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Old 12-15-2013, 04:45 PM
humptybump humptybump is offline
Join Date: Feb 2011
Location: USA
Posts: 3,181
Default Pilot physiology - evaluating a cross country trip

When it comes to pilot physiology If you do everything right, you start the day at 100%. Everything you do from that point on will be a deduction. The goal is to make the deductions as small as possible and as few as possible. What follows is how I completed a recent cross country flight with that goal in mind.

Let?s start with the handy mnemonic for pilot assessment ? IMSAFE
  • Illness ? Is the pilot suffering from any illness or symptom of an illness which might affect them in flight
  • Medication ? Is the pilot currently taking any drugs (prescription or over-the-counter)
  • Stress ? Psychological or emotional factors which might affect the pilot?s performance
  • Alcohol ? Although legal limits vary by jurisdiction (20 mg/mL blood in the UK,[2] one quarter that for driving), the pilot might want to consider their alcohol consumption within the last 8 to 24 hours
  • Fatigue ? Has the pilot had sufficient sleep and rest in the recent past
  • Eating ? Is the pilot sufficiently nourished?

Throughout what follows, I will label which of the above apply to my experience. In most cases, the label will refer to what I was attempted to minimize ? for example, all of the planning helped to reduce "stress".

My trip was to cover a couple thousand miles in three days. I knew I would have head winds on the first day and tail winds on the second and third days. My plan was for manage the winds as best as possible. [Stress]

A few days out I started to watch the weather. The headwinds would make the first day a long one and I had a limited number of daylight hours. [Stress]

I planned the longest day to be first and each subsequent day to be shorter. I knew I would not completely recharge each night being that I would be in a new place and would likely spend time catching up with people. [Stress, Fatigue]

The night before, I did my first pre-flight of the airplane and fueled up. This was a good plan since I noticed the tires were a little low from the current cold spell. I tested out a makeshift pre-heat solution.which would save me 10 minutes. [Stress, Fatigue]

During the evening pre-flight, I also took the opportunity to replace the piece of foam weather strip on the RV-8 canopy to eliminate draft - I wanted the cockpit to be comfortable. [Fatigue]

I also started the pre-flight of the pilot. This included a normal and definitely not late bedtime; skipping my usual glass of wine with dinner; and insuring the meal was something safe ? I did not want to be adding an unplanned stop. I also set out various snacks and liquids for the flight. [Alcohol, Fatigue, Eating]

In the morning, I loaded the airplane and then turned on the engine heater while I had breakfast and dropped the dog off for boarding. [Fatigue]

I completed a full preflight, pulled the plane out, closed the hangar, and finished the checklist for engine start and taxi. I used the last bit of time ? while the oil warmed up ? to load the full day?s flight plan into the GPS (it was already loaded into both my phone and tablet which would serve as my backup EFB). [Stress]

There are a few things I keep in the airplane at all times, among them are a pulse oximeter and TravelJohn disposable bags. These are definitely safety items.

Any time I am flying above 8000′ I will pull out the pulse oximeter and periodically check. Altitude flying is another of those things that makes a deduction from that 100%. For me, it is not large, but spending multiple hours at altitude does made a deduction. It?s easy enough to measure and the solution is to fly a lower altitude. Over the three days, I would not be above 9,500′ and each time I checked it was 95 or 96 (with a 92 in there to make me double check I had the finger sensor on correctly). [Illness, Fatigue]

I fully understand the affect of being under hydrated. My body prefers being well hydrated. The TravelJohn disposable bags work. Knowing I can pee whenever I need to means I never am "distracted" when it comes time for my approach to an airport, landing, and taxiing. I?d bet any pilot "in a hurry to get down" will make decisions differently than if they had no "pressure" to get to a bathroom. Just consider the decision of a troublesome landing ? whether it be a gust of wind, a poorly established approach, a little bounce on landing ? most of these are easily resolved with a go-around. But the "need to pee" is definitely weighing into the decision. [Stress, Fatigue]

I had several options planned out for my first day. I had two fuel stops for the 960nm flight ? one at KDVK and the other at KPOF. Each stop would add time on the ground. I preferred a single stop at 2M0. My solution was to flight plan both a single stop and two stops AND to identify multiple options for fuel between (the white markers in the map image). [Stress, Fatigue]

I watched both my fuel flow and my tank levels as I proceeded. The head wind was very close to forecast. I keep my fuel computer about 5% pessimistic. As I approached KDVK, I calculated my fuel remaining if I were to continue to 2M0. It was above my personal minimum (which in turn is above the FAA minimum). Even still, I kept my flight plan over several alternate airports in case the winds changed. [Stress, Fatigue]

By the time I landed at 2M0, I had been in the air for 4 hours and 45 minutes.

The only way that was possible was planning, backup plans, constant attention to the airplane, constant attention to the pilot, food, water, a TravelJohn, good clothing, and a comfortable cockpit. The landing was relaxed, unstressed, and uneventful ? even with some gusty winds and a bit of ice on the runway. [Fatigue]

With the longest leg done, the plane fueled, a pilot break, and a call to check in, I was back in the air after only 25 minutes on the ground. And for the record, that "call to check in" was another safety task. I had my lunch early into the second leg. [Fatigue, Eating]

The second leg of the day was easier ? it was shorter, the winds let up so my progress was quicker, I?d have plenty of daylight, and my destination was a bigger, and better maintained airport.

All day long, there were several people tracking my progress from my APRS tracker. While it is not designed as an emergency system, it does mean that individuals at both ends of my trip were aware of my location nearly every minute. This was helpful given my altitude was 2500′ for most of the trip and while flight following could maintain radio contact most of the time, there was not reliable radar contact. [Stress]

The rest of the trip was a lot less of the above. The legs were shorter times (even if one leg was 560nm) thanks to the tail winds. Each day was a single leg and only a few hours.

The one thing I deducted from that 100% was that my back was not thrilled by the RV-8 seat after that first long leg on day one. My tolerance did not come back to 100% for the rest of the trip. In the past, I?ve only once had a day of more than 4 hours. The RV-8 does not give you many options for moving around. This is one issue I will need to be experiment to find a solution. [Fatigue]
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Old 12-15-2013, 06:01 PM
rockwoodrv9 rockwoodrv9 is offline
Join Date: Dec 2011
Location: Meridian ID, Aspen CO, Okemos MI
Posts: 2,866

Nice report Glen. Good suggestions for people who do most of their flying around their local field. What an adventure heading out across the country and all that you learn along the way. The better prepared, the more fun you can have just looking around and seeing everything.
Williamston MI
O-320 D2A
Flying N376E
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Old 12-15-2013, 08:38 PM
dealfair dealfair is offline
Join Date: Feb 2006
Location: George West, TX
Posts: 567

Yes, good report & planning Glen. Have you tried Oregon Aero cushions?? The comfort they provide for a "bad back" is truly amazing.
Deal Fair
RV-4 (N34CB)
George West, TX (8T6)
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Old 12-16-2013, 06:29 PM
bret's Avatar
bret bret is offline
Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828

Nice write up, I use the oximeter all the time while flying where I am at. It is amazing what the lack of oxygen does to the mind. Without the meter you do not recognize what hypoxia. We often fly at 10500 to 12500, and use the meter often to see where we are at. The mind slows down and decisions are slower. That being said, we do not currently have O2, but that is on our priority purchase list.
7A Slider, EFII Angle 360, CS, SJ.
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Old 12-16-2013, 07:13 PM
humptybump humptybump is offline
Join Date: Feb 2011
Location: USA
Posts: 3,181

My RV-8 is all set for O2. My problem is sourcing refills of my bottles.
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Old 12-16-2013, 07:52 PM
CharlieMike CharlieMike is offline
Join Date: Apr 2013
Location: --
Posts: 9

Speaking of O2 levels, has anyone ever used an oximeter when on top of Pikes Peak or similar high mountain top? Just curious at 14,000' plus feet when exerting yourself by walking and climbing around how low oxygen levels drop down to. I do carry an oximeter in my plane, which I picked up at my local aviation department at WalMart.

Now I'm not advocating not using oxygen at high altitudes, just an inquiring mind.
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Old 12-16-2013, 08:01 PM
humptybump humptybump is offline
Join Date: Feb 2011
Location: USA
Posts: 3,181

I'd actually guess pilots are not doing our selves a service - just sitting still and breathing shallow at altitude. I did a few deep long breaths on my recent trip and it did lift my O2 level.

I can't speak to Pikes Peak and I did not have a pulse oximeater when I was on Kinabalu but I can tell you it was much tougher to hike an incline at the peak than it was at the base and sleeping above 11,000' is not fun unless you've acclimated. ... and I was in great shape back then (not so much now).

Last edited by humptybump : 12-16-2013 at 08:05 PM.
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Old 12-16-2013, 09:44 PM
Gisnar Gisnar is offline
Join Date: Nov 2012
Location: Northern Nevada
Posts: 140

At White mountain peak in California, 14252 ft, and at Mount Whitney, 14505 ft I run oxygen saturations of 85-89%.
At my home at 5000 ft I run about 96%, I am only slightly higher at sea level probably because of physiologic shunt.
None of those are dangerous, just FYI
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Old 12-16-2013, 09:47 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,075

No, those lower values won't hurt you in the short term, unless you crash because of the lack of mental acuity they involve.

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Old 12-16-2013, 09:51 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,075

Getting back to the OP, one thing I do when I leave home to go to the airport, even for a local flight, is start monitoring myself. I figure that if I make three screw-ups while I'm still on the ground, I'd better stay there.

These are things like forgetting to bring something pertinent to the flight or similar goofs. My thought is that if I can't even do the basics well enough, I'm not safe that day.

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