**3.2 Psychological Stress:**

Definition of psychological stress

Sources of psychological stress

Assessment of psychological stress

Symptoms, signs, and performance effects of psychological stress

Countermeasures

(draft by David R. Jones, MD, MPH, 3 June 2002)

Ref:

Helmreich R, Gregovich S, Wilhelm J, et al. [Personality based clusters
as predictors of aviator attitudes and performances]{.underline}. In:
Jensen R, ed. *Proceedings of the Fifth Symposium on Aviation
Psychology.* Columbus; Ohio State University Press, 1989; 607-702.

Jones DR. Flying and danger, joy and fear. Aviat Space Environ Med 1986;
57:161-6.

The demands of aviation upon pilots cause Aviation Medical Examiners
(AMEs) and other aeromedical practitioners to be concerned with
manifestations of mental disorders at subclinical levels that are of
little practical concern to most other physicians. The same is true of
stress: sub-acute levels of negligible importance in most fields of
human endeavor may affect pilots in ways that seriously degrade aviation
effectiveness and safety.

Hans Selye was one of the first physicians to associate stress with
disease in an organized way. He defined *stress* as the nonspecific
response of the organism to any demand placed upon it (Selye, 1957).
Alan Roscoe (1978) noted that the word *stress*, when associated with
flying, tended to imply danger. He divided stressors into short- and
long-term categories, and went on to comment upon the difficulties of
simulating aviation stressors under laboratory conditions. These
difficulties continue today.

For example, consider a simple question, "Is *psychological stress* a
distinct entity?" Its definition is difficult to articulate clearly and
briefly, since giving whatever-it-is a name requires us to identify
factors that distinguish *psychological* stress from other types of
stress. We have no universal measure for "stress." Psychological stress
cannot be defined solely as an influence originating outside the
individual, as in, "An angry spouse causes psychological stress," since
a specific event or situation may distress one person and not another,
or may distress a given person more on one day than on another. To use
physical analogies for these two arguments, falling out of a tree may
affect different people in different ways, and one may step off the same
curb for years and then one day step off and sprain an ankle.

Further, just as there is no single cause for all broken legs, a
particular stress-related syndrome may result from many sorts of
stressors, both acute and chronic. No laboratory experiment can
duplicate all these stressors, or their many combinations in real life.
For example, an experiment concerned with acute cockpit task saturation
cannot include the influences of concomitant worries about a spouse's
therapy for malignancy.

Discussions of psychological stress in aviation may involve somewhat
circular reasoning, categorizing the effects in terms of the stressor
(i.e., accidents due to get-home-itis), and defining the stressor in
terms of its actual or possible effects (pilots in a hurry to get home
\[self-imposed stress\] may make several sorts of mistakes). As with the
Supreme Court and pornography, we are left with the feeling that, while
we can't clearly define psychological stress, we know it when we see it.
More practically, we may decide that precisely defining and measuring
psychological stress in the arena of aviation is less important than
assessing its consequences (Stokes & Kite, 1994, p. 50ff).

Stokes & Kite (1994) extensively reviewed the subjects of stress,
fatigue and performance in aviation. They point out a pervasive error in
many considerations of this subject; namely, citations of the
Yerkes-Dodson inverted-U curve (1908), often presented uncritically as
definitive evidence that an optimum amount of stress (or arousal) is
necessary for excellent performance, and that performance declines
equally if the subject (or pilot) is under too much or too little stress
(or arousal).

Stokes and Kite offer several explicit criticisms of this use of the
Yerkes-Dobson curve. First, the original work was done with mice, not
pilots. The stimulus was one rarely found in the cockpit---a series of
graduated electric shocks. The desired performance, only slightly less
remote from aircrew duties, was for the mice to choose a light-colored
or a dark pathway. Second, the classical distribution curve that
frequently accompanies discussions of the original work bears little
relation to the authors' own graphs of their data. In fact, Stokes &
Kite reflect at some length upon the similarities of the Yerkes-Dodson
"curve" to the Bermuda Triangle in terms of its flexibility of geometry
and its application to various poorly defined situations (1994, p. 43).
Third, the research was not particularly well done or reported, and
subsequent investigators have not been able to replicate its claimed
results. Finally, the concept is counterintuitive and lacks face
validity. "Certainly pilots and controllers don't go around saying,
'I've had a bad week; wasn't stressed enough.'...As far as we know, not
a single author \[having cited the inverted-U paradigm\] goes on to
recommend...*moderately* strained employee-management relations for air
traffic controllers, *mildly* upsetting preflight arguments for aircrew
or, perhaps, *somewhat* bothersome aircraft unreliability. The fact
that, in this context, it is impossible to cite some quite probable
'real world' stressors without sounding tongue-in-cheek should alert us
to the fact that something is not right" (Stokes & Kite, p. 34, emphases
in the original).

Stokes and Kite emphasize the importance of distinguishing clearly
between *stress* and *arousal* in discussions of aviation performance.
Stress cannot be the sole cause or the inevitable result of arousal;
some arousal is, in fact, pleasant and much sought after. Rather,
"various cognitive, biochemical and psychophysiological functions are
likely to be influenced differentially depending upon the eliciting
conditions. These changes, however, need not necessarily be associated
with *any* general alteration in performance" (1994; p. 45, emphasis in
the original). They go on to assert that cognitive performance contains
many elements, and the nature of a "stress related change" will depend
upon the nature of the task (e.g., flying or air traffic control).

A further variable is the personality of the person involved. One pilot
may be uncomfortable with approximations and 'guesstimates,' and use a
personal talent for mental mathematical computations to maintain exact
control over instrument flight operations. Another pilot, having
stronger scanning and visual-spatial skills, may use these skills by
applying various 'rules of thumb' to accomplish instrument flight
through "approximation plus progressive fine tuning," thus avoiding the
precise mental calculations that he regards as bothersome. Either pilot
may feel hampered and "stressed" by being forced into the other's mode
(example adapted from Stokes & Kite, 1994, p. 47).

The aviation medicine literature reflects two major themes in
stress-related studies on pilot effectiveness and safety, themes
reflected in the study of pilots who develop fear of flying (Jones,
1986). The first theme concerns the effects upon flight performance of
stressors unique to aviation activities (i.e., weather, hypoxia, rapid
barometric changes, g-forces, circadian dysrhythmia, the intrinsic
dangers of flight, air combat). The second theme concerns the effects
upon flight performance of everyday stressors common to all humanity
(maladaptive personality traits, relationship problems, marital
stresses, family conflicts, financial setbacks). (For a thoughtful
discussion of such factors as they apply to long-duration space flight,
see Kanas, et al., 2002). Anyone who has read aviation accident reports
recognizes that either set of stressors can cause accidents: a pilot can
die from bad decisions made under the stress of an inflight fire, or
from a bad decision to press on in deteriorating weather so as not to
miss his daughter's graduation.

Psychological stressors, whether imposed from without or generated from
within the flier, may influence pilot effectiveness and safety in ways
involving overt, conscious and unconscious influences upon
aviation-related perceptions, interpretations, decisions and actions.
Fliers may manifest stress through physical and physiological channels
(heart rate, blood pressure, blanching or flushing, sweating, intestinal
motility, desire to urinate, trembling, muscular tension, headache).
Stress may affect mental functions (attention, cognition, memory,
judgment, recognition and interpretation of sensory inputs). It may
express itself through emotional channels (personal feelings of shame,
guilt, anger, depression, fear, anxiety). Stress may alter behavior
(motor performance, speed, accuracy, reversion to previously learned
patterns, freezing up, panic); and through many combinations of signs
and symptoms. Because "stress" involves varied effects of various
causes, we have no single indicator, no "gold standard," with which to
calibrate the effect of stress upon a flier or group of fliers (a
fighter squadron, for example). This lack of precision extends to our
inability to simplify matters of "morale" or "fatigue," or other human
factors that are so salient in aviation safety and effectiveness.

The goal of the aviation community, and thus of AMEs, is to remove or
reduce psychological stress as a detractor from aviation effectiveness
and a cause of aviation accidents. In order to do so, we may invoke the
five classic levels of preventive medicine: general prevention,
individual protection, early diagnosis, effective therapy and rapid
rehabilitation. We aim to keep the stressors upon the general population
of fliers as low as possible, to protect the individual fliers from
aviation and life stressors, to detect stress effects through early
recognition by self or others, to reduce or treat stress-related
symptoms effectively, and to return those grounded for such conditions
as quickly as possible.

The first level of defense is to reduce identifiable stressors in the
world of aviation. Many "human factors" elements derive from this
approach---simplified instrumentation, clear procedures, redundant
systems. Making aviation as simple and predictable as possible reduces
its stressfulness. Cockpit (or Crew) Resource Management (CRM), an
approach promulgated by Helmreich and associates, embodies an excellent
approach both to prevention and, in the total crew environment, to
"treatment" of the effects of stress, although CRM does not present
itself specifically as therapeutic (Helmreich et al., 1989). AMEs can
contribute to lowering the influence of stressors on aircrew by
discussing the effects that emotions can have on flying performance with
individual fliers, or with groups of fliers. Such opportunities may be
formal or informal, planned or spontaneous. Be aware of them, and take
advantage of them. Most fliers will have heard some or all of the
material before, but it never hurts to reinforce such hard-learned
lessons, and something may be learned that will prevent an accident.
Using a group approach to such discussions carries the added advantage
of not focusing upon one pilot, an act that the pilot might find
embarrassing or accusatory. The approach of recurrent briefings on
familiar topics is exactly the same as the one that fliers use in
rehearsing emergency procedures, or reviewing well-known principles of
flying in bad weather.

The second level of defense is to reduce individual stress levels.
Separate the stressors in time (don't start to sell the house until
after the daughter's wedding). If possible, wait for temporary stressful
situations to pass, or settle them. (An adage has it that pilots
involved in situational reactions prefer to change the situations rather
than to change their reactions.) A pilot may be aware of a stressor (for
example, a serious financial decision), but unaware that its effects are
so deep-rooted as to be causing him to be uneasy about or even fearful
of flying (Jones, 1986).

If changing the situation is not possible, the third level of
defense---early detection---is to learn countermeasures. This begins
with someone, either the pilot or another person, recognizing that the
pilot is showing early signs of undue stress. A flier may evaluate him
or herself before every flight for psychological fitness to fly: not
hurried, worried, preoccupied, jittery, irritable, autonomically aroused
or upset (see above). A pilot who knows he or she is showing signs of
distress may apply learned relaxation techniques as a counter: deep
muscle relaxation, mind-clearing exercises, breathing techniques. Or
perhaps this is a not a day to fly.

A private pilot may decide not to fly, or have another pilot help with
the flight or just come along as a precaution. A commercial pilot may
frankly discuss his or her situation that day with crewmembers so that
they will be aware and watchful for mistakes, or may decide to call in
sick or take a few days of leave. If such a simple step is not possible
(and, of course, we will never know how many accidents did not happen
because a wise pilot decided not to take that flight today), then teach
pilots how to deal with whatever they identify as psychological
stressful.

If a pilot does not recognize or acknowledge personal stress indicators,
the group with which the pilot is associated may learn about such
indicators and assume a social responsibility for discussing them.
Military commanders and squadron associates of today feel much more at
ease with such procedures than their predecessors of a few decades back,
when the stiff upper lip was the norm. Commercial aircrews learn CRM
techniques and practice them in simulators under professional
supervision. Airlines and other aviation companies provide Employee
Assistance Programs and encourage frank, non-authoritarian
communications within the cockpit. The aviation community as a whole has
become more open and accepting of stress reduction programs and
awareness as a vital component of a wider human factors approach to
aviation safety. Such stress indicators as alcohol abuse, behavioral
changes, loss of sense of humor, change in attitude toward work,
irritability, bad temper, sulking, social withdrawal, or maladaptive
attitudes should be noticed and pointed out to the individual or, if
necessary, his or her supervisor and possibly to aeromedical personnel.

In terms of more formal treatment and of rehabilitation (return to
effective and safe flying), the flier may seek outside help. An
emotionally distressed flier may present to a flight surgeon or AME with
physical symptoms rather than emotional complaints. For example, a
depressed flier may be aware of the somatic symptoms (change in
appetite, change in bowel habits, change in sleep pattern, fatigue or
loss of energy, loss of usual ability to concentrate or remember,
headaches and other minor but annoying aches or pains). The same flier
may not be aware of the emotional components of depression (apathy, loss
of joy in life, psychomotor slowing or agitation, depressed mood,
feelings of worthlessness or undeserved guilt, self-reproach, or even a
desire to die). Thus, AMEs must maintain a clinical sensitivity to the
possibility of stress-related factors in all clinical interactions with
their fliers. If a formal diagnosis is present, removal from flying is a
possibility. This should be presented in terms of not flying until the
situation or the reaction is settled, so that the flier may then return
to safe and effective flight. The use of most medications in such
situations precludes flying, and such use may imply a psychopathology
that is beyond the scope of this Instruction. If counseling or
psychotherapy is indicated, the flier may return to flying duties once
the symptoms are better, even though the therapy is continuing. Such
instances probably will involve decisions by FAA aeromedical
authorities.

REFERENCES

Helmreich R, Gregovich S, Wilhelm J, et al. [Personality based clusters
as predictors of aviator attitudes and performances]{.underline}. In:
Jensen R, ed. *Proceedings of the Fifth Symposium on Aviation
Psychology.* Columbus; Ohio State University Press, 1989; 607-702.

Jones DR. Flying and danger, joy and fear. Aviat Space Environ Med 1986;
57: 131-6.

Jones DR. [Psychiatric factors in civil aviation medicine]{.underline}.
AME Seminar Handout. 2001. Oklahoma City: Civil Aviation Medical
Institute.

Kanas N, Salnitsky V, Grund EM et al. Lessons learned from Shuttle/Mir:
psychosocial countermeasures. Aviat Space Environ Med 2002; 73: 607-11.

Roscoe AH. Stress and workload in pilots. Aviat Space Environ Med
197778; 49:630-6.

Selye H. Stress of life. 1957. London: Longmans Green. Cited in Roscoe
AH, *op cit.*

Stokes A, Kite K. Flight Stress: stress, fatigue, and performance in
aviation. Brookfield, VT: Ashgate Publishing Co., 1994.

Yerkes RM, Dodson JD. The relation of strength of stimulus to rapidity
of habit-formation. Journ Comp Neurol Psychol 1908; 18: 459-82. Cited in
Stokes & Kite, *op. cit.*, p. 34ff.

Ref:

1\. Jones DR. [Psychiatric factors in civil aviation
medicine]{.underline}. AME Seminar Handout. 2001. Oklahoma City: Civil
Aviation Medical Institute.

2\. Stokes A, Kite K. Flight Stress: stress, fatigue, and performance in
aviation. Brookfield, VT: Ashgate Publishing Co., 1994.