Remote Pilot – Small Unmanned Aircraft Systems Study Guide 45
Chapter 9:
Physiological Factors (Including Drugs and Alcohol) Affecting Pilot
Performance
Introduction
14 CFR part 107 does not allow operation of small UA if the remote PIC, the person manipulating the
controls, or Visual Observer (VO) is unable to safely carry out his or her responsibilities. It is the remote
PIC’s responsibility to ensure all crewmembers are not participating in the operation while impaired.
While drug and alcohol use are known to impair judgment, certain over-the-counter (OTC) medications
and medical conditions could also affect the ability to safely operate a small UA. For example, certain
antihistamines and decongestants may cause drowsiness. We also emphasize that part 107 prohibits a
person from serving as a remote PIC, person manipulating the controls, VO, or other crewmember if he
or she:
• Has consumed any alcoholic beverage within the preceding 8 hours
• Is under the influence of alcohol
• Has a blood alcohol concentration of .04 percent or greater
• Is using a drug that affects the person’s mental or physical capabilities.
There are certain medical conditions, such as epilepsy, may also create a risk to operations. It is the
remote PIC’s responsibility to determine that their medical condition is under control and they can
safely conduct a small UA operation.
Physiological/Medical Factors that Affect Pilot Performance
Important medical factors that a pilot should be aware of include the following:
• hyperventilation
• stress
• fatigue
• dehydration
• heatstroke
• the effects of alcohol and drugs
Hyperventilation
Hyperventilation is the excessive rate and depth of respiration leading to abnormal loss of carbon
dioxide from the blood. This condition occurs more often among pilots than is generally recognized.
It seldom incapacitates completely, but it causes disturbing symptoms that can alarm the
uninformed pilot. In such cases, increased breathing rate and anxiety further aggravate the
problem. Hyperventilation can lead to unconsciousness due to the respiratory system’s overriding
mechanism to regain control of breathing. Pilots encountering an unexpected stressful situation
may subconsciously increase their breathing rate.
Common symptoms of hyperventilation include:
• Visual impairment
• Unconsciousness
• Lightheaded or dizzy sensation
• Tingling sensations
Chapter 9: Physiological Factors (Including Drugs and Alcohol) Affecting Pilot Performance
Remote Pilot – Small Unmanned Aircraft Systems Study Guide 46
• Hot and cold sensations
• Muscle spasms
The treatment for hyperventilation involves restoring the proper carbon dioxide level in the body.
Breathing normally is both the best prevention and the best cure for hyperventilation. In addition to
slowing the breathing rate, breathing into a paper bag or talking aloud helps to overcome
hyperventilation. Recovery is usually rapid once the breathing rate is returned to normal.
Stress
Stress is the body’s response to physical and psychological demands placed upon it. The body’s
reaction to stress includes releasing chemical hormones (such as adrenaline) into the blood and
increasing metabolism to provide more energy to the muscles. Blood sugar, heart rate, respiration,
blood pressure, and perspiration all increase. The term “stressor” is used to describe an element
that causes an individual to experience stress. Examples of stressors include physical stress (noise or
vibration), physiological stress (fatigue), and psychological stress (difficult work or personal
situations).
Stress falls into two broad categories: acute (short term) and chronic (long term). Acute stress
involves an immediate threat that is perceived as danger. This is the type of stress that triggers a
“fight or flight” response in an individual, whether the threat is real or imagined. Normally, a healthy
person can cope with acute stress and prevent stress overload. However, ongoing acute stress can
develop into chronic stress.
Chronic stress can be defined as a level of stress that presents an intolerable burden, exceeds the
ability of an individual to cope, and causes individual performance to fall sharply. Unrelenting
psychological pressures, such as loneliness, financial worries, and relationship or work problems can
produce a cumulative level of stress that exceeds a person’s ability to cope with the situation. When
stress reaches these levels, performance falls off rapidly. Pilots experiencing this level of stress are
not safe and should not exercise their airman privileges. Pilots who suspect they are suffering from
chronic stress should consult a physician.
Fatigue
Fatigue is frequently associated with pilot error. Some of the effects of fatigue include degradation
of attention and concentration, impaired coordination, and decreased ability to communicate.
These factors seriously influence the ability to make effective decisions. Physical fatigue results from
sleep loss, exercise, or physical work. Factors such as stress and prolonged performance of cognitive
work result in mental fatigue.
Like stress, fatigue falls into two broad categories: acute and chronic. Acute fatigue is short term and
is a normal occurrence in everyday living. It is the kind of tiredness people feel after a period of
strenuous effort, excitement, or lack of sleep. Rest after exertion and 8 hours of sound sleep
ordinarily cures this condition.
A special type of acute fatigue is skill fatigue. This type of fatigue has two main effects on
performance:
• Timing disruption—appearing to perform a task as usual, but the timing of each component is
slightly off. This makes the pattern of the operation less smooth because the pilot performs
each component as though it were separate, instead of part of an integrated activity.
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Remote Pilot – Small Unmanned Aircraft Systems Study Guide 47
• Disruption of the perceptual field—concentrating attention upon movements or objects in
the center of vision and neglecting those in the periphery. This is accompanied by loss of
accuracy and smoothness in control movements.
Acute fatigue has many causes, but the following are among the most important for the pilot:
• Mild hypoxia (oxygen deficiency)
• Physical stress
• Psychological stress
• Depletion of physical energy resulting from psychological stress
• Sustained psychological stress
Acute fatigue can be prevented by proper diet and adequate rest and sleep. A well-balanced diet
prevents the body from needing to consume its own tissues as an energy source. Adequate rest
maintains the body’s store of vital energy.
Chronic fatigue, extending over a long period of time, usually has psychological roots, although an
underlying disease is sometimes responsible. Continuous high-stress levels produce chronic fatigue.
Chronic fatigue is not relieved by proper diet and adequate rest and sleep and usually requires
treatment by a physician. An individual may experience this condition in the form of weakness,
tiredness, palpitations of the heart, breathlessness, headaches, or irritability. Sometimes chronic
fatigue even creates stomach or intestinal problems and generalized aches and pains throughout
the body. When the condition becomes serious enough, it leads to emotional illness.
If suffering from acute fatigue, a remote pilot should not operate a small UA. If fatigue occurs during
the operation of a small UA, no amount of training or experience can overcome the detrimental
effects. Getting adequate rest is the only way to prevent fatigue from occurring. Avoid flying a small
UA without a full night’s rest, after working excessive hours, or after an especially exhausting or
stressful day. Remote pilots who suspect they are suffering from chronic fatigue should consult a
physician.
Dehydration
Dehydration is the term given to a critical loss of water from the body. Causes of dehydration are
hot temperatures, wind, humidity, and diuretic drinks—coffee, tea, alcohol, and caffeinated soft
drinks. Some common signs of dehydration are headache, fatigue, cramps, sleepiness, and dizziness.
The first noticeable effect of dehydration is fatigue, which in turn makes top physical and mental
performance difficult, if not impossible. Flying a small UA for long periods in hot summer
temperatures or at high altitudes increases the susceptibility to dehydration because these
conditions tend to increase the rate of water loss from the body.
To help prevent dehydration, drink two to four quarts of water every 24 hours. Since each person is
physiologically different, this is only a guide. Most people are aware of the eight-glasses-a-day
guide: If each glass of water is eight ounces, this equates to 64 ounces, which is two quarts. If this
fluid is not replaced, fatigue progresses to dizziness, weakness, nausea, tingling of hands and feet,
abdominal cramps, and extreme thirst.
The key for pilots is to be continually aware of their condition. Most people become thirsty with a
1.5 quart deficit or a loss of 2 percent of total body weight. This level of dehydration triggers the
“thirst mechanism.” The problem is that the thirst mechanism arrives too late and is turned off too
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Remote Pilot – Small Unmanned Aircraft Systems Study Guide 48
easily. A small amount of fluid in the mouth turns this mechanism off and the replacement of
needed body fluid is delayed.
Other steps to prevent dehydration include:
• Carrying a container in order to measure daily water intake.
• Staying ahead—not relying on the thirst sensation as an alarm. If plain water is not preferred,
add some sport drink flavoring to make it more acceptable.
• Limiting daily intake of caffeine and alcohol (both are diuretics and stimulate increased
production of urine).
Heatstroke
Heatstroke is a condition caused by any inability of the body to control its temperature. Onset of
this condition may be recognized by the symptoms of dehydration, but also has been known to be
recognized only upon complete collapse.
To prevent these symptoms, it is recommended that an ample supply of water be carried and used
at frequent intervals, whether thirsty or not. The body normally absorbs water at a rate of 1.2 to 1.5
quarts per hour. Individuals should drink one quart per hour for severe heat stress conditions or one
pint per hour for moderate stress conditions. For more information on water consumption, refer to
the “Dehydration” section of this chapter.
Drugs
The Federal Aviation Regulations include no specific references to medication usage. Title 14 of the
CFR prohibits acting as PIC or in any other capacity as a required pilot flight crewmember, while that
person:
1. Knows or has reason to know of any medical condition that would make the person unable to
meet the requirement for the medical certificate necessary for the pilot operation, or
2. Is taking medication or receiving other treatment for a medical condition that results in the
person being unable to meet the requirements for the medical certificate necessary for the
pilot operation.
Further, 14 CFR part 107 and 14 CFR part 91, sections 91.17 and 91.19 prohibit the use of any drug
that affects the person’s faculties in any way contrary to safety.
There are several thousand medications currently approved by the U.S. Food and Drug
Administration (FDA), not including OTC drugs. Virtually all medications have the potential for
adverse side effects in some people. Additionally, herbal and dietary supplements, sport and energy
boosters, and some other “natural” products are derived from substances often found in
medications that could also have adverse side effects. While some individuals experience no side
effects with a particular drug or product, others may be noticeably affected. The FAA regularly
reviews FDA and other data to assure that medications found acceptable for aviation duties do not
pose an adverse safety risk.
Some of the most commonly used OTC drugs, antihistamines and decongestants, have the potential
to cause noticeable adverse side effects, including drowsiness and cognitive deficits. The symptoms
associated with common upper respiratory infections, including the common cold, often suppress a
pilot’s desire to fly, and treating symptoms with a drug that causes adverse side effects only
compounds the problem. Particularly, medications containing diphenhydramine (e.g., Benadryl) are
Chapter 9: Physiological Factors (Including Drugs and Alcohol) Affecting Pilot Performance
Remote Pilot – Small Unmanned Aircraft Systems Study Guide 49
known to cause drowsiness and have a prolonged half-life, meaning the drugs stay in one’s system
for an extended time, which lengthens the time that side effects are present.
Prior to each and every flight, all pilots must do a proper physical self -assessment to ensure safety.
A great mnemonic is IMSAFE, which stands for Illness, Medication, Stress, Alcohol, Fatigue, and
Emotion.
For the medication c omponent of IMSAFE, pilots need to ask themselves, “Am I taking any
medicines that might affect my judgment or make me drowsy? For any new medication, OTC or
prescribed, you should wait at least 48 hours after the first dose before flying to determine you do
not have any adverse side effects that would make it unsafe to operate an aircraft. In addition to
medication questions, pilots should also consider the following:
• Do not take any unnecessary or elective medications.
• Make sure you eat regular balanced meals.
• Bring a snack.
• Maintain good hydration - bring plenty of water.
• Ensure adequate sleep the night prior to the flight.
• Stay physically fit.
Alcohol
Alcohol impairs the efficiency of the human body.
[Figure 9-1] Studies have shown that consuming
alcohol is closely linked to performance deterioration.
Pilots must make hundreds of decisions, some of them
time-critical, during the course of a flight. The safe
outcome of any flight depends on the ability to make
the correct decisions and take the appropriate actions
during routine occurrences, as well as abnormal
situations. The influence of alcohol drastically reduces
the chances of completing a flight without incident.
Even in small amounts, alcohol can impair judgment,
decrease sense of responsibility, affect coo rdination,
constrict visual field, diminish memory, reduce
reasoning ability, and lower attention span. As little as
one ounce of alcohol can decrease the speed and
strength of muscular reflexes, lessen the efficiency of
eye movements while reading, and increase the
frequency at which errors are committed.
Impairments in vision and hearing can occur from
consuming as little as one drink.
While experiencing a hangover, a pilot is still under
the influence of alcohol. Although a pilot may think he
or she is functioning normally, motor and mental
response impairment is still present. Considerable
amounts of alcohol can remain in the body for over 16
hours, so pilots should be cautious about flying too soon after drinking.
Figure 9-1. Impairment scale with alcohol use.
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Remote Pilot – Small Unmanned Aircraft Systems Study Guide 50
Intoxication is determined by the amount of alcohol in the bloodstream. This is usually measured as
a percentage by weight in the blood. 14 CFR part 91 requires that blood alcohol level be less than
.04 percent and that 8 hours pass between drinking alcohol and piloting an aircraft. A pilot with a
blood alcohol level of .04 percent or greater after 8 hours cannot fly until the blood alcohol falls
below that amount. Even though blood alcohol may be well below .04 percent, a pilot cannot fly
sooner than 8 hours after drinking alcohol. Although the regulations are quite specific, it is a good
idea to be more conservative than the regulations.
Vision and Flight
The more a pilot understands about the eyes and how they function, the easier it is to use vision
effectively and compensate for potential problems.
Scanning Techniques
To scan effectively, pilots must look from right to left or left to right. They should begin scanning at
the greatest distance an object can be perceived (top) and move inward toward the position of the
aircraft (bottom). For each stop, an area approximately 30° wide should be scanned. The duration of
each stop is based on the degree of detail that is required, but no stop should last longer than 2 to 3
seconds. When moving from one viewing point to the next, pilots should overlap the previous field
of view by 10°. [Figure 9-2]
Figure 9-2. Scanning techniques.
Remote Pilot – Small Unmanned Aircraft Systems Study Guide 51
Chapter 10:
Aeronautical Decision-Making and Judgment
Introduction
Aeronautical decision-making (ADM) is decision-making in a unique environment—aviation. It is a
systematic approach to the mental process used by pilots to consistently determine the best course of
action in response to a given set of circumstances. It is what a pilot intends to do based on the latest
information he or she has.
The importance of learning and understanding effective ADM skills cannot be overemphasized. While
progress is continually being made in the advancement of pilot training methods, aircraft equipment
and systems, and services for pilots, accidents still occur. Despite all the changes in technology to
improve flight safety, one factor remains the same: the human factor which leads to errors. It is
estimated that approximately 80 percent of all aviation accidents are related to human factors and the
vast majority of these accidents occur during landing (24.1 percent) and takeoff (23.4 percent).
ADM is a systematic approach to risk assessment and stress management. To understand ADM is to
also understand how personal attitudes can influence decision-making and how those attitudes can be
modified to enhance safety in the operation of a small UA. It is important to understand the factors
that cause humans to make decisions and how the decision-making process not only works, but can be
improved.
History of ADM
For over 25 years, the importance of good pilot judgment, or aeronautical decision-making (ADM), has
been recognized as critical to the safe operation of aircraft, as well as accident avoidance. The airline
industry, motivated by the need to reduce accidents caused by human factors, developed the first
training programs based on improving ADM. Crew resource management (CRM) training for flight
crews is focused on the effective use of all available resources: human resources, hardware, and
information supporting ADM to facilitate crew cooperation and improve decision-making. The goal of
all flight crews is good ADM and the use of CRM is one way to make good decisions.
Research in this area prompted the Federal Aviation Administration (FAA) to produce training directed
at improving the decision-making of pilots and led to current FAA regulations that require that
decision-making be taught as part of the pilot training curriculum. Aeronautical Decision Making and
Risk Management are topics that the FAA is required to test an applicant about for the issuance of an
sUAS certificate. ADM research, development, and testing culminated in 1987 with the publication of
six manuals oriented to the decision-making needs of variously rated pilots. These manuals provided
multifaceted materials designed to reduce the number of decision-related accidents. The effectiveness
of these materials was validated in independent studies where student pilots received such training in
conjunction with the standard flying curriculum. When tested, the pilots who had received ADM-
training made fewer inflight errors than those who had not received ADM training. The differences
were statistically significant and ranged from about 10 to 50 percent fewer judgment errors. In the
operational environment, an operator flying about 400,000 hours annually demonstrated a 54 percent
reduction in accident rate after using these materials for recurrency training.
Chapter 10: Aeronautical Decision-Making and Judgment
Remote Pilot – Small Unmanned Aircraft Systems Study Guide 52
Contrary to popular opinion, good judgment can be taught. Tradition held that good judgment was a
natural by-product of experience, but as pilots continued to log accident-free flight hours, a
corresponding increase of good judgment was assumed. Building upon the foundation of conventional
decision-making, ADM enhances the process to decrease the probability of human error and increase
the probability of a safe flight. ADM provides a structured, systematic approach to analyzing changes
that occur during a flight and how these changes might affect the safe outcome of a flight. The ADM
process addresses all aspects of decision-making and identifies the steps involved in good decision-
making.
Steps for good decision-making are:
1. Identifying personal attitudes hazardous to safe flight.
2. Learning behavior modification techniques.
3. Learning how to recognize and cope with stress.
4. Developing risk assessment skills.
5. Using all resources.
6. Evaluating the effectiveness of one’s ADM skills.
Risk Management
The goal of risk management is to proactively identify
safety-related hazards and mitigate the associated
risks. Risk management is an important component of
ADM. When a pilot follows good decision -making
practices, the inherent risk in a flight is reduced or even
eliminated. The ability to make good decisions is based
upon direct or indirect experience and education. The
formal risk management decision -making process
involves six steps as shown in Figure 10-1.
Consider automotive seat belt use. In just tw o decades,
seat belt use has become the norm, placing those who
do not wear seat belts outside the norm, but this group
may learn to wear a seat belt by either direct or
indirect experience. For example, a driver learns
through direct experience about the value of wearing a
seat belt when he or she is involved in a car accident
that leads to a personal injury. An indirect learning
experience occurs when a loved one is injured during a
car accident because he or she failed to wear a seat
belt.
As you work through the ADM cycle, it is important to remember the four fundamental principles of
risk management.
1. Accept no unnecessary risk. Flying is not possible without risk, but unnecessary risk comes
without a corresponding return.
2. Make risk decisions at the appropriate level. Risk decisions should be made by the person
who can develop and implement risk controls.
3. Accept risk when benefits outweigh dangers (costs).
Figure 10-1. Risk management decision-making process.