Skids Up No. 11: Human Factors


This is a slight detraction from the usual survival focus, but it is still part of the survival mindset.

Our aim through everything we do (pre-mission planning, briefings/debriefings, training and risk management) is to avoid the crash in the first place! ‘Dress to Egress’, underwater egress, and the four priorities of survival (protection, location, water and food) are for when we get it WRONG!

Remember back to the ‘Rule of 3s’? The first rule of 3s is ‘3 seconds following a bad decision’We need to be able to make clear, concise and informed decisions in the first place, or else we crash. Then you need to have read the previous ‘Skids Up’ blogs!

So, in this blog, we are going to look at two of the human factors that affect our decision-making process, and two that we can do something about. As far as stupidity, well, you know the answer to that one…

Let’s look at the last two elements taken from the ‘IM SAFE’ mnemonic:

  1. Illness
  2. Medication
  3. Stress
  4. Alcohol
  5. Fatigue
  6. Eating


‘Fatigue’ is broken into 2 parts:

  1. Fatigue through work overload.
  2. Fatigue through being tired.

Work overload is often overlooked. To save me writing a ton:

High work load = use a checklist = reduced cognitive overload = less fatigue

Simple as that! Lets move on to sleeping:

I love sleeping. However, I don’t agree with the ‘Anchor sleep’ concept of needing eight hours of sleep in every 24-hour period. Why? Simply because I was in the military. Any military the world over would laugh at the thought of eight hours of sleep in a night. For example, in Iraq, some infantry unit commanders would get one hour a night – for six months. UK Navy frigates operate during deployments on a six hours on, six hours off routine. But that’s 12 hours a day of sleep! In one of those six hours, you still have to do your normal ‘non- operational’ day-to-day job. During the other six, you must wait to be fed, shower, sleep, wake up, shower, eat, etc.; all whilst the ship is still moving and making noise. (It’s a 24 hours a day machine.)

How many of you readers have kids? You would also laugh at eight hours of sleep.

It’s how you and your body adapt. Yes, we try to get as much as we can when off duty or during duty time. I am not going into this aspect of sleep and fatigue too much, so I suggest you read the Guest blog by Jimmy McSparron ‘Effects of Fatigue in the Remote and Offshore Medic’.

One aspect I am a huge fan of is ‘strategic naps’. (I did say I love sleeping!)

Strategic Napping


As you may be aware, the multiple aircraft stressors that we encounter (e.g. concentration, motion noise and vibration) make operational flying tiring! As an example, we were involved in the humanitarian/emergency relief of a remote mine that was surrounded by ‘not very happy people’ and under a blockade. We flew three helicopters for over a month, carrying fuel and supplies as underslung cargo. We flew, on average, nine hours a day, every day for six days, with one day off for aircraft maintenance and crew rest. Then we repeated. As well as the aircraft stressors I mentioned above, we also had the addition of people shining mirrors at us (in attempts to blind us), as well as AK47 ground fire. This was all whilst maintaining a safe aircraft operation.

Fatigue was ever present as you might guess, so the operational strategy of taking a ‘NASA nap’ was used when and where we could. Extensive NASA research clearly demonstrates the effectiveness of brief naps. A six minute nap would improve performance by 34% and alertness by 54%. It’s all about how you fit it in, and how your managers, the public and everyone else perceive it.

Any stops for weather, food, waiting for the supply trucks to arrive/get into position, the helicopters were shut down and given to the maintainers to check. After calls of nature and coffee flask refills, a 20-minute break would be taken.

A word of warning though: With the advent of cell phones with camera, be aware of alleged ‘friends’ in the aircraft with you when the mission is complete…


A lot of research often baffles me, but this works far more effectively during prolonged operations than I would have ever believed. A planned and coordinated ‘NASA nap’ up to 45 minutes in duration is helpful, if operations permit. NASA has also proven that taking a ‘strategic nap’ during a night shift is incredibly difficult. Since the body naturally just wants to stay asleep, sleep inertia (or feeling ‘grogginess’) can last for up to an hour, if naps are taken during night-time.



We are all professionals and know of the effects of hypoglycemia. Altered mental status, your stomach rumbling when trying to talk to a patient, etc.

Not eating = bad decisions.

Whether you prefer three meals a day, snacking all day long, eating meat or being a vegan – Do whatever is normal for you. I personally don’t have a problem with any of those things. That’s why we are individuals and not robots. Unfortunately, what people do fail to do is adequately HYDRATE.

Carrying a water bottle is quite common nowadays, correct? From a post-crash survival standpoint, how many of you have a full water bottle on the return flight home? It’s usually all drunk by the time you reach your patient. But who wants to go flying with a full bladder? Who ACTUALLY wants to talk about ‘calls of nature’? Not many people, actually.

In a study by Omni Medical Systems, they found that ‘the practice of “tactical dehydration”, where pilots avoid the consumption of liquids for hours before missions in order to avoid in-flight bladder relief, is widespread in military aviation’. In “Review of Effects of Heat Stress and Potential Correlation on Mishaps in the CENTCOM Theatre of Operations”, they cite that the effects of an aircrew member having a full bladder. They state, “visual motor tracking, short-term memory, attention, and arithmetic efficiency were all impaired at 2% dehydration [while] 4% dehydration effects a 23% increase in response time (in comparison, a .08 Blood Alcohol Content level [legally “impaired” in all 50 states] yields a 17% increase in response time).” This argues that the operational risks of tactical dehydration may be greater than those of intoxication.


Peeing inside a helicopter is very complicated and doesn’t work for everyone for. obvious physical reasons. Commercially made “piddle packs” that convert urine into a gel for disposal are available, but this method involves partially undressing while sitting strapped in and flying in a helicopter. It’s as awkward as it sounds. The ‘piddle pack’ and ‘travel John’ failed the US Military Safe-to-Fly Flame Test, and they also found it cumbersome. Imagine a very small cockpit, seat/parachute harness, gloves, flight suit, anti-G suit – and then peeing whilst sat on an ejector seat. (If it ejects you by accident, it leaves you absolutely zero chance of survival). I missed that part on the movie Top Gun.

Needless to say, it was a massive problem.

For this very reason, studies undertaken by the US Air Force resulted in the development of the AMXDmax (Aircrew Mission Extender Device). It’s like a pair of boxer shorts with a cup/pad, urine detection sensor, pump and collection bag. You pee, it detects it and pumps it immediately into the bag. Hands-free pee!

To summarize, wee (pun intended) need to maintain our concentration in order to prevent a crash or error.

Eat, sleep and pee.

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  1. Aerosp Med Hum Perform.2015 Oct;86(10):875-80. doi: 10.3357/AMHP.4296.2015. Physical Fitness and Dehydration Influences on the Cardiac Autonomic Control of Fighter Pilots.


  1. Aerosp Med Hum Perform.2018 Feb 1;89(2):94-98. doi: 10.3357/AMHP.4920.2018. Aviator’s Fluid Balance During Military Flight.


  1. Mil Med.2019 Mar 1;184(3-4):e217-e222. doi: 10.1093/milmed/usy233. Effect of Urinary Sheath Use on Hydration Status of Fighter Pilots Under Severe Thermal Stress: An Observational Study.





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