Human factors in aviation


pilot performance factors in decision making



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pilot performance factors in decision making

Aeronautical knowledge, skill and judgment have been considered the three essential faculties that pilots must possess to be professional in the execution of their duties. The knowledge and skill have been taught in ground school and flight training programs, but decision making skills have usually been considered a trait that pilots innately possess or that is acquired through experience. In fact, good decision making skills can also be taught.

Training in decision making skills is being introduced as a part of the pilot training program. Pilots can learn good judgment just as thoroughly as they learn the mechanical concepts and basic skills of flying. But what is good judgment? It is the ability to make an instant decision which assures the safest possible continuation of the flight.

"Pilot judgment is the process of recognizing and analyzing all available information about oneself, the aircraft and the flying environment, followed by the rational evaluation of alternatives to implement a timely decision which maximizes safety. Pilot judgement thus involves one's attitudes toward risk-taking and one's ability to evaluate risks and make decisions based upon one's knowledge, skills and experience. A judgment decision always involves a problem or choice, an unknown element, usually a time constraint, and stress. " (Transport Canada: Judgment Training Manual).

The causal factor in about 80% to 85% of civil aviation accidents; is the human element, in other words, pilot error, a poor decision or a series of poor decisions made by the pilot-in-command. This concept is known as the poor judgment chain. One poor decision increases the probability of another and as the poor judgment chain grows, the probability of a safe flight decreases. The judgment training program teaches techniques; for breaking the chain by teaching the pilot to, recognize the combination of events that result in an accident and to deal with the situation correctly in time to prevent the accident from occurring.

How a pilot handles his or her responsibilities as a Pilot depends on attitude. Attitudes are learned. They can be developed through training into a mental framework that encourages good pilot judgment.

The pilot decision making training program is based on recognition of five, hazardous attitudes.

Anti-authority. This attitude is common in those who do not like anyone telling them what to do.

Resignation. Some people do not see themselves as making a great deal of difference in what happens to them and will go along with anything that happens.

Impulsivity. Some people need to do something, anything, immediately without stopping to think about what is the best action to take.

Invulnerability. Some people feel that accidents happen to other people but never to themselves. Pilots who think like this are more likely to take unwise risks.

Macho. Some people need to always prove that they are better than anyone else and take risks to prove themselves and impress others.

Pilots who learn to recognize these hazardous attitudes in themselves can also learn how to counteract them, can learn to control their first instinctive response and can learn to make a rational judgment based on good common sense.

The DECIDE acronym was developed to assist a pilot in the decision making process.

D - detect change.

E - estimate the significance of the change.

C - choose the outcome objective.

l - identify plausible action options.

D - do the best action.

E - evaluate the progress.

Using the DECIDE process requires the pilot to contemplate the outcome of the action taken. The successful outcome should be the action that will result in no damage to the aircraft or injury to the occupants.

When a pilot receives a license to fly, he is being given the privilege to use public airspace and air navigation facilities. He is expected to adhere to the rules and to operate an aircraft safely and carefully. He is expected to use good judgment and act responsibly. Decision- making is a continuous adjustive process that starts before take-off and does not stop until after the final landing is made safely. Positive attitudes toward flying, learned judgment skills, will improve a pilot's chances of having a long and safe flying career.

B.  human factors summary

The human factor is the most flexible, adaptable and valuable part of the aviation system. but it is also the most vulnerable to influences which can adversely affect its performance. Optimising the role of people in the aviation environment involves ail aspects of human performance and behaviour: decision making, the design of displays and controls and the cabin layout, and even the design of aircraft operating manuals, checklists and computer software.

Human factors is about people in their living and working situations, about their relationships with machines, with procedures, with the environment about them and with other people.

In most cases, accidents result from performance errors made by healthy and properly certificated individuals. The sources of some of these errors may be traced to poor equipment or procedure design or to inadequate training or operating instructions. Reduced levels of human performance capability and limitations in human behaviour result in less than optimum performance

There would appear to be a direct relationship between workload and performance. At low levels of workload, such as during the cruise phase of long haul flights, performance is poor and the ability to react in an emergency is potentially negatively affected. The standard of performance increases as workload increases up to an optimum level of workload and performance. At extremely high levels of workload (overload), performance is again jeopardized. In the aviation industry, the concept of workload is of primary importance to-ensure that the demands of the task never exceed the capabilities of the pilot.

Recognition of human factors; is based on the effectiveness, the safety and the efficiency of the system and on the well being of crew members.

The central figure in the human factors equation is the pilot, or other crew member, who is the most critical but also the most flexible component of the system. However, people have limitations and are subject to considerable variations in performance.

Design of cockpit space is important to pilot performance. Comfortable seats designed to fit the human body, instrument displays designed to match the sensory and information processing characteristics of the user, controls with standardized movement, coding and location, are recognized as important factors in providing a compatible and comfortable working environment. Ail too often, pilot error can be attributed to knobs and levers that are, poorly located, that operate differently from one airplane to another, that are improperly coded.

The non- physical aspects, such as procedures, manuals and checklists, symbology and computer programs, are responsible for delays and errors if these are confusing, misleading or excessively cluttered in their presentation and documentation.

The effect of environmental factors, such as noise, heat, lighting and vibration, are recognized as causal factors in human error. More serious problems are associated with disturbed biological rhythms and related sleep disturbance and deprivation. The body operates on a circadian, or 24 hour, rhythm which is related to the earth's rotation time. It is maintained principally by the cycles of light and darkness, but also by meals and physical and social activities. Safety, efficiency and well being are affected by the disturbed pattern of biological rhythms occasioned by long range flight, irregular schedules and late night flights. Long distance trans-meridian air travel, especially, is responsible for sleep disturbance, disruption of eating and elimination habits that result in lassitude, anxiety, irritability and depression, ail symptoms of what is commonly called jet lag. Wide differences are found amongst individuals in their ability to sleep out of phase with their biological rhythms. The use of drugs or tranquillizers; to induce sleep is not recommended as they have a lasting adverse effect on later performance. The use of alcohol is also not recommended since it is a drug, a depressant and, while it does induce sleep, it interferes with deep sleep.

Traditionally, crew members have been trained individually and it was assumed that individually proficient crew members; would be proficient and effective members of a crew team. However, flight crews function as groups and group influences play a role in determining behaviour and performance. Leadership, crew cooperation, teamwork and personality interaction are vital factors; in cockpit resource management. Training programs aimed at increasing the co-operation and communication between crew members; are vital in ensuring efficient and safe airplane operation. Cockpit resource management training focuses on the functioning of the flight crew as an intact team and provides; opportunities for crew members; to practice their skills together. The program teaches crew members how to use their own personal and leadership styles in ways to foster crew effectiveness.


the effects of dehydration on pilot performance
By Nina Anderson www.longlifecatalogs.com

(Nina Anderson is a Hawker pilot, FAA Wings Program human factors seminar leader and ISSA Specialist in Performance Nutrition.)

There is scant attention given to it. Most pilots overlook it. Some shrug it off. While others simply don’t know about its effects in the cockpit. The problem? Pilot dehydration. Most pilots are unaware of its devastating effects and symptoms, which can increase the risk of aircraft incidents and accidents, even during a mildly warm day. So in order to heighten general aviation’s awareness of this often-overlooked condition, the Federal Aviation Administration (FAA) has recently added pilot dehydration to its list of physiological conditions found in the latest Practical Test Standards—its symptoms, causes, effects and corrective actions. It believes that educating pilots about dehydration will not only decrease aircraft incidents, but also save your life one day. 

Most pilots associate dehydration with thirst and assume that an easy fix is just to drink any type of liquid. This is not always the case. A pilot’s dehydration condition can be caused by a lack of water within the body cavity due to high body temperatures, a dry aircraft environment, excess caffeine, antihistamines, inappropriate fluid intake and other factors. Many soft drinks, teas and juice drinks do not constitute good hydration substitutes, as they contain caffeine and sugar that may compromise absorption of the water content. 

Hot cockpits and flight lines also cause dehydration. The 130-degree ramp at Phoenix, Arizona., for example, is an obvious cause of dehydration. But what about the 72-degree cockpit? Pilots should concern themselves in that environment, too, since average humidity in the cockpit is low, causing a dramatic increase in fluid loss. 

Everyone must be aware that un-replaced water losses equal two percent of body weight and will impact your body’s ability to regulate heat. At three percent loss, there is a decrease in muscle cell contraction times. When fluid losses equal four percent of body weight, there is a five to 10 percent drop in overall performance, which can last up to four hours.

According to the Spring 2000 edition of the Federal Air Surgeon Bulletin, there are three stages of heat exhaustion that lead to dehydration: Heat stress, when the body temperature is at 99.5 to 100 degrees Fahrenheit; Heat exhaustion, when the body temperature is at 101 to 105 degrees Fahrenheit; and Heat stroke, when the body temperature is more than 105 degrees Fahrenheit. There’s a possibility that there’s a subtle change between one stage to another, so you need to be extra careful and continually monitor your condition when flying in hot-weather conditions. 

The symptoms of dehydration go beyond thirst. In an effort to respond to the brain’s need for fluid, the kidneys reabsorb water through the urine, creating fluid retention and frequent urges to visit the bathroom. Dry skin is also an indicator of dehydration, as the skin gets most of its moisture subdermally. The brain is 75 percent water and, when it needs to replace lost fluid, it can manifest certain symptoms, such as headaches, light-headedness and fatigue. Dehydration also contributes to fuzzy thinking, poor decision-making, dizziness and muscle fatigue. Long-term effects include wrinkled skin, impaired memory function, dry hair, brittle nails, constipation, susceptibility to colds and, because of extremely dry nasal passages, sinus infections. 

So how do you avoid dehydration in the cockpit? You’ll need to permanently attach yourself to a water bottle and drink from it regularly. The Federal Air Surgeon Bulletin suggests drinking cool, 40-degree Fahrenheit water before feeling thirsty. This will help you stay ahead of the game, keeping you hydrated before the “thirst mechanism” sets in.  

But for some, plain bottled water might be offensive. So one alternative to water is to simply drink mineralized (electrolyte) water. Electrolyte drinks, more commonly known as sports drinks, are generally designed to replace the fluids (water) and electrolytes (sodium, potassium, chromium, manganese, etc.) lost during stress, body temperature regulation and exercise. Most contain sugars which may lower a pilots systemic blood-sugar levels and precipitate fatigue.  

The FAA also suggests staying away from coffee, sodas and teas—otherwise called diuretic drinks. These beverages contain caffeine, alcohol and carbonation, which causes excess urine production or decreased voluntary fluid intake—a sure sign of dehydration. In addition, don’t over-exercise before a flight, since it can cause a large amount of body fluid loss that is difficult to replace quickly. You also need to keep in mind that acclimation to a major change in weather takes one to two weeks, which can drastically affect your flying abilities. Monitoring personal effects of aging, recent illness, fever, diarrhoea or vomiting can also help you in gauging whether or not you’re dehydrated.

But, perhaps, the most important factor in preventing dehydration is to continually be aware of your physiological and environmental conditions. This will help to maintain your rehydration water intake and prevent you from progressing into heat exhaustion and even heat stroke. It’s a good plan for a problem that can easily be avoided—all with just a few gulps of water. 



The Three Stages Of Heat Exhaustion 

1.   Heat stress (99.5° to 100° F body temperature) reduces:

·        Performance, dexterity and coordination
·        Ability to make quick decisions
·        Alertness
·        Visual capabilities
·        Caution and caring

2.   Heat exhaustion (101° to 105° F body temperature) symptoms:

·        Fatigue
·        Nausea/vomiting
·        Giddiness
·        Cramps
·        Rapid breathing
·        Fainting 

3.   Heat stroke (above-105° F body temperature) symptoms:

·        Body’s heat control mechanism stops working

·        Mental confusion

·        Disorientation

·        Bizarre behaviour



·        Coma


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