Stress: Not Just Wing Loads – Part One

Strike up a conversation at the FBO with a few pilots about stress and you’re likely to hear a detailed discussion on wing loading at the top of the “green arc,” maximum turbulent air penetration speeds, or maybe G-factor loads in steep turns. However, as I have talked about in previous articles, the central issue is that airplane parts are fixable and changeable; human parts are not. So when it comes to stress, the most important stress factors to manage are the personal stresses on each of us, not the wings of our airplanes.

Stress results from threatening interactions with almost anything in the internal or external environment that a person has that is perceived as straining or exceeding their ability to handle. Although people deal with and react to stress differently, everyone knows those gut-wrenching feelings of emotional strain and tension that result from many adverse and demanding circumstances.

There are some universally experienced psychological and physiological sensations associated with stressful situations. Some are so unpleasant that most people go well out of their way to avoid scenarios they know are likely to cause them. It’s helpful to understand the queasy subjective feelings of stress by knowing why we have these reactions.

Sensations of stress originate in one of evolution’s oldest parts of the brain known as the hypothalamus gland. The hypothalamus is a central part of the limbic system. The limbic system is made up of a number of nerve centers and is the home of the “emotional” system of the brain. This is also where the “fight or flight” reaction lives, those reflexes that were originally designed to keep our ancestors safe from woolly mammoths and saber-toothed tigers.

For such a tiny piece of brain, the hypothalamus is spectacularly important and essentially links the brain to the rest of the body. The hypothalamus does this by secreting chemicals it makes directly into the bloodstream, and that stimulates the endocrine system to pump “stress hormones” such as adrenaline, norepinephrine, and cortisol into the bloodstream. This ramps up every body system to fight or escape danger. When threatened, hypothalamic-mediated release and subsequent circulation of stress hormones affects pretty much every part of the body and leads to those unpleasant feelings we all experience as being all stressed out. The hypothalamus and its hormones control body temperature, thirst, emotions, blood pressure, heart rate, muscle tension, and secretion of digestive juices. So it’s easy to see why we feel stress sensations as our heart pounding, muscles trembling, dry mouth, “butterflies” in our stomach, and cold sweats. That “fight or flight” reaction was great for cave men, but for pilots these sensations are very distracting and interfere with the ability to make sound decisions in an emergency.

NASA and the NTSB have done some great research on the effects of these hormones on decision-making and have come up with some objective data. Their studies tell us what we already know, that when things get hairy, we feel that pounding in our chest and the yoke slips out of our sweaty palms. By measuring heart rate variability (HRV) and something NASA calls the “Task Load Index” (TLX), they can determine a pilot’s stress level and subjective workload in emergencies and implications on time-critical decision-making. They have found that the effects from the release of stress hormones are impaired access to stored knowledge, loss of concentration, loss of judgment, and an inability to choose the correct course of action.

This makes a lot of sense if you think about the last article where I talked about information storage centers in the brain and how this information is called up to make decisions. In an emergency, the release of stress hormones causes your brain to bypass these information sites, sending the decision-making process to the older parts of the brain designed to escape danger (“fight or flight”), not solve problems. This leads to abrupt actions that usually make the situation worse instead of better. Driven by the sudden release of these stress hormones, the first reaction is often the wrong thing to do. That’s why old pilot lore has sayings dealing with emergencies like “Wind the clock first” or “Never listen to your first reaction.”

The ability to make the correct decision under stress is among the most important safety skills a pilot develops. The key to this skill is to realize the impact of stress hormones on decisions and to overcome their effects and the tendencies that lead people under stress to react and not decide. Although the effects linger, if you can wait it out, stress hormones stay in the bloodstream for only a couple of minutes. Once their effects dissipate, the brain is freed up to use the higher cognitive centers where all that training and knowledge we have stored resides and allows for thought-based decisions rather than gut-level reactions. This is that “unfrozen” feeling you get a few minutes after the incident when “the fog clears” and you can think clearly again.

It is possible to speed the clearance of stress hormones so you can make quicker and more accurate decisions. Our mothers told us for years to “take a deep breath and just relax.” That’s easier said than done but actually has a sound basis in science. It turns out that stress hormones are rapidly metabolized and cleared from the bloodstream by the rich capillary networks of the lungs and liver. Taking a really deep breath increases venous blood return to the heart so each subsequent heart beat pumps more blood to these capillary areas, and that speeds up clearance of stress chemicals from the bloodstream and gives you back your cognitive capabilities. Another hormone-related factor is muscle tension; that “death grip” on the yoke CFIs always caution about. So while you take that first deep breath, force yourself to relax your muscles during the surge of stress hormones through your body; that also helps clear your head and leads to overall relaxation. Shrug your shoulders a few times, let them relax at your side, and make yourself loosen that tight grip on the yoke. While you’re at it, relax those clenched jaws, which will only ache later if you don’t.

The third technique for quick relaxation also comes from real science, and although it might sound a bit strange, bear with me on this because it also works very well. Neuroscientists measure brain electrical activity by placing electrodes on the head known as an EEG (electroencephalogram) to assess stress. Stress causes very fast chaotic electrical waves across the brain called alpha waves, and relaxation is characterized by slower regular rhythms known as beta waves. Using EEG studies, relaxation can actually be seen in real time as chaotic alpha (fight or flight) activity slows to more regular beta (cognitive) activity.

There is a way to convert those fast waves to slow waves that we can borrow from the psychologists’ techniques of relaxation hypnosis. This was already being done thousands of years ago and is the basis of ancient relaxation and meditation techniques. While you take a good deep breath, roll your eyes back and look up and as far back as you can. With real-time EEG monitoring this has been shown to quickly slow brain wave activity. You can practice this with friends (preferably good ones), family, and fellow pilots. When a partner watches you do this eye-rolling exercise, the farther back you can roll your eyes, the more of the white part of your eyes will show and the less of the pigmented iris they will be able to see. Psychologists use this simple test to see if a person would be easy to hypnotize for relaxation. This simple technique releases your brain from the grip of those overwhelming fight or flight chemicals, relieves acute stress, and returns your decision-making capacity.

We’re used to thinking of the three “R’s” from grade school as “reading, writing, and ’rithmetic.” There are three other “R’s” I teach my surgical residents in the operating room and pilots in the cockpit to deal with making correct decisions in emergency scenarios. First, Resist – resist the temptation to execute your first impulse to make a cave man response. Second, Relax – take a huge deep breath to use physiology in your favor and wash the acute stress chemicals from your blood stream. Relax your muscles and Roll your eyes back to induce slow beta wave electrical activity. Third, Reassess – refresh the decision-making process as the acute stress reaction clears and reassess options; use knowledge and training, not fight or flight reflexes, to solve the crisis. You’re likely to feel shaky and maybe have a headache from the stress hormone “hangover,” but you’ll be able to solve the problem and land safely back on the ground.

Now that we’ve covered the effects of acute stress, next month I’ll talk about the dangers of chronic stress on health and other methods to deal with it.

Kenneth Stahl, MD, FACS
Kenneth Stahl, MD, FACS is an expert in principles of aviation safety and has adapted those lessons to healthcare and industry for maximizing patient safety and minimizing human error. He also writes and teaches pilot and patient safety principles and error avoidance. He is triple board-certified in cardiac surgery, trauma surgery/surgical critical care and general surgery. Dr. Stahl holds an active ATP certification and a 25-year member of the AOPA with thousands of hours as pilot in command in multiple airframes. He serves on the AOPA Board of Aviation Medical Advisors and is a published author with numerous peer reviewed journal and medical textbook contributions. Dr. Stahl practices surgery and is active in writing and industry consulting. He can be reached at [email protected].
Topics: Pilot Health and Medical Certification, Pilot Health and Medical Certification

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