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For those of us who fly the azure skies of New Mexico where even a a "ho-hum" soaring day can produce lift to altitudes in excess of 12,500 feet MSL, supplemental oxygen is a must.
I have many not-so-fond memories of using my military surplus A-13 mask in conjunction with my a-14 regulator...all of which are good to altitudes far in excess of any height above Mean Sea Level to which I care to fly. I can remember donning my soaring chapeau with its velcro ear locks, looking like some aberrant Hasidean who had given up his religious studies in order to pursue a somewhat less pious path. After what seemed like a very short time aloft, my rubber probiscus would cause me to produce enough perspiration that the mask would tend to slide around on my face which would require readjusting the velcro straps. Of course none of this increased my comfort level.
Although the mask contained a mike, whenever I attempted to use it, I sounded as though I was in the bottom of a barrel with a mouth full of marbles. I was reduced to either acknowlegding transmissions with clicks of the mike, or to pulling loose one of the straps in order to complete a communication and then going through the motions of readjusting the contraption. An O2 system which employs a snugly fitted mask is great for flying at altitudes above 18,000 feet MSL, but under what circumstances are we able to do this? Why, in a wave window, of course-or with a dispensation from ATC for special flights. By the middle of last year's soaring season I was determined to convert to some sort of cannula system and had begun investigationg what was available on the market. The obvious choice at the time seemed to be the Nelson Oxygen System .
Sometime around the first part of 1993, David Jones (once-and I hope future-Open Class race pilot) turned me on to a budding company in Salt Lake City that was producing a very compact system which was initially designed for mountain climbers, hangglider and parasail pilots. By now, you probably have seen and read both the March,"New Products" column as well as the letter fom Robert Weien and the repsonse from the EDS designer and maker, Patrick Mclauglin in May, all dealing with the Electronic Delivery System. Now I certainly don't have the technical background or credentials to enter into a discussion of the merits (or lack thereof) of the points raised by Weien: But as Mr. Mclauhlin has stated, he will supply whatever documentation is requested by a prospective buyer. So, let's move on. It is safe to say that Homo Sapiens' respiratory system has remained unchanged for about the last 10,000 or so years. However, our understanding of its function and efficiency has increased exponentially over the last fifteen years. It's also fair to say that oxygen systems have changed very little since WW11. It's only been in the last few years-since about 1987-that the FAA has come to recognize that cannula systems are safe for normal, healthy individuals who do not suffer form any sort of respiratoy distress. Unfortunately, cannula systems are only legal up to 18,000ft. MSL (which goes hand-in-hand with the point I raised earlier about the restrictions on soaring flight above that altitude).
As Patrick Mclaughlin has stated in the EDS rebuttal, his system was developed by virtue of research conducted by Teip, Brooke, Carter and Phillips during the 1980's. In any case, I feel that the information provided to me by Mountain High Equipment Supply, Patrick's company clearly documents the safety aspects of their system, but acceptance of this information may require individuals who are steeped in our dated information and/or technology. After reading the pamphlet provided about the Electronic Delivery System, one realizes that it is a fuction of pressure altitude as determined by the temperature-compensated barometer within the EDS. As the recipient of the burst of O2, you and I then become the diluter by virtue of the remaining portion of our inhalation.
One of the points I've noted when using the EDS is that it knows when I'm breathing even when I do it through both my mouth and nose.As soon as the system senses that I am taking a breath, I can hear something inside the little black box go "click", and if I choose to look at it, I can see the green blinker light do its thing. Very shortly thereafter I hear a "phiett" sound as I receive a bolus, or pulse of O2. The salient points of Patrick's design as I understand it, are not that you are now required to make fewer trips to the dude whom you pay to pass gas (ok, ok...from the guy who peddles the oxygen), but that the system, a; Does not waste your O2 supply, and b; Does provide you with a more ample supply of supplemental oxygen as pressure altitude increases. The system also has a self-test mode which it cycles through when you turn it on. By selecting the "N" (or "Night") mode while on the ground, it is possible to perform an additional functional test. The battery has a "press to test" button which gives one a more that ample warning of pending battery failure. This brings up the point of what to do if the battery should poop out while bumping along just below Flight Level 180. I look at it this way: First, I have more that ample time to make a "divebrakesopen" descent to somewhere between 14,000 and 12,500 feet MSL, where I'm legal to fly without supplemental oxygen for up to one-half hour (FAR 91.211.) Second, I have more than ample time to replace the battery before I start getting really stupid (read "hypoxic").
As David Jones pointed out to me, another plus for the "N" mode is that if you feel that you would like to enrich the supply of O2 to your tired headbone while on final glide while you are below 11,500, you can swich to the "N" mode and freshen up.
In order to adapt to the EDS to by Discus I asked Patrick if he would make up a 36" flexible high pressure line which would run from my present 22cu.ft. bottle to the bulkhead below my right shoulder where the "Shreidera" filler valve have been located. On the end of the line (see photo 1) you can see the brass fixture on which the pressure gauge is mounted as well as the regulator. George Applebay of Zuni-fame machined an aluminum block into which the brass fixture is bolted and in turn attatched to the bulkhead. Photo 2 shows the EDS installed directly below the old mounting brackets for the A-14. Its position allows me to both hear and see the system as it functions. Photo 3 shows just how little space the entire system uses, and photo 4 shows that the EDS can readily be used with a Plantronics headset wearing the ball cap at half lock is optional). Is the EDS for everyone? Depends on the what kind of flying you do. At the very least it should appeal to pilots of at least one branch of the service (attention all former Nasal Aviators). It's safe to say that the EDS will neither improve my sex life nor make me a better pilot...but it's sure to make me a more comfortable and contented one! (1992 A Breath Of Fresh Air by Billy Hill)