Pilot physiology – flying cross country

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?

While I love to read the posts on VAF about fly-outs and cross country adventures, this is a trip write-up with a different purpose. 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 most recent trip was nothing unique and there were not lots of inspirational pictures. So, I thought I’d make this trip write-up about safety – specifically about pilot physiology.

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. My hangar was at 40 degrees, and while I could sit on the ground waiting for the oil to warm, getting things up to 80 while in the hangar 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. The sliding canopy has a nasty draft and I wanted the cockpit to be comfortable. Pilot comfort is a safety task. You want to start the day at 100% and everything subtracts from that number – the fewer deductions, the better. [Fatigue]

I also started the pre-flight of the pilot. This included planning 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 there to be any risk of adding an extra stop just. 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 – a backup hand-held radio, camera, light weight gloves, hat, a water bottle, a pulse oximeter, and TravelJohn disposable bags. These last two are definitely safety items.

oximeter traveljohn

Any time I am flying above 8000′ I will pull out the pulse oximeter and periodically check. The FAA does not require oxygen below 12,500. That is not to say that the body is unaffected. 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. The problem is that drinking sufficient fluids results in two possibilities – you either drink too little or you need to eliminate liquid. My body much prefers being well hydrated. The TravelJohn disposable bags work as advertised. 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 that 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. I really don’t care how graphic this may seem. It’s a simple matter of this pilot’s physiology. [Stress, Fatigue]

As I mentioned, the first day was a log one and there were a limited number of daylight hours. I had several options planned out. First was my flight plan – 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. [Stress, Fatigue]

Winds are only accurate as they are occurring so there was no guarantee that the "plan" for one fuel stop would be possible. 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).

I watched both my fuel flow and my tank levels as I proceeded. The head wind was very close to forecast. I continually calibrate my fuel flow instrument with each trip and keep it about 5% pessimistic. As I approached my "one of two" fuel stop, I calculated my fuel remaining if I were to continue to my "one of one" stop. It was above my personal minimum (which in turn is above the FAA minimum). I wanted all of my available fuel in one tank (rather than have a small unknown amount in one tank). I used a stretch of sequential airports to run the tank down to zero and then another 20nm until my fuel flow indicated the tank was about to be empty. I then switched tanks. This confirmed both my calculations and that of the fuel computer. It also confirmed I had my personal minimums for fuel to make it to my "one of one" stop. Even still, I kept my flight plan over several alternate airports in case the winds changed. [Stress, Fatigue]

By the time I landed at Princeton Caldwell County airport, 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 never 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]

One Comment

  1. George says:

    When we did our 10 day tour around the NE in May, I thought I sure would have enjoyed one of those inflatable back cushions, if only because it offered options and change during the flight.

    Next time you get this close how about a heads up? I flew up to Greenville Downtown for lunch on Friday and would have enjoyed the chance for a meeting.