Recently my inner child took notice of a circle of light racing across the cloud tops as I cruised at 7000 feet and 180 mph with the prevailing westerlies at my back. I was headed east above the Gulf Coast between New Orleans and the Florida Panhandle, and the late afternoon sun crept ever lower behind my right wing. Like a fighter in loose formation, the ring of colored light was keeping pace with the aircraft, just in front of my left wing.
My adult self realized that the spot contained a shadow of the airplane, but the bright halos around the dark shadow puzzled me. When my inner child asked me what it was, I had no ready answer.
I’d seen those halos before without really understanding them, but now I had a chance to photograph them. I grabbed cameras and recorded the beautiful phenomenon while the autopilot kept the aircraft on course.
One of the advantages of general aviation aircraft is that we often fly at the altitudes of the DC3s, the early airliners. Which meant that at 7000 feet I could open a small window beside me without depressurizing the cabin and give the camera a clear view of what I was experiencing.
An understanding of what I was seeing would have to wait.
[youtube id=”sV90o44sCE8″ w=”700″ h=”600″]
With few exceptions, Glories remain in the realm of pilots and Angels. By association, many pilots feel privileged to see a glory. I know I do.
Without knowing the science behind glories, pilots may even interpret them as signs of the divine. After all, they do look suspiciously like halos seen in medieval religious art. Indeed, “glory” is another name for those iconic halos.
Science is only able to partly demystify the subject of glories. The best technical explanation is that glories are the result of reflections (back-scattering) of sunlight coming from directly behind the observer. The tiny spherical water drops in clouds are the objects that scatter the sun light. Oddly enough, the size of the water droplets determines the size of the glory, which by the way may contain multiple rings as seen on the videos in this posting.
MiePlot simulation of scattering of sunlight from r = 4.8 µm water drops superimposed on a digital image of a glory taken from a commercial aircraft. From philiplaven.com.
This process of ring formation from water droplets is called Mie Scattering, and is described mathematically by Mie Theory. Phillip Laven’s website, http://www.philiplaven.com/index1.html, provides an ample resource for the curious.
Glories have proven to be such an elusive quarry, that I, like many pilots, have developed a fascination with them. Therefore I could not resist making a brief video, with music, of the glories encountered on that one eastward flight. In it you see a classical glory, followed by a fleeting and hard to photograph glory on the side of a cloud, followed by apparent flight into an ever moving cloudbow.
Suppose you find yourself on an alien planet, battling with indigenous species. On your side, you have smarts, both natural and technological. The alien defenders have nothing; no technology. Well, they do have slime, but that’s all.
Brains against the brainless: Who do you think will win?
Blithely headed into tick-infested woods.
I spent a summer weekend with my family in a cabin in the Virginia mountains a few years ago. It was nature at its finest, until we discovered after a short walk in the woods that ticks seemingly rained down upon us and were invading our bodies as fast as their little legs could move. We were food, and they were hungry. Human-sized meals didn’t come around those woods very often, apparently.
The entire family, adults and children, stripped down to our underwear on the porch of the cabin, trying to rid ourselves of the invaders. Modesty took second place to the fear of miniature arachnids.
Once the imagined itching had abated and the baby was asleep, we soothed our nerves with puzzles and games, or reading from a well-stocked bookshelf. I picked a book with an interesting cover; it was John Scalzi’s Old Man’s War.
I cannot say enough good things about Scalzi’s debut novel, a futuristic science fiction, other worlds story. Suffice it to say, it features combat between Earthling soldiers and all sorts of bizarre and ruthless alien life forms. Although Scalzi didn’t write about invading armies of ticks, per se, I could easily envision such a terrifying encounter.
This author devouring Scalzi’s “Old Man’s War”.
I also think and write about extraterrestrial aliens. Like most writers, I assume ETs are sentient, and calculating. Depending upon the writer, those ETs may have either high morals, or no morals at all, but they always have a brain.
Lately, I’ve had to rethink potential plot elements dealing with intelligent life forms. The reason is, scientists now claim that a single celled animal, a slime mold, acts with a shocking degree of intelligence. The kicker is, being a single celled organism, slime mold does not have a brain.
Slime mold knows a good thing when it finds it. (Photo credit: SB_Johnny)
Intelligence without a brain?
Compared to slime mold, ticks are geniuses if we count the gray matter cells contained in their single-minded heads. However, according to a Japanese researcher the brainless slime mold can solve problems even scores of engineers could not easily solve.
Sounds like science fiction to me.
So now imagine the following storyline. Your spaceship lands on a verdant planet that has no higher, brain-possessing life forms, at all. However, what it does have in abundance is slime mold. And of course the threat from slime mold is easy to ignore — until it is too late. The mindless protoplasm senses all sources of food, and fans out in all directions, following the scent.
The ship’s science officer tries to warn the mission commander, but the arrogant and miscalculating commander responds with a volley of lead rounds into the nearest slime; which of course is not in the least bit deterred from its food-finding task.
And when the crew sleeps, as of course they must, the brainless mold finds the food sources, one by one, absorbing the human nutrients.
Human-sized meals don’t come around those woods very often, apparently.
Being brainless, slime mold cannot be considered cunning. But, one could argue, it’s not stupid either: it can’t be tricked. It is, if anything, relentless.
From a cinematic perspective this is not an entirely new theme. The 1958 movie The Blob starring Steve McQueen popularized the idea of mindless organisms devouring humans. But at that time there was no real science behind it. Now there is.
Some interesting science facts about slime mold are found in this link and the following Scientific American – NOVA video.
A Closed Circuit Rebreather diver in a Florida spring.
In technical or recreational rebreather diving, safety is a matter of personal choice. Wrong choices can turn deadly.
Some poor choices are made for expediency, while others are made with the best of intentions but based on faulty or incomplete information. As a diving professional, it is those latter choices that concern me the most.
David Shaw
A poignant and well documented diving fatality involved a record setting Australian diver, David Shaw. David was an Air Bus pilot for Cathay Pacific.
Professional pilots are immersed in a culture of safety, a culture that makes airline travel the surest means of long distance transport. David applied that same sort of attention to his diving, recording on his personal web site his detailed plans for a record setting dive to recover the body of a diver who died in the 890 feet (271 meter) deep Boemansgat Cave of South Africa 10-years prior to David’s ill-fated dive.
Despite his extensive preparations, David Shaw made a fatal mistake. Like those who fail to appreciate the threat of an approaching hurricane, David failed to recognize the risk of really deep diving with a rebreather.
Unlike other types of underwater breathing equipment, a rebreather is entirely breath powered. That means you must force gas entirely through the “breathing loop” with the power of your respiratory muscles. On a dive to 890 feet, you are exposed to 28 times normal pressure, and breathing gas more than five times denser than normal. The effort involved is enough to dismay some U.S. Navy divers at depths far less than David Shaw intended to dive. Yet in David’s own words, he had previously never had a problem with the effort of breathing.
“The Mk15.5 (rebreather) breathes beautifully at any depth. WOB (work of breathing) has never been an issue for me. Remember that when at extreme depth I am breathing a very high helium mixture though, which will reduce the gas density problem to a certain extent.”
He goes on to say, “I always use the best quality, fine-grained absorbent on major dives. The extra expense is worth it.”
“I have had 9:40 (9 hrs, 40 min duration) out of the canister and felt it still had more time available, but one needs to qualify that statement with a few other facts. Most of the time on a big dive I am laying quietly on deco (decompression), producing minimal CO2 (carbon dioxide).
In those words lie a prescription for disaster.
A rebreather scrubber canister containing granular absorbent through which a diver has to breathe.
David wanted to use a single rebreather that would accomplish two tasks — provide a long duration gas supply and CO2 absorbing capability for a dive lasting over nine hours, and provide a low work of breathing so he could ventilate adequately at the deepest depth. To ensure the “scrubber canister” would last as long as possible, he chose the finest grain size, most expensive sodalime available. His thought was, that was the best available.
Arguably, the two aims are incompatible. He could not have both a long duration sodalime fill and low breathing resistance.
Cartoon of breathing through a scrubber canister.
As illustrated in a previous blog posting, the smaller the size of granules you’re breathing through, the harder it is to breathe. Think of breathing through a child’s ball pit versus breathing through sand.
Perhaps if David had maintained a resting work rate throughout the deepest portion of his fatal dive, he might have had a chance of survival. After all, he had done it before.
But the unexpected happens. He became fouled and was working far harder to maintain control of the situation than he had anticipated. That meant his need to ventilate, to blow off carbon dioxide from his body, increased precipitously.
A sure sign of high breathing effort is that you cannot ventilate as much as is necessary to keep a safe level of carbon dioxide in your blood stream. CO2, which is highly toxic, can build rapidly in your blood, soon leading to unconsciousness. From the videotaped record, that is exactly what happened.
Purer A, Deason GA, Hammonds BH, Nuckols ML. The effects of pressure and particle size on CO2 absorption characteristics of High-Performance Sodasorb. Naval Coastal Systems Center Tech. Manual 349-82, 1982. (Click for larger image.)
Had David been fully aware of the insidious nature of carbon dioxide intoxication from under breathing (hypoventilating), he probably would have chosen an alternative method to conduct the dive.
One alternative would be to use a larger granule size absorbent in a rebreather at considerable depth (say, 100 meters and deeper), and reserve the fine-grain absorbent for use in a separate rebreather shallower than 100 meters.
David chose the fine-grain absorbent because of the longer dive duration it made possible. Although fine grains are more difficult to breathe through than large grain absorbent, fine grain absorbent lasts longer than large grain absorbent.
But that long duration is only needed during decompression which is accomplished far shallower than the deep portions of the dive. The time spent deep where work of breathing is a threat is quite short. He did not need the capabilities of a long duration, fine grain absorbent.
From the U.S. Navy experience, there are other problems with this dive which might have hastened the end result. A rapid and deep descent causes the oxygen pressure within the rebreather to climb to potentially dangerous levels; a phenomenon called oxygen overshoot. Thus he might have been affected somewhat by oxygen toxicity. A rapid descent might also have induced the High Pressure Nervous Syndrome which would affect manual dexterity.
While those contributing factors are speculative and not evident on the tape, the certainty of the physics of dense gas flow through granular chemical absorbent beds is an unavoidable fact.
No doubt, many have offered opinions on what caused David’s accident. I certainly do not claim to be intimately involved in all the details, nor familiar with all the theories offered to date. Nevertheless, David’s mistaken belief that using the “best absorbent” was the best thing for his dive, is a mistake that needs to be explained and communicated before this accident is repeated with a different diver in some other deep and dark place.
I sat on the edge of a ball pit at Chuck E. Cheeses, calipers in hand, measuring the diameters of a random sampling of plastic balls within the pit.
I suppose I stood out, an officious-looking adult wielding a precision instrument in a place designed for fun. So much so that a father attending his child asked me what I was doing.
I was measuring the ball sizes. I explained that if the balls were too small, and a child became covered with them, then the void space around the balls, the contorted empty volumes that represented places where air can be exchanged, would be too small, making breathing difficult. That made sense to the father, and he seemed pleased that I was looking after his child’s safety.
A child is almost completely covered by balls. A single hand is sticking out, and part of a face can be seen.
Contrary to the way it seemed, I was not a corporate inspector for Chuck E. Cheeses. I was also not a government inspector. But I was curious, gaining information for ideas I was developing about the breathing resistance imposed by particles of various sizes. I was acting, as it were, as a freelance scientist investigating flow through porous beds.
Consider the circumstance where a person is forced to breathe through a mass of balls, as in the illustration below. You can see, better than in the case of the ball pit, that if the balls become too small, or smaller balls fill in the void spaces between larger balls, then the person would be at risk for suffocation.
copyright John R. Clarke.
Advertisements for balls sold for ball pits point out the safety advantage of larger balls for children under age 3. The smaller children are obviously more susceptible to tunneling deeper into a pit of balls, some of which may be piled to two feet or deeper depths.
Balls of 3.1 in. diameter are touted as being ideal for three-year-olds, whereas other popular sizes [2.5 in. (65 mm), 2.75 in. (70 mm)] are not. The 3.1 in. ball is almost twice as large, in terms of actual volume, as the 2.5 in. balls.
A problem awaits a child if the ball pit has poorly sorted ball sizes, especially a mixture of larger and small balls. As shown in the figure to the right, well-sorted balls provide a porosity (airspace for breathing) of over 32%, whereas a mixture with balls fitting into the void spaces between larger balls can reduce void space down to about 12%. That would not be a good plan for a ball pit.
It also is not a good plan for the Namib mole.
The Namib Golden Mole is found in one region of Namibia because of the peculiar characteristics of the sand in that area. The sand grains are surprisingly homogeneous in size, and as the illustration to the right shows, similarly sized particles have a relatively large porosity. For the mole that means that when they burrow deep into the sand to escape blistering noonday heat, they will not suffocate. They can breathe through the sand.
If the sand were of mixed grain sizes, which is more typical of sand dunes, then porosity would be low and the mole would not be able to burrow deep enough to avoid the African heat without suffocating.
So, quite unexpectedly there is a connection between the uniform size of plastic balls in a ball pit and the survival of a mole in a faraway African desert.
You never know where scientific curiosity will lead you.
As will be shown in an upcoming blog post, the topic of breathing through porosities in packed beds is relevant to diving with rebreathers or breathing through chemical absorbent cartridges in gas masks.
While watching an “Ice Pilots” episode on the Weather Channel I heard a pilot of a Curtiss C-46 Commando talking to his inexperienced copilot during a flight. At one point he said they were “making fuel.”
I have enough common sense and experience as a pilot to know that could not be literally true. But I had no idea what the Ice Pilot’s comment really meant until recently returning home during a non-stop flight from Dallas, Texas to the Florida Panhandle.
I had purposefully climbed to 11,000 feet to catch good tailwinds heading east. The winds were even stronger at higher altitudes, but if I’d climbed to the next allowed altitude, 13,000 feet, my passenger and I would have needed to wear an oxygen mask. And I’d left the oxygen system at home.
During flight planning before departure, it looked as if going high would give us enough of a tailwind that we would be able to make the trip without a time consuming fuel stop.
Modern aircraft often have fuel computers communicating with the aircraft GPS navigation system. Fuel computers track every ounce of fuel burned during taxi and flight. The pilot programs the total fuel available and then the fuel computer checks with the GPS to see how many miles remain to the destination, and the ground speed. Every few seconds the pilot sees an update of the fuel burned, gallons remaining, predicted flight time available, the fuel required to reach the destination, and the bottom line, the predicted fuel reserve at the destination.
Typically, I want to land with no less than 10 usable gallons remaining, which is enough to remain aloft for an additional hour at the normal fuel consumption rate. If the weather is bad at the destination, then the required fuel reserve is considerably larger.
On the first phase of my flight to Dallas, once I had reached cruising altitude the fuel computer calculated that if the current ground speed and fuel burn were to continue to the end of the trip, I would have five gallons of fuel left at the destination. That is not enough for safe flight, so a refueling stop was looking inevitable. As the flight continued, the estimation of reserve fuel barely budged from its first estimate. In other words, nothing was changing, and the decision to refuel was firmly made.
East Texas from 11,000 ft. Click to enlarge.
On the return flight, however, flying relatively high where the prevailing westerlies were strong, the computed reserves (RES) were changing. They were growing. As the flight progressed I watched the estimated fuel reserve rise slowly from 8 gallons to 9, then 10, and finally 11.4 gallons. By the time we landed we had 12 gallons of fuel remaining in the two fuel tanks.
It truly looked like we were making fuel.
We weren’t, of course. The reality of it was that the tailwind was increasing in our favor for the east-bound trip. But the fuel computer gave every impression that for every gallon of fuel we burned, we were getting a little bit back.
I finally understand what the Ice Pilot meant; I think. If I ever meet him, I’ll ask.
Thank-you for contacting Cosmic Capacity Corporation’s FAQ regarding our popular Personal Black Hole Product.
1. The price of your product seems astronomical. Will there be equally large maintenance fees?
As they say, if you have to ask, you can’t afford it. But keep in mind, science has shown that if your PBH is not properly maintained it will disappear due to Hawking radiation.
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It is microscopic. That is the only way to make sure the PBH remains safe for the environment. And of course, CCC is an environmentally mindful enterprise.
3. I need the highest level of security for shredding sensitive documents. Will the PBH provide that?
There is no higher security. Once in, there is no coming out.
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You can within reason. Too much garbage input will cause uncontrolled growth of the Black Hole, and as you must understand, that would be undesirable.
5. The hardware front-in to the PBH supposedly limits the amount of feeding of the PBH I can do. Is that hardware reliable, and can it be defeated?
Any attempts to defeat it will cause a transitory swelling of the PBH, just enough to consume whatever is attempting to tamper with the device. Again, physics dictate that the swelling will be both limited and transient. Of course the device will be consumed in the process and your investment will be lost.
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CC Corp has to be satisfied that criminal elements are not purchasing our equipment for nefarious purposes, such as body and evidence disposal. While our device is obviously ideal for that purpose, we would be negligent to not screen, within the limits of the law, all potential customers.
7. If say, a government entity, were to use your device to dispose of weapons and munitions, would that process be safe?
The physically catastrophic events occurring at the event horizon make safe any material entering it. For Explosive Ordnance Disposal (EOD) questions, please contact our military sales representative.
8. I have heard that black holes may spawn other universes. If so, are there security concerns associated with that?
Well, as they say, “Garbage in, garbage out.” But security should not be your concern. Any universe spawned by human waste or discarded items is unlikely to be suitable for life as we know it.
9. The bullet riddled body of my traitorous Uncle Harry is unlikely to become a star or something on the other side. Right?
With a sardonic sneer typical of the glistening-haired, easily-bored waiters in upper crust restaurants, he poked a neatly manicured finger into my menu. “It’s right there. You chose carbon dioxide or methane.”
Even though that conversation is imaginary, it is true, apparently, that in certain parts of the country where fracking is popular for extracting natural gas from the ground, there is some risk of that gas being forced into aquifers feeding wells intended to provide potable water.
Obviously water infiltrated with dissolved methane should not be used for cooking on gas stoves. I don’t need to explain the consequences.
And no doubt, drinking methane containing water could turn the high-school males’ risky game of flatus ignition into a pyrotechnic event competing favorably with the energy release of flaming napalm.
Although the Environmental Protection Agency seems to be silent on the issue, the AMA has recently posted their concern about fracking, for medical reasons. Not all of those reasons are proctological in nature.
Having been an observer and worker within the medical science community for many years, I have only two thoughts that might cheer the energy industry.
The first is that sometimes the medical community makes an issue of things that the human body produces, like cholesterol. Cholesterol is vital for a healthy nervous system. In fact, it is so important that the body makes it, just to make sure it has enough. So why do I have to deprive myself of dietary cholesterol which accompanies the finest food in the world; like lobster, fried fish, and filet mignon? Because supposedly it’s bad for me. That’s what they say, even though my body is producing prodigious amounts to keep itself healthy. Non sequitur is the phrase that comes to mind.
I have nothing against physicians. My father was one, as is my son. Some of my best friends are physicians; and one of them alerted me to this news item. Arguably, physicians have even saved my life.
As the son of a physician I grew up reading the Journal of the American Medical Association … which was almost as entertaining to a young boy as National Geographic. But I don’t understand the profession’s concern for methane in water. After all, methane is colorless and odorless, and does not react with biological systems. What goes in, comes out, unperturbed.
Like cholesterol, the human body produces methane. Methane is produced by bacteria in the gut (so-called methanogens) whose sole purpose is to live well and prosper in the low oxygen environment of the large intestine, and as a byproduct of that anaerobic life style, produce methane. Methane now actually seems to have some purpose in the gut; it stimulates the human immune system. So, apparently, it has a biological purpose. Without it, one could argue, we would literally get sick.
OK, there you have it: my two thoughts that might cheer the energy industry.
But since I don’t anticipate a check coming in the mail from the gas companies, now I’ll share my scientific opinion, of sorts. I once was a fellow in the Water Resources Management Training program at Georgia Tech. (Curiously, the director of the program was named Dr. Carl Kindswater, presumably originally Kindswasser. In German, Wasser is water, and best I can tell, Kindswasser is amniotic fluid. So in a sense it is truly water of children.)
I honestly don’t know if the ironically named Program Director spoke German or not, but I suspect that if he did, he might respond thusly to the story of fracking product found in our precious, and clearly mismanaged, fresh-water supplies.
“Sind Sie aus Ihrem brennenden Geist?”
According to Google, that would mean, “Are you out of your flaming mind?” Somehow, that phrase seems entirely appropriate.
By the way, I always take water without gas, just in case.
I admit it, my early training in physics has made me irritatingly sensitive to the principle of parsimony.
Parsimony, pronounced similarly to “alimony”, can be summed up by the following: the simplest approach to understanding nature should be considered before contemplating a more complicated line of reasoning. In a famous example, it is more probable that planets, including the Earth, orbit around the sun than the visible planets and the sun orbit around the Earth. Of course, in a different time that probability was not obvious to the common man. But then they hadn’t been thinking about parsimony.
Thank-goodness someone (Nicolaus Copernicus) did.
In the search for habitable exoplanets (planets outside of our solar system), the following statement was recently made by astronomer Steve Vogt in response to a storm of skepticism about a potentially habitable planet. “I do believe that the all-circular-orbits solution is the most defensible and credible,” he said. “For all the reasons I explain in detail … it wins on account of dynamic stability, goodness-of-fit, and the principle of parsimony (Occam’s Razor; in Latin, lex parsimoniae).”
William of Occam (also Ockham) was an English theologian of the 14th century. He did not invent the premise behind his razor, but he famously used it to slice through the complicated philosophies of the day and rebut them by an unfaltering demand for simplicity over complexity.
Photo credit: damianskinner.com
Medical students are taught essentially the same principle, albeit using different words: “When you hear hoof-beats, don’t think of zebras.” Wise physicians know that occasionally zebras do show themselves, but they should not be the first thought when a patient presents with unusual symptoms.
If simplicity is to be generally preferred over complexity, then an example in the diving literature comes to mind. This example annoys me to no end, but I’m slowly coming to terms with it. It is the growing popularity of referring to the respiratory effort required to breathe through a scuba regulator or a closed-circuit underwater breathing apparatus (a rebreather) as work (in joules, J) per tidal volume in liters, L.
When work in joules (J) is divided by volume (L), dimensionally the result is pressure (kiloPascals, kPa). To be exact, what is often called work of breathing in diving is actually the average pressure exerted by a person over the entire volume of a breath. The principal of parsimony says that if it is a pressure, if it has units of pressure, then we should call it a pressure (kPa) and not something more complicated, such as Work of Breathing specified with units of J/L.
The light grey ellipsoidal area within this pressure-volume loop is equal to the work (J) of breathing for that breath.
(Examples in the regulatory diving literature correctly using Work of Breathing with units of joules can be found in early editions of NATO STANAG 1410. EN250:2000 is an example using the units of J/L for work.)
I find in my dealings with non-respiratory physiologists, that the concept of work of breathing is difficult to grasp since mathematically it involves a definite integral of pressure over a change in volume. I have made various attempts to simplify the concept, but I still find knowledgeable medical professionals misunderstanding it. In fact, mathematical integrals seem to be as frightening to most physicians as poorly dissected cadavers would be to laymen. Even engineers who certainly should grasp the intricacies of work and power end up confused.
I’m sure it adds to the confusion when some diving physiologists speak in quotients. For example, since a cubit is a length of 48 cm, and a hectare is 2.47105 acres, you could describe a person’s height as 165,400 cubic cubits/hectare. Dimensionally, that would be correct for a six foot (1.8 m) tall individual. However, most people would prefer the units of feet or meters rather than cubic cubits per hectare. Certainly, the simpler description is far more parsimonious than the former.
The shaded area within this triangle is equal to the “Work” inside the previous P-V loop. By dividing by tidal volume, you obtain the average mouth pressure on the vertical axis.
For the same reason, it makes more sense to speak of a descriptor with units of pressure as simply pressure (kPa) rather than a quotient of work per liter (Joules/L).
If describing a simple parameter like pressure as a quotient is not defensible scientifically, is it defensible psychologically?
Maybe. The U.S. Navy has used terms like “resistive effort” to convey the impression that a volume-averaged pressure is something that can be sensed by a diver. To breathe, divers have to generate a pressure in their chest, and that pressure generation requires effort.
“Effort” is admittedly not a hard-science term: it doesn’t even pretend to be. However, the use of “Work of Breathing” connotes hard science; the concept of work is pure physics. But as I have shown, the way it is increasingly used in diving is not pure physics at all. So its use is misleading in the eyes of a purist, and undoubtedly confusing to a young engineer or physicist.
But to a diver, does it matter? Does it somehow make sense? Do divers care about parsimony?
Well, I have yet to find anyone who does not intuitively understand the notion of the work involved in breathing. If they have asthma, or have tried breathing through a too long snorkel, they sense the work of breathing. So I imagine that the inexactitude of J/L is of no import to divers.
However, I also believe that the over-complication of an arguably simple concept should be just as unappealing to designers of underwater breathing apparatus as it was to William of Occam or, for that matter, the designer of the Cosmos.
Under thick ice in the Ross Sea, near McMurdo, Antarctica.
When scuba diving under 3-m thick polar ice with no easy access to the surface, the last thing you want to worry about is a failure of your scuba regulator, the system that provides air on demand from the aluminum or steel bottle on your back.
However, cold water regulators do fail occasionally by free-flowing, uncontrollably releasing massive amounts of the diver’s precious air supply. When they fail, the second stage regulators, the part held in a scuba diver’s mouth, is often found to be full of ice.
The U.S. Navy uses scuba in polar regions where water temperature is typically -2° C (28° F). That water temperature is beyond cold; it is frigid. Accordingly, the Navy Experimental Diving Unit developed in 1995 a machine-based regulator testing protocol that most would consider extreme. However, that protocol has reliably reflected field diving experience in both Arctic and Antarctic diving regions, for example, in Ny-Ålesund, Svalbard, or under the Ross Sea ice near McMurdo Station.
There are currently both philosophical and quantitative differences between European standards and the U.S. Navy standard for cold water regulator testing. Regulators submitted for a European CE mark for cold water diving must pass the testing requirements specified in European Normative Standard EN 250 January 2000 and EN 250 Annex A1 of May 2006. In EN 250 the water temperature requirement for cold water testing ranges from 2° C to 4° C. Oftentimes, regulators that pass the EN 250 standard do not even come close to passing U.S. Navy testing.
An iced up, highly modified Sherwood SRB3600 Maximus second stage regulator
The Navy’s primary interest is in avoiding regulator free-flow under polar ice. The breathing effort, which is a focal point of the EN 250 standard, is of lesser importance. For instance, the 1991 Sherwood SRB3600 Maximus regulators long used by the U.S. Antarctic program have been highly modified and “detuned” to prevent free-flows. You cannot buy them off-the-shelf. Detuning means they are not as easy to breathe as stock regulators, but they also don’t lose control of air flow to the diver; at least not very often. Here is a photo of one that did lose control.
NEDU performs a survival test on regulators, and any that pass the harshest test are then tested for ease of breathing. The so-called “freeze-up” evaluation breathes the regulator on a breathing machine with warmed (74 ±10°F; 23.3 ±5.6°C) and humidified air (simulating a diver’s exhaled breath) at 198 feet sea water (~6 bar) in 29 ± 1°F (-1.7 ± 0.6°C) water. Testing is at a moderately high ventilation rate of 62.5 L/min maintained for 30 minutes. (In my experience a typical dive duration for a dry-suit equipped diver in Antarctica is 30-40 min.)
To represent polar sea water, the test water is salted to a salinity of 35-40 parts per thousand. The possible development of a “freeze up” of the regulator 2nd stage, indicated by a sustained flow of bubbles from the exhaust port, is determined visually.
In contrast, the European standards call for slightly, but critically, warmer temperatures, and do not specify a duration for testing at an elevated respiratory flow rate. I have watched regulators performing normally under EN 250 test conditions (4° C), but free-flowing in water temperatures approaching 0° C. Those tests were run entirely by a non-U.S. Navy test facility, by non-U.S. personnel, using a U.K. produced breathing machine, with all testing being conducted in a European country. The differences in testing temperatures made a remarkable difference.
Haakon Hop of the Norwegian Polar Institute in Ny-Ålesund, Svalbard.
The NEDU testing results have been validated during field testing by scientific diving professionals under Arctic and Antarctic ice. The same regulators that excel in the NEDU protocol, also excel in the field. Conversely, those that fail NEDU testing fare poorly under the polar ice. For instance, a Norwegian biologist and his team exclusively use Poseidon regulators for their studies of sea life inhabiting the bottom of Arctic ice. (The hard hat in the photo is to protect cold skulls from jagged ice under the ice-pack.) Poseidon produces some of the few U.S. Navy approved cold-water regulators.
As is usual for a science diver in the U.S. Antarctic Program, a friend of mine had fully redundant regulators for his dive deep under Antarctic ice. He was fully prepared for one to fail. As he experienced both those regulator systems failing within seconds of each other, with massive free-flow, he might have been thinking of the words of Roberto “Bob” Palozzi spoken during an Arctic Diving Workshop run by the Smithsonian Scientific Diving program. Those words were: “It’s better to finish your dive before you finish your gas…”
In both NEDU’s and the Smithsonian’s experience, any regulator can fail under polar ice. However, those which have successfully passed U.S. Navy testing are very unlikely to do so.
A diver’s breathing equipment, helmet, gas bottle, umbilicals and buoyancy compensator lie stretched out on the grey concrete floor. The diving gear has a look of sadness about it. Perhaps that equipment will tell a story of why its owner is dead, but usually it does not.
Storm clouds from 30,000 ft. Photo by Wendell Hull.
In another part of the world the NTSB catalogs the fragments of an airplane shredded by the elements and thrown in a heap back to earth. The only good thing to come from an aircraft accident is that usually there are enough clues from wreckage, radio recordings, radar returns and weather reports to piece together a story of the end of life for pilot and passengers.
It’s always the question of “Why?” that drives any investigation.
Perhaps it is the knowing of how death comes, so unexpectedly to surprised souls, that makes it just a little bit easier to make the mental and emotional connection between an interesting moment and a deadly moment. If that is true, and I believe it is, then the telling of such macabre stories can be justified. It is not a telling through morbid interest, but a sincere belief that by examining death closely enough we can somehow force it to keep its distance.
That may be foolish thinking, but humankind seems to have a hunger for it, that esoteric knowledge, so perhaps it is a truism. Perhaps we sense instinctively that the knowing of something makes it less fearsome.
Being a student of diving and diving accidents, I know full well how unexpected events can make you question what is real and what is not, what is normal and what is abnormal. Without practiced calm and reasoning, unexpected events can induce panic, and underwater, panic often leads to death. That is also true for aviation.
The best preventative for panic is a realistic assessment of risk. Risks are additive. For instance, flying in the clouds is accompanied by a slight degree of risk, but with a properly maintained airplane, with a judicious use of backup instruments and power supplies, and with recent and effective training, that risk can be managed. In fact, I delight in flying in clouds; it is never boring, and I know that I am far safer than if I had been driving on two lane roads where the potential for death passes scant feet away every few seconds.
Flying at night is another risk. If something were to go terribly wrong, finding a safe place to land becomes a gamble. On the other hand, seeing and avoiding aircraft at night is simple because of the brilliant strobe lighting which festoons most aircraft. For me, the beauty, peace and calm air of night flight makes it well worth the slight risk.
Garmin NEXRAD Weather display.
Technology has made weather flying safer and, I have to admit, more enjoyable. The combination of GPS driven maps and NEXRAD weather has made it almost impossible to blunder into truly bad weather. During the daytime, my so-called eyeball radar helps to confirm visually what NEXRAD is painting in front of me. If it looks threatening, it probably is.
Unlike aircraft weather radar, virtually every pilot can afford to have NEXRAD weather in the cockpit. And unlike aviation radar, NEXRAD can see behind storms to show the view 100 miles downrange, or more. Having often flown in stormy weather without benefit of NEXRAD, I truly rejoice in the benefits of that technology.
WX 900 Stormscope
I routinely fly with not only NEXRAD, but also a “Storm Scope” that shows me in real time where lightning is ionizing the sky. Those ozone-laced areas are off-limits to wise aviators. But sometimes even a Storm Scope is not enough to keep the willies, or as some call it, your spidey sense, from striking. (Presumably spiders are not particularly cerebral, but they are pretty adept at surviving, at least as a genus and species.)
I was recently flying around stormy weather, carefully avoiding the worst of it, and maneuvered into a position that would provide a straight shot home with yellow tints showing on the weather screen, suggesting at most light to moderate precipitation. I had flown that sort of weather many times; it usually held just enough rain to wet the windshield.
However, my internal risk computer made note of the following factors: we were in the clouds so if weather worsened I wouldn’t see it. Night was approaching which markedly darkened the wet skies we were beginning to enter. The clouds and darkness conspired to make useless my eyeball radar. In addition, the Storm Scope was unusually ambiguous at that moment. I thought it was confirming a safe passage home, but I could not be 100% certain.
On top of that, the FAA recently warned that NEXRAD signals can be considerably more delayed than indicated on the weather display. The device might say the data is 2 min old, but the actual delay could be 10 minutes or more. In other words, the displayed image could be hiding the truth.
Aircraft weather radar.
Planes have been lost because of untimely NEXRAD data. For that reason there is a philosophical difference between NEXRAD and true radar. On board weather radar is said to be a tactical weather penetration aid, and NEXRAD is a strategic avoidance asset. My gut told me that at that moment in airspace and time the boundaries between those two uses, tactical and strategic, were getting fuzzy.
It is times like that when an awareness of the slim margin between a safe flight or dive, and a deadly flight or dive, becomes a survival tool. In this case, I and many other experienced pilots have made the call to turn around and land. Unfortunately, the record and the landscape is littered with the wreckage of those who chose otherwise.
They forgot just how thin the margin of safety can be.
The flight (green line) from Cobb County Regional (KRYY) to Panama City (KECP) was interrupted by a stop at Montgomery AL.
Recently my inner child took notice of a circle of light racing across the cloud tops as I cruised at 7000 feet and 180 mph with the prevailing westerlies at my back. I was headed east above the Gulf Coast between New Orleans and the Florida Panhandle, and the late afternoon sun crept ever lower behind my right wing. Like a fighter in loose formation, the ring of colored light was keeping pace with the aircraft, just in front of my left wing.
