Stress

-Yogi Berra, Sports Illustrated (May 14, 1979)-

According to Transport Canada, stress is often a major contributing factor in aviation accidents. Stress is a difficult phenomenon to measure and quantify, except perhaps very indirectly through a measurement of the amount of adrenalin remaining in a post accident pilot’s bloodstream, so it is often overlooked in accident reports. We do know that nearly half of adults in North America suffer the adverse effects of stress and that stress related complaints account for over 75% of all visits to the doctor (1).

There is no doubt, however, that excess stress plays a significant role in the events preceding and leading up to aviation accidents and that developing a working knowledge of what stress is, how to recognize stress in ourselves, how it affects our performance and what we can do to control our stress levels can be of help in reducing the risks involved in flight.

Stress is actually a difficult concept to define in a precise way. Transport Canada uses the definition suggested by Miller and Smith, 1993: “Stress is the state of dynamic tension created when you respond to perceived demands and pressures from outside and from within yourself.”

The key words in the definition direct us toward the concepts of dynamic tension, response to perceived demands, and pressures from both outside and from within. Stress is, essentially, a form of resistance to perceived demands, both external and internal, and is self generated. Outside or inside events do not cause stress; they are simply the triggering mechanisms for our personal reactions.

All living beings experience some degree of stress, and a certain level of stress is, in fact, required to ensure a reasonable level of performance: the perceptions and responses required to deal effectively with our environment. An adequate level of dynamic tension between ourselves and our environment is necessary for successful interaction and response.

Each one of us operates at a different base level of stress which changes from day to day; hour to hour. Each one of us has a history: a genetic makeup, a set of memories, hopes, fears and expectations against which each new event or perception is measured and evaluated. Our response to each perceived demand, either internal or external, is the product of our measurement and evaluation against the background of our unique physical, mental and emotional makeup.

For one person, getting a credit card bill in the mail might be a non event or, perhaps, a minor irritation. For another person, the same bill might send their blood pressure through the roof, elicit a state of panic and leave them dysfunctional for the remainder of the day.

When flying, a stress level that is too low can be almost as dangerous as one that is too high. Our lowest level of stress occurs as we slide into sleep. A very low stress level can result in complacency, inattention and neglect of required duties. Too high a stress level,

particularly if that stress is prolonged, can result in exhaustion, serious errors in judgement and an inability to function, both physically and mentally. The Canadian Mental Health Association describes the “stress response”, the sequence of events we experience when faced with a stress producing situation, as a three step process: Stage 1, Mobilizing Energy; Stage 2, Consuming Energy Stores; and Stage 3,

Draining Energy Stores. In Stage 1 of the stress response process, the body perceives the stressor, the event or thought that triggers stress, and releases adrenaline. The heart and respiration rates increase. Our senses become more focused and sensitive; we become more perceptive and alert. Both good and potentially dangerous events can trigger this first stage.

At this stage our performance is excellent. We are alert, focused and yet still remain relatively relaxed and flexible. We are functioning, as we might say, at the top of our game. Depending on our overall fitness level at onset, this stage can last for a considerable time, but there are limits. Fatigue develops and our ability to maintain a high level of focus and function deteriorates. For most people, 2-3 hours is a reasonable limit to maintain a high level of focus and function in a demanding, vibrating, noisy environment like the cockpit of a small aircraft.

Some brave souls will tell you about their flights lasting 5-7 hours or even longer, but they are simply not functioning at the same level by the end of the flight as they were during the first few hours. This is one of the reasons that the descent, approach and landing phases of flight account for 61% of all accidents although they represent only 24% of the total exposure time during flight.

In Stage 2, the body begins to release stored sugars and fats to produce more available energy to meet the demands of an ongoing or more threatening stressful situation. The senses tend to become more narrowly focused and begin to exclude information that may not be evaluated as relevant to the immediate, perceived threat. We may also begin to experience an increased level of anxiety, memory loss and reduced ability to deal with more complex types of problems. Our ability to make sound judgements is becoming impaired.

Blood flow to the higher centres of the brain, the cerebral cortex, the portion of the brain responsible for processing complex mental activities such as thinking, remembering, perceiving, initiating voluntary movement, the mental home of decision making and judgement, is reduced. Our performance level begins to deteriorate. That old adage of being too scared to move has a solid, physiological basis. As the function of the cerebral cortex decreases, the limbic and cerebellum regions of the brain begin to take on a larger share of our total brain information processing functions. The limbic region, sometimes referred to as the mammalian brain, the “fight or flight” centre of the brain, whose major functions include control of emotions and the carrying out of routine, sequential activities begins to take more of a front seat in how we operate.

It is interesting to know that the three major regions of the brain, the cerebral cortex, the limbic region and the cerebellum, each have access to sensory input data and muscle response mechanisms. If you put your hand on a hot stove, the cerebellum, the region that controls such functions as balance, muscular coordination, heart rate, respiration rate and automatic responses, can respond much faster than the two, higher regions and without the need for conscious thought to force you to remove your hand from the perceived threat. It is not a region of the brain, however, capable of making reasoned judgements. The limbic region of the brain might be the first to respond to someone raising his hand in anger, posing a potential threat, without having to reference all those conflict

resolution courses you took on how to deal with angry people. That knowledge and those patterns of interaction will be resting comfortably in the cerebral cortex, put effectively on hold until the level of stress resulting from the situation is reduced. If Stage 2 continues for too long a period of time or the perceived threat is too powerful, we progress into Stage 3 of the stress response sequence. Our body’s need for energy now becomes greater that our ability to provide it. Our ability to respond in a meaningful way to our environment and our own thoughts deteriorates rapidly. Making sound judgements or solving complex problems becomes extremely difficult. We may still be able to perform uncomplicated, routine tasks but it will become impossible to respond effectively in an intelligent manner to unexpected or difficult situations.

Too much stress or too prolonged a period of stress renders each one of us dysfunctional and unsafe to pilot an aircraft. Stress, beyond a certain point, is not a performance enhancer. Recognizing our own, personal stress levels can be a complex problem particularly if we allow the stress response sequence to progress too far. If we fail to recognize and take positive steps to control an increasing stress level, we move toward stress levels where the judgements and the problem solving capabilities we need to make reasonable and intelligent decisions about how to handle a difficult situation degrade.

Each one of us will respond to stress in our own, unique manner and it is important to monitor and become familiar with our own patterns. Some typical symptoms of increasing stress that are easily observed are an increase in heart and respiration rates, increased muscle tension, rushed speech, a sense of impatience, increasingly mechanical responses, irritability and a tendency to focus on smaller aspects of a situation.

Gaining a familiarity with our own stress responses can be extremely helpful. If we can learn to recognize and take positive steps to reduce excess stress we will be more able to maintain a high level of function in a difficult environment. Deep breathing, taking a short break and focusing on standard procedures can all be extremely helpful in times of stress. There is an old tradition in the British Navy: regardless of the impending crisis, the captain always takes a moment to put on his hat before responding. He takes a moment for a breath and to collect his thoughts before engaging in the process of sorting out a difficult situation.

As with all human factors, successfully dealing with stress requires awareness, attitude, knowledge and discipline. We must be aware of our personal stress levels and their patterns, be familiar with our personal stress response symptoms and know the specific triggers that tend to increase or reduce our level of stress responses. Developing a proper attitude about stress and its importance, in terms of our actual capacity to deal effectively with the conditions we may encounter during a particular flight, is also very critical. The correct attitude toward safety directs us to respond in a positive manner to any signs of potential, developing problems. Knowledge is a very necessary part of the solution. We must know and understand what stress is, how it operates, both theoretically and personally, and what we can do to maximize its benefits and minimize its negative effects. Discipline provides the voice and practice to “do the right thing” each and every time. Without the required discipline to do the right thing each and every time we leave ourselves and our passengers vulnerable and unprotected from the potentially negative effects of stress.

A high stress level in the pilot is no less dangerous that a loss of oil pressure. Knowledge without discipline or awareness without the proper attitude does not carry the ball to the goal line. It is the combination of all four elements that allows us to minimize and manage risk.

Stress is something that affects each and every one of us. It can be either our best friend or our worst enemy, depending on our ability to recognize and effectively respond to our personal stress levels on an ongoing basis. Just as one might monitor temperature, oil pressure and fuel gauges during a flight, so too, pilot stress levels should be on the list of monitored elements contributing to a safe flight.

Notes:

1. Transport Canada, TP12863 (E), Human Factors for Aviation -- Basic Handbook, pg 107.