Aeromedix Flight Blog
Flying, Medicine and Everything Inbetween
This month has seen two tragic accidents that involve pilot incapacitation at high altitudes. While it’s impossible to say for certain that hypoxia was the primary cause, both mishaps, flight profiles, and the reports from the military pilots who intercepted the aircraft point toward this as a possibility. Unlike our military counterparts, most General Aviation (GA) pilots have not undergone high altitude training in a hypobaric chamber or used a Reduced Oxygen Breathing Device (ROBD) to learn hypoxia symptom recognition. As a quick reminder, here are some of the typical symptoms of hypoxia:• Cyanosis (blue fingernails and lips)• Headache• Hot flashes or a feeling of warmth• Decreased reaction time• Impaired judgment• Euphoria• Visual impairment, reduced visual acuityEven though these are the most common symptoms each pilot’s physiological responses are unique. With the insidious nature of hypoxia and the resulting loss of cognitive abilities, it quickly becomes difficult to recognize the symptoms in time to take prompt action and mitigate the risks of becoming incapacitated while flying.The good news is that GA pilots have a powerful low cost tool available to them to help avoid succumbing to the effects of hypoxia. A pulse oximeter is the best defense against hypoxia and can be purchased from a variety of aviation vendors or any drug store.When flying an unpressurized aircraft pilots should check their oxygen saturation levels regularly (about every 10-15 minutes). In a pressurized aircraft, pilots should use the pulse oximeter as needed or if they experience the first symptoms of hypoxia. Cabin pressurization problems and hypoxia are serious emergencies. Communicating this to ATC and the use of supplemental oxygen, if available, is imperative.It is also important to remember that each pilot’s ability to maintain adequate oxygen levels will be slightly different based on a variety of health and lifestyle factors, but in general, if the pulse oximeter shows 90% or above blood oxygen saturation the pilot’s brain should be receiving enough O2 to function normally. Below 90% mental function begins to deteriorate, and the pilot should use supplemental oxygen or descend to a lower altitude until oxygen saturation levels increase back to normal.Bottom line is: If you fly regularly above 10,000 feet msl, a pulse oximeter should be part of your equipment and you should check your oxygen saturation levels regularly during the fight. If you’d like to read more about hypoxia, below are links that go into greater detail.http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2016.pdf
Great weather for day 3 with large crowds. Busy day included two air shows—normal afternoon and evening. One ending with fireworks and the “wall of fire” which is a juvenile display of dynamite and gasoline blowing up for no other purpose than to blow something up for elementary school kids. If you are going to blow something up, let us try something that needs blowing up instead of wasting fuel and polluting the air.
Gave my regular “through the fence” forum. I hope this forum will become moot as this issue fads away as a bad memory. Because I was with the grandkids all day, I miss a tribute dinner for Bob Hoover. Fortunately, after I dropped the kids at the camp ground to sneak over to the Hilton for a drink with friends, I ended up sitting with Bob. For 93, his wit and quickness has not changed. He told a great story about the late Tex Hill, the famous fighter and test pilot, and him walking through the Hilton several years ago. He said Tex excused himself to go to the bathroom and said “I need to shake hands with the retired!”
I took several shots of Bob’s hands with my phone and one is posted. He is the greatest. Aircraft parking continues to be open and closed depending on the traffic flow. No significant incidents so far this year. EAA has a dedicated group of volunteers at the Chairman and Vice-Chairman levels who have a tremendous amount of experience & institutional knowledge. They donate a lot of time and should be thanked anytime you see them.
Day two opened with the 0730 safety briefing. I attend as one of the airshow “doc of the day” which could be dock on the bay, but whose interested in inadvertent rhyming—or I am just tired sleeping in a tent with 0730 meetings!
Attendance is up. The Osprey is pretty amazing. The crowd has actually cheered at the short field landing and takeoff competition and no mishaps except one wheels up landing in Appleton (no one hurt- pilot error).
My lecture on Special Issuance Medicals was well received with lots of questions. I hope it is my last lecture on the subject with what I think will be a great step forward—discontinuance of the 3rd medical in the near future.
Got to catch up with Mike Goulian and Patty Wagstaff—true airshow professionals. Patty is performing on Wednesday. Michael performed today and did his normal awesome job. Went to the Aircraft Parking party at Steve and Pat Owen’s house. It is always great to be able to thank these folks for their hard work and sometime thankless jobs. Remember, they are volunteers trying to accommodate a large number of folks. Give them a break and thank them profusely.
Also, went to the ICON party for a few minutes to catch up with the usual suspects. Party is always great but will be more exciting when they have a production aircraft. Rain and thunderstorm came in tonight. Pretty wet but no damage. Hope this pattern does not continue all week.
Attendance is up and parking is 99% full. Pilots are being redirected to Appleton and Fond du Lac! In spite of some clouds, the folks who were held up by the weather on Sunday have made it in. I presented Wayne Boggs, Air Boss, at the 11:30 AM air show safety briefing with a Rubber Chicken Emmy for Best Actor in the broad category “Aviation Theme Shows about Air Bosses” for his starring role in “Air Boss.” The air show performers enjoyed the event.
My lecture on concentration for the air show performers included the hint about sniffing rosemary but that is now an inside joke! Air show was very good, highlighted by Matt Chapman, Bill Stein and the US Marine Corp Osprey. One off airport landing was reported by the ultralight folks without injury or damage to the aircraft but the pilots did have to do the walk of shame as the aircraft was trailered back to the field.
The Thunderbird show line has been explained and many pilots are unhappy about not being able to go to their aircraft if they are parked in front of the T-Bird line from 1:30 PM to the Thunderbird show is finished, about 6 PM. Some are planning a departure on Friday to avoid the issue beginning Friday afternoon, however, advance sales for the weekend tickets are way up so EAA officials are happy.
Mosquitos were out Monday night as the wind died down and it warmed up a bit. More rain is predicted so the North 40 campers, including us, are preparing. The grandkids really enjoyed the show, and especially dinner, at the camp site which consisted of the hotdogs, baked beans and smores. What’s not to like?
Been through two exhibit halls (B & D) and the normal folks are still there. Lots of empty booths (I’d say 5% in D) and no Microsoft this year. Lots of kids trying to find simulators to try out but vendors are more interested in selling to pilots, as they are true training sims. EAA might want to consider a sim experience next year.
No medical issues have come up so far.
Camping was a proverbial water torture. No long rain storms, just one for fifteen minutes every couple of hours. Then it got cold so those who came to the North 40 without sleeping bags were a tad bit chilly. Drove around the grounds and the number of planes is down but this is probably due to the recurrent thunderstorms that kept us wet. I am sure more will come during the good weather today. At least density altitude will not be a problem.
Took the grandkids to Parnell’s for chicken and Andy’s for ice cream. Figured I would get the best off airport experiences for kids out of the way first! During our nightly sit around the airplane, we had a nice visit with Alex who is in the Air Force stationed in Alaska. He flew an American Champion down in a mere 35 hours. Convinced him he needed to stop by the Oregon Aero booth to pick up a seat pad for the trip back. His butt is pretty skinny and certainly is flat after that much butt time. He stopped at the Champion factory on the way to Oshkosh and was treated royally. Nice to see an engaged and excited young pilot willing to fly solo from Alaska to Wisconsin in a VFR aircraft.
Glad to report the North 40 showers are working as well as the bathrooms. Sure wish there was a way to keep the water running for shaving! Saw what appeared to be a funnel cloud over Lake Winnebago but turned out to be a “cold air funnel” according to the weather experts. Sure reminded us about the potential damage from severe weather on the EAA grounds.
Got the grandkids up early so we could get an early departure. Stopped by the bagel shop on the way to the airport to feed them. We were actually on time. Once we got to the hangar, we loaded the personal luggage (the only stuff left to load) and took off. Totally clear day out of Driggs, Idaho and as we traversed Jackson Hole, we climbed to 17,000 MSL to take advantage of the 40 knot tail wind.
Could probably have made it to Oshkosh nonstop but had there been any delays, we would have had a low fuel problem. One of the things about being an “older” pilot is not being so daring. We stopped in Staples, Minnesota which had two advantages—cheap fuel and by taking us north, we avoided a cluster of thunderstorms over South Dakota and Southern Minnesota.
We proceeded from Staples direct to Oshkosh avoiding a restricted area near Staples enjoying the same tailwind. Started out at 17K IFR but canceled near Ripon. We joined the line and it literally got so crowded that when we landed, the controls had planes in the pattern fly a race track down the runway and downwind to space all the traffic coming in from Fisk.
Once on the ground, we were rescued from a long line of singles going to the camping area by a parking marshal. Since twins have separate rows due to size and blast issues, this saved a lot of taxi time. Out of the plane at last and on the hallowed soil of KOSH, row 516, my almost regular row. Although we are camping, I do arrange for a rental car which helps with getting off the airport and hitting the grocery stores and other off campus events.
Setting up the tents with two kids is an interesting event. I thought we would have a fairly large “facility” until I saw the Taj Mahal a couple of planes down. We were slumming. After getting camp set up, we hit the Pic and Save for groceries. Brooks Hurst from Tarkio dropped by for beer with Air Boss Wayne Boggs. Brooks ended up stay in one of our tents since his hotel room was not ready till tomorrow. He was still functional after sleeping on the ground the next morning.
What is great about camping are all the folks in the campground. Meet folks from St. Louis, rural Georgia, New Jersey, and Kansas in just a short evening. Looking forward to more tomorrow.
-- Blog by Brent Blue MD
I have been planning for AirVenture Oshkosh for several months since I decided to go retro and actually camp in the North 40. I had written an article critical of the EAA Board not being connected to the membership and I thought they needed to be. I then announced that I would be camping since I felt I had missed some of the real spirit of AirVenture by staying in hotels and private homes. The EAA PR person said that they indeed have Directors who camped. Unfortunately, he was talking about camping in air conditioned motor homes which is somewhat akin to yachting.
I kept Amazon busy getting the necessary gear since I had long since given my non backpacking stuff away. I also decided to take my two grandchildren, Abbi and William, who are 13 and 10 respectively, so they could get the real feel Oshkosh. I had loaded most of the Rubber Chicken 340 about a week ago so we would be ready to hit the air early on Saturday and arrive in the early afternoon. Planned to stop in Staples, MN to take advantage of their cheap fuel ($4.88). I do not care how many times I have been to Oshkosh, I still get excited to get there. The last hour of the trip before landing is always the longest as I look forward to seeing friends made over the years and new friends to make this year.
Now that summer flying weather is coming around, long cross country trips might be in your horizon—even if it is on an airline. DVTs or deep venous thrombosis are one of the unfortunate risk factors for long air travel and should be taken seriously.
DVTs are promoted by sitting long periods of time, dehydration, injury to the legs (even small bruises), varicose veins, and inactivity. They can be prevented by keeping hydration up (and not drinking alcohol if on an airliner), doing isometric exercises in your airplane (or walking around the cabin on big iron), wearing support socks, and exercise before flights like walking or elliptical machines.
Although the jury is still out on aspirin, I think it is a good preventive medication and I personally take it for long trips.
When using your own aircraft for a long cross country, remember that that extra stop or two can make all the difference in DVT prevention. Walking around during refueling or even from the airplane to the restrooms will not only reduce your DVT risk but make everyone on board more comfortable.
The 2014 flying season is starting up with the opening of Sun ‘n Fun which means it is time to think about what makes our flying safer. Hypoxia (low oxygen levels) continues to be a problem for pilots even at altitudes below the 12,500 foot MSL FAA requirement. Many pilots, especially those with any underlying heart or pulmonary disease, who are obese, and even those who have had LASIK surgery, need oxygen below FAA mandated altitudes and there are simple ways to prove this to yourself.
My favorite example is to fly at night at 8,000 feet MSL or so for 30 minutes. Look at the lights around you. Then turn on some oxygen. Two liters per minutes should do. You will see the lights become brighter just like they were on a rheostat!
The same is true for our brains. After a long flight, even in a pressurized aircraft, our brains do not function as well be subjected to “relative hypoxia.” That is hypoxia that would not be clinically significant in a hospital setting but might make our thinking process or our reflexes not as good as they could be. Unfortunately, increased age tends to make this effect more pronounced.
Have you had LASIK surgery? Have you ever noticed that after a long flight, your vision does not seem to be quite 20/20? This is due to the hypoxic effect directly on the cornea. Unfortunately, this will not be improved with oxygen unless the mask covers your eyes as well.
Those big stomachs also get in the way of our breathing, especially when we are in a sitting position. Thus, hypoventilation or not taking a deep breath can increase our susceptibility to hypoxia at lower altitudes. Obviously, anyone with a history of heart or lung disease will have a lower tolerance to low ambient oxygen levels as well.
Oxygen is cheap and usually readily obtainable. Portable tanks can be filled at most gas or medical supply houses. (I will provide a free prescription if some yahoo requires it to fill a tank. Just email me at Aeromedix.com.) Unfortunately, only an A&P is supposed to fill a built in aircraft oxygen system but many choose to ignore this.
Also, oxygen is oxygen. It all comes from liquid sources now and there is absolutely no difference between medical oxygen and aviator’s oxygen. Without getting into a long explanation of why, just believe me on this. Oxygen is oxygen and it is all the same from an inhalation point of view so buy where ever you can find it.
The best way to know for sure what your oxygen level is by using a pulse oximeter. These inexpensive fingertip devices show the percentage of oxygen in your blood stream. The normal range for people who live at or near sea level is 95-100%. For people who live at 6,000’ MSL, it is 90 to 95%. My general recommendation for oxygen use is a person “should” use oxygen when their saturation drops by 5% from their home airport saturation and they “must” use oxygen if it drops by 10 percentage points.
When starting the oxygen, the pilot should titrate the flow of oxygen to raise their saturation back to their home airport baseline saturation. Remember that there is one thing that will “fool” a pulse oximeter and artificially raise your oxygen saturation reading—carbon monoxide. Carbon monoxide can leak into the cabin through cracks in the firewall, wheel wells, door seals, and even the tail cone. I recommend everyone carry a low level digital carbon monoxide detector.
Dr. Brent Blue is a Senior Aviation Medical Examiner based in Jackson Hole, Wyoming. He can be reached at email@example.com.
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