#!t hits the fan" we believe divers should have quick options that will likely save their lives. Certainly, all divers should be trained in risk/benefit analysis and understand the "pros" and the "cons" for every system.

Like what? What situation would require a PSD diver to have 'quick options' including the need to release from the primary search line rather than wait for the backup diver? Again, as long as there's air to breath, everything else can be sorted through.

As it relates specifically to the "quick release snap shackle" we believe 13% of the PSDs who drowned, because their search lines became fouled on the bottom, would be alive today had they had an option and they had released the search line system.

In the examples you've cited, it seems that in most cases, a workable contingency plan as well as proper training would have done more for these divers than a quick release shackle that a paniced diver may or may not remember to release.

From the LODD data, we believe not every diver will be able to activate the release on the snap shackle. We also believe divers are going to continue to make mistakes. Some may hook into the system improperly, some may release out of the system at inopportune times, some may be fouled in their search line, fishing lines and nets (at the same time).

So rather than add this piece of equipment, which may in rare cases be of benefit, but also may provide false sense of security - or more often, inappropriate release from the primary search line in black water - how about planning for and training for dealing with these entanglements?

 

[BladesRobinson]

What's to say that the release would allow the diver to reach the exit? He could get tangled and trapped inside and with no tether there is little hope of finding him if there's significant debris as there often is during flooding (it could take weeks to get someone out of that!)
What's to say that the diver would be able to surface even if he did make the exit? Again, now a search for the lost diver is required.
What if the culvert is hundereds of feet long?

The Quick Release Snap Shackle is the option of LAST resort. If we were to say the diver in distress had a 50/50 chance to survive(using the QRSS), isn't that better than ZERO?

In a three story building there is a likelihood that jumping from the top floor will result in death. If you are in the top floor apartment when the room flashes over and the face piece has melted away from your face and the fabric on your bunker coat is charred and cracking, do you go through 50 feet of flames trying to reach the hallway (which may be envolved too), or do you jump out the window that is an arm length away?

For Public Safety Divers, the Quick Release Snap Shackle can be the window of opportunity needed to survive an incident that is responsible for 13% of the PSD deaths; search line entanglement.

We can debate that in a perfect world, firefighters should vent all buildings to prevent the buildup of fire gasses. In a perfect world we would have ladders preplaced at all windows. In a perfect world we would never allow a diver's search line to get fouled, visibility would be greater than 50' and the waters would be warm. Unfortunately our world is not always perfect though.

As it relates to the Quick Release Snap Shackle, many believe that the benefits far outweigh the risks.


In the scenario quoted above ...it could take weeks to get someone out of that!. I say, "Yeah ... it could."
For me, I am going to be more upset that a brother PSD was killed in the line of duty as opposed to how fast his body could be recovered.

A point to ponder ... if we don't trust a diver to make good decisions and get himself out of danger, why do we allow him to carry knives/shears/etc? Should these cutting tools only be worn by the safety diver?

The Quick Release Snap Shackle is a tool of last resort that can assist a diver by rapidly mitigating search line entanglement.

Blades

 

[BladesRobinson]

...It'll take quite a bit of practice as the divers need to be aware of the lines to avoid getting crossed up (as you could imagine, hence pool first suggested). But even if they are hopelessly tangled all the tangles will lead to the tenders

Yep, that is exactly the way I imagined it....

I am surprised you really believe the extra line increases PSD safety.

I try hard to keep an open mind but when I've practiced similar scenarios (without the extra line), no one has ended up "hopelessly tangled" and the drill is faster and, I believe, more efficient. You mention that "all the tangles lead to the tenders," but the way I interpret your scenario, at least one of the tangles leads to the other diver.

There are times when KISS is better and extra equipment is worse. I think this is one of those times.

Blades