ATPL Human Performance & Limitations

8/12/2019 ATPL Human Performance & Limitations

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Human Performance and Limitations Introduction

Human Factors is about people in their living and working situations; about their relationship with

machines, procedures and the environment. It is also about their relationships with other people. Inaviation, Human Factors involves a set of personal, medical and biological considerations for

operations.

Medical Requirements (JAR-FCL Part 3)

- Fitness: The holder of a medical certificate shall be mentally and physically fit to exercise

safely the privileges of the applicable licence.

- Requirement: In order to apply for/exercise licence privileges, the applicant shall hold a medical

certificate issued and appropriate to the privileges of the licence.

- Disposition: After examination completion, the applicant shall be advised whether fit/unfit orreferred to the Authority. The Authorised Medical Examiner (AME) shall inform

the applicant of any condition(s) that restrict licence privileges. If a restricted

medical certificate is issued, which limits the holder to exercise PIC privileges

only when a safety pilot is carried, the Authority will give advisory information for

use by the safety pilot.

Decrease in Medical Fitness

Licence holders/students shall not exercise the privileges of their licences etc. at any time when they

are aware of any decrease in their medical fitness which might render them unable to safely exercise

those privileges and shall without undue delay seek the advice of the Authority or AME whenbecoming aware of: - Hospital or clinic admission for more than 12 hours.

- Surgical operation or invasive procedure.

- The regular use of medication.

- The need for regular use of correcting lenses.

Every holder of a medical certificate who is aware of:

- Any significant personal injury involving incapacity to function as a member of a flight crew.

- Any illness involving incapacity to function as flight crew for a period of 21 days or more.

- Being pregnant.

Shall inform the Authority in writing of such injury/pregnancy, and as soon as the period of 21 dayshas elapsed in the case of illness. The medical certificate shall be deemed to be suspended upon

occurrence.

For illness/injury the suspension will be lifted after medical examination and pronounced fit to

function as a flight crew member.

In case of pregnancy, the suspension may be l ifted by the Authority for such period and subject to

such conditions as it thinks fit. Will cease after pregnancy ended and pronounced fit to resume.

Some additional factors which affect the normal working of a human body in flight:

- Fatigue (sleep disturbances/jet lag) - Blood Donations

- Nutrition - Drugs (including caffeine/nicotine)

- Alcohol - Stress


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Accidents

Accident Reports

Accident investigations improved aircraft design, and later also ATC, resulting in a steady decline in

accidents. This continuous decline has been attributed to the constant improvement of equipment,

better training and operating procedures. Today, 2 out of 3 accidents are caused by human related

actions.

Human Error

Encompasses pilots, cabin crew, dispatchers, ground crew, maintenance personnel, ATC and

manufacturers. Human Error accidents have increased. Current research indicates inadequate

training is the main cause (but not technical training). Studies indicate more training in leadership,

communication and teamwork are needed.

Crew Resource Management (CRM)

CRM covers a wide variety of skills: - Interpersonal human skills.- Decision Making.

- Teamwork.

- Situational Awareness.

- Stress.

- Workload Management.

CRM represents an approach to improving aviation safety that was born from real-life experiences of

airline pilots. They realised technical skills were not enough to safely manage a complex flight

system. The list of critical situations where good human performance and teamwork saved the day is

lengthy. There have been many accidents where the cockpit and cabin crews hard efforts havesaved many lives.

Flight Safety Concepts

The SHEL Model

Illustrates the different elements of Human Factors.

First developed in 1972 by Edwards.

SSoftware

HHardware

EEnvironment

LLiveware

Liveware

The centre of the model is a person, the most critical and

flexible component in the system. However, people are

subject to significant variations in performance and suffer

limitations but most are now predictable in general terms.

The block edges are not straight and simple. The other components must be carefully matched to

them if stress in the system is to be avoided.


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Physical Size and Shape

Vital role played in the design of the workplace and most equipment. Movements and

measurements vary according to age, ethnic and gender groups. Normally aircraft are designed

around 90% of the population (ignoring the top and bottom 5%).

Anthropometry:The comparative study of sizes and proportions of the human body.

Input Characteristics

Humans have a sensory system for collecting information from surroundings enabling response to

external events. However, all senses are subject to degradation.

Information Processing

Poor instrument and warning system design has resulted from failure to take into account the

capabilities and limitations of the human information processing system.

Output Characteristics

Once information is sensed and processed, messages are sent to the muscles to initiate the desiredresponse (physical control movement/communication).

Liveware-Hardware Interaction

Elements:Controls and Displays (design, interpretation, control, standardisation).

Alerting/Warning Systems (false indications, distractions, response, selection).

Personal Comfort (temperature, illumination, seat position, cockpit visibility).

Skills:Scanning, detection,, decision making, situational awareness, vigilance.

Liveware-Software Interaction

Elements:SOPs, Written Materials/Software, Maps/Charts, Checklists/Manuals, Automation.

Skills:Computer literacy, self-discipline, time management, task allocation.

Liveware-Environment Interaction

Elements:Temperature, Pressure, Humidity, Noise, Lighting, Radiation, Wx, Terrain, Time of Day.

Skills:Adaptation, observation, stress/risk management, prioritisation.

Liveware-Liveware Interaction

Elements:Human Errors/Reliability, Workload, Information Processing, Attitude Factors, Experience.

Skills:Communication, observation, listening, management, problem solving, perception.

Atmosphere and Physics

Gases of the Atmosphere

Nitrogen (N)78.08%

Most plentiful gas in the atmosphere but not readily used by the human body. Can cause evolved

gas problems by saturating body cells and tissues.

Oxygen (O)20.94%

Second most plentiful gas in the atmosphere. A by-product of photosynthesis renewing the supply of

oxygen in the atmosphere every 3,000 years. During metabolism, the human body uses oxygen to

convert body fuels into energy.


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Carbon Dioxide (CO)0.03%

Although small in amount, it is still critical to life. Plants use carbon dioxide for photosynthesis and is

a by-product of human metabolism. The carbon dioxide supply is renewed every 8 years.

Other Gases

Argon (Ar)0.93%

Neon, Helium, Krypton, Xenon, Hydrogen,

Ammonia0.95%

The Standard Atmosphere

Barometric Pressure:The weight/force exerted by

the atmosphere at any given point.

ISA:The average conditions for all

seasons/latitudes/altitudes in the atmosphere.

- Relationship between pressure and altitude.

Standard Atmospheric Pressures and Temperatures

Altitude (ft) Pressure (mmHg) Temperature (C)

40,000 141 -56.5

33,700 190 -52

27,500 253 -40

18,000378

(50% compared to SL)-21

10,000 523 -05

Sea Level 760 +15

Partial Pressure

Each gas in a mixture of gases behaves as if it alone occupied the total volume and exerts a pressure.

Physiological Zone (Sea Level10,000ft)

The atmospheric zone in which the human body is well adapted. Changes in pressures with rapid

ascents/descents within this zone can produce ear/sinus trapped gas problems.

Physiologically Deficient Zone (10,00050,000ft)

Decreased barometric pressure results in sufficient oxygen deficiency to cause hypoxia. Additionalproblems may arise from trapped/evolved gases. Protective oxygen equipment is necessary.

Space Equivalent Zone (60,000ft120 miles)

Supplemental 100% oxygen no longer protects humans from hypoxia (pressure suits and sealed

cabins are required). Unprotected humans may suffer radiation effects and boiling of body fluids.

Daltons Law (Relations of Partial Pressures)

The sum of the partial pressures of individual gases is equal to total pressure.

PL= + +

To calculate pp of one of the gasses: Divide the gas % by 100 x Total pressure (at that altitude).


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Pressure Change Effects

The human body can withstand enormous changes in barometric pressure as long as the air pressure

in the body cavities equals ambient air pressure. Difficulty occurs when the expanding gas cannot

escape to allow equalisation. Body gas expansion causes dysbarism (gas expansion manifestations

trapped/evolved).

Trapped Gas Disorders

If gas expansion is impeded, pressure builds up within the cavity and pain is experienced.

Barotrauma:Abdominal, ear, sinus pain or toothache.

oyles Law (Relation between Pressure and Volume)

The volume of a gas is inversely proportional to the pressure exerted upon it (temperature

constant).

P x V = C P = Pressure V = Volume C = Constant OR

P

P =

V

V

Gastrointestinal Tract Trapped Gas Disorders

Severe pain experienced above 25,000ft caused by distension of stomach, large and small intestines.

Source of gas is swallowed air and as a result of digestion. Can produce marked lowering of blood

pressure and loss of consciousness if distension is not relived. Watch for pallor/signs of fainting.

Diet

Foods which produce gas include: onions, cabbages, apples, radishes, cucumbers, melons.

Crew participating in high altitude flights should avoid these foods as well as carbonated drinks.Irregular and hasty eating (or eating while working) makes individuals more susceptible.

If trapped problems exist in the gastrointestinal tract at high altitude, belching/passing flatus

relieves the pain (eating/drinking aggravates discomfort).

Ear Trapped Gas Disorders (Ohitic Barotrauma)

As pressure reduces during ascent, the air in the middle ear is intermittently released through the

Eustachian tube into the nasal passages. As inside pressure increases, the eardrum bulges and some

air is forced out of the middle ear causing a pop/click (eardrum resumes normal position).

During descent, the pressure changes may not occur automatically (Eustachian tube resists opposite

direction flow). The pressure difference causes the eardrum to be forced inwards. This can makeopening the Eustachian tube impossible causing pain. The eardrum could rupture.

Pain could increase with further descent and ascent could be required for pressure equalisation

before a slow descent. Greatest pressure changes between sea level and 5,000ft.

Delayed Ear Block

Caused by saturation of middle ear with oxygen (when breathing pure oxygen) and can develop

several hours after landing. The pressure inside the ear becomes less than outside causing mild pain.

Can be relieved by performing the Valsalva.


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- Pressure change effect on the middle ear

Complications from Pre-existing Physical Conditions

Eustachian tube inflammation/infection from a head cold, sore throat, middle ear infection, sinusitis,or tonsillitis can cause the middle ear to not be adequately ventilated. Forceful opening of the tube

could carry the infection to the middle ear. If flight is essential, slow descents are preferred.

Malposition of the temporal bone and jaw may cause ear pain. Swallowing or yawing can equalise

the pressure during descent. If this does not work them perform the Valsalva (NEVER during ascent).

If middle ear/ambient pressures have not equalised after landing and pain persists consult a doctor

since barotitis media can occur.

Sinus Trapped Gas Disorders

Sinuses are air-filled, relatively rigid, bony cavities lined with mucous membranes connected to the

nose by small openings. If normal, air passes into/out of the cavities without difficulty equalising thepressure. If obstructed (infection/allergic condition) this causes a pressure differential which

sometimes causes severe pain. Like ears, they are most affected in the later stages of descent.

Frontal:Pain extends over the forehead above the bridge of the nose.

Maxillary:Pain either side of the nose (cheekbones) and possibly in the upper jaw.

Perform Valsalva during the descent. If pain is noticed on ascent, any further climb should be

avoided. Same for descent. If oxygen equipped, use under positive-pressure to ventilate the sinuses.

If not clear after landing, consult a doctor.

- Location of sinus and cavities


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Teeth Trapped Gas Disorders (Aerodontalgia)

Toothache usually results from an existing dental problem. Generally occurs from 5,000-15,000ft.

The altitude at which this takes is consistent for the individual. Descent will bring relief from pain but

also often disappears at the same altitude which it first occurred.

Evolved Gas Disorders

Occur in flight as a direct result of a reduction in atmospheric pressure. Gases dissolved in body

fluids at sea-level pressure are released from the solution and enter a gaseous state as bubbles

when ambient pressure is lowered. This causes various disorders (decompression sickness).

Henrys Law

The amount of gas dissolved in a solution is directly proportional to the pressure of the gas over the

solution.

Nitrogen Saturation (Decompression Sickness)

Tissues and fluids of the body contain 11.5 litres of dissolved nitrogen. As altitude increases, the

partial pressure of atmospheric nitrogen decreases and nitrogen diffuses from the body so

equilibrium can be reached. If this change is rapid, there is a lag in recovery of equilibrium leaving

the body supersaturated. The excess nitrogen diffuses into the blood. With rapid ascent to >30,000ft

the nitrogen forms bubbles especially in tissues with fat.

Symptoms: Pain in joints/related tissues, shortness of breath, sensation of suffocation, bluish skin

colouration, skin itching, cold, headache, partial paralysis, loss of consciousness.

Evolved gas disorders are considered medical emergencies.

The risk can be reduced by pre-oxygenation (pilot breathing 100% pure oxygen for a period prior to

high altitude exposure).

If symptoms appear in flight, descent to ground level must be immediately conducted and place the

affected individual on 100% oxygen to remove excess nitrogen from the system.

Bends:Bubbles in the joints (shoulder, elbow, wrist, knee, ankle, rarely hips)

Creeps:Bubbles in the skin.

Chokes:Bubbles in the lungs.Staggers:Bubbles in the brain.


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Pressurisation of Cabin

Usually maintained at a pressure equivalent to an altitude of 10,000ft. The altitude threshold for

the onset of decompression sickness is 18,000ft.

Scuba Diving

If you fly in an aircraft following scuba diving or any underwater activity using compressed air, excess

nitrogen can have been absorbed into the blood and tissues (depends on depth/duration of

exposure).

Individuals should not fly within 12 hoursfollowing diving using compressed air.

The time limit increases to 24 hoursif the dive depth is greater than 10 metres.

harles Law

The volume of a fixed mass of gas is directly proportional to its absolute temperature provided the

pressure remains constant.

General Gas Law

(PV)= (PV)

P = Pressure V = Volume T = Temperature

Flicks Law

The rate of gas transfer is proportional to the area of the tissue and the difference between the

partial pressures of the gas on the two sides, and inversely proportional to the thickness of the

tissue.

Respiratory and Circulatory Systems

- Components of the Respiratory and Circulatory Systems


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Respiratory System

Primary function is the intake of Owhich enters through the respiratory system and transported in

the body through the circulatory system. All body cells require O to metabolise food.

Respiration:Process of breathing in O rich air and breathing outO poor air.

Components of the Respiratory System

Oral-Nasal Passage:Includes mouth/nasal cavities. Mucous membrane hairs filter air as it enters.

Pharynx:The back of the throat connected to oral/nasal cavities. Humidifies and warms air entering.

Trachea:Windpipe which moves air into the bronchi. Air moves into smaller ducts entering alveoli.

Alveoli:Surrounded by capillaries (joining arteries/veins) allowing RBCs to move through allowing

gaseous exchange within. COand Omove in/out of the alveoli due to pressure differentials. As the

blood travels through the capillaries, the O flows from high pressure (alveoli) to low (in the blood).

CO diffuses from the blood to the alveoli in the same way.

The amount of O/CO transferred depends on the pressures of the alveoli and arteries which

decreases as altitude increases (O saturation in the blood decreasesleading to hypoxia).

Carbon Dioxide Removal

A by-product of the metabolic process. It is dissolved in blood plasma from tissues to the lungs.

Autoregulation

Receptor cells in the brain and sensitive to the level of COand acids in the blood, control the rate

and volume of breathing. Too high levels trigger and increase in breathing (greater volume) until

levels are normal.

Other body receptors monitor the levels of Oand COleaving the lungs. When Opartial pressure

falls it triggers an increase in breathing. Low Olevels by themselves may not increase breathing rate

until a dangerously low Opartial pressure has been reached.

Body Heat Balance

Body temperature must be maintained around 36.9C (98.4F).

Body Chemical Balance (Oand CO)

Normal body pH level is 7.4 (slightly alkaline). Any shift from the narrow limits is sensed by the brain

and chemical receptors trigger the respiratory system to return the pH to normal limits.


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Composition of Air in the Lungs

Tidal Volume:Adult breathes in/out 12-15 times a minute (0.35-0.65 litres of air each breath).

Tracheal Air:Inhaled air becomes saturated with water vapour and warmed to body temperature.

Alveolar Air:Enters the lungs (delivers O/receives CO). Known as external respiration.

Lung Volumes

Tidal:The amount of air that moves into the lungs with each inspiration (or outexpiration).

Inspiratory Reserve:Air inspired with a maximal effort in excess of tidal volume.

Expiratory Reserve:Volume expelled by an active respiratory effort after passive expiration.

Residual:Air left in the lungs after maximal expiratory effort.

Respiratory Dead Space:Space in the conducting zone of airways not exchanging in the alveoli.

Vital Capacity:Largest amount of air that can be expired after a maximal inspiratory effort.

Maximal Breathing Capacity:Largest volume of gas moved into/out of the lungs in 1 minute.

Circulatory System

Primary function is to maintain equilibrium of fluids in the body. It also regulates body chemical

balance and provides cell nutrition, body excretion, and body heat exchange.

Components of the Circulatory System

Heart: Made up of 4 chambers; Atria (left/right) and Ventricles (left/right).

Right-side:Pumps Opoor blood (cellslungs). Left-side:Receives Orich blood (lungscells).

Arteries:Vessels which move blood from the heart to the tissues.

Aorta:Conveys Orich blood from the left ventricle to the body.

Pulmonary Artery:Conveys blood from the right ventricle to the lungs.

Veins:Vessels which return blood to the heart.

Capillaries:Connect arteries to veins. Transfer O, CO, nutrients and waste between cells and blood.

Baroreceptors:Stretch receptors monitoring/maintaining blood pressure when alterations occur.

Factors Affecting Heart Rate

Accelerated:Inspiration, hypoxia, painful stimuli, fever, increased activity, thyroid hormones.

Decelerated:Expiration, fear, grief, increase in intracranial pressure.

Blood Pressure

The heart beats around 70x/min at rest which produces an arterial pulse causing a pressure increase

(peak = systolic pressure). The pressure then falls (minimum = diastolic pressure) as the heart relaxes

(allows blood to flow into heart).Measured in mmHg. Normal reading: 120/80 (120 = systolic/80 = diastolic).

Regulated automatically by carotid/aortic sinus pressoreceptors which detect pressure changes.

Hypertension (High Blood Pressure)

Symptoms:Headache and distorted vision but often symptomless until organ damage occurs.

Causes:Being male, positive family history, smoking, diabetes, alcohol, obesity.

Treatment:Antihypertensive medications (if diastolic pressure >100 on at least 3 readings).

Hypotension (Low Blood Pressure)/Circulatory Shock

Symptoms:Dizziness, blurred vision, weakness/fatigue/nausea, cognitive impairment, neck ache.

Causes:Heart failure, bleeding, fluid loss, allergic reactions, infections, heat exposure, certain drugs.


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Coronary Artery Disease/Angina

Narrowing of coronary arteries. Angina is a symptom of reduced O supply to the heart.

Makes an individual susceptible to myocardial infarction and cardiac arrest.

Symptoms:Crushing chest pain (may radiate to jaw, neck, one/both arm(s) after exertion/stress).

Causes:Positive family history, smoking, hypertension, high cholesterol, lack of exercise, diabetes.

Myocardial Infarction

Blockage of the coronary artery by a thrombus (clot) usually in an already compromised vessel.

May or may not be painful but will cause damage to the heart muscle.

Cardiac Arrest

Sudden inability of the heart to function.

Causes:Myocardial infarction, pulmonary embolism, trauma, shock, hypoxia, hypothermia.

Anaemia

Causes:Inadequate delivery of O to body tissues from abnormal reduction of haemoglobin. Symptoms:Low energy, dizziness, shortness of breath, pallor, digestive disorders.

Stroke

Occurs when blood supply to a certain part of the brain is cut off. Hypertension is a risk factor.

Victim may experience memory loss or be unable to walk (depending on affected part of brain).

Causes: HaemorrhagicRuptured blood vessels (placing pressure on the brain).

IschemicBlocked arteries (starving areas of the brain controlling sight, speech, movement)

Components and Functions of Blood

Red Blood Cells:Transport O in haemoglobin. Cells produced in bone marrow.

White Blood Cells:Fight inflammation/infection. Small size enables movement through capillaries.

Platelets:Aid in coagulating blood and maintaining the circulatory system.

Plasma:Transports CO, nutrients and hormones. Composed of water, protein and salts.

Hyoxia (Insufficient in the bloodstream)usually occurs +10,000ft

Hypoxic Hypoxia

Insufficient O in breathed air or when conditions prevent diffusion of O from the lungs to the

bloodstream. Most likely encountered at high altitudes.

Prevented by ensuring sufficient O is available (limiting time at altitude, pressurisation, O masks).

Anaemic Hypoxia

Reduction in the O carrying capacity of the blood. Anaemia/blood loss are the most common

causes. Carbon monoxide, nitrites and sulpha drugs also cause hypoxia by reducing haemoglobin.

Stagnant Hypoxia

O carrying capacity of the blood is adequatebut there is inadequate circulation. Heart failure,

arterial spasm, occlusion of a blood vessel and venous pooling (during +G manoeuvres) cause this.

Histotoxic Hypoxia

Interference with the use of O by body tissues. Alcohol, narcotics and certain poisons (cyanide)

interfere with the cells ability to use an adequate supply of O.


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- Possible signs and symptoms of hypoxia

Individual Susceptibility Factors

Smoking and alcohol increase the physiological altitude of the body. Also greatly influenced by;

metabolic rate (increased by temperature extremes), diet, physical fitness (greater condition =

higher tolerance) nutrition, and emotions. These determine whether hypoxia develops at a

lower/higher altitude than usual.

Exposure Duration

The longer the duration of exposure, the more detrimental the effect of hypoxia. However, the

higher the altitude, the shorter the exposure before hypoxia symptoms occur.

Effects of Hypoxia

Nerve tissue has a heavy requirement for O and brain tissue is the first to be affected by any

deficiency. If this is prolonged/severe, brain death occurs and the cells can never regenerate.

Time of Useful Consciousness (TUC)

The time a crew member has from the interruption of the O supply to the time when the ability to

take corrective action is lost. Varies with rate of decompression and altitude in pressurised aircraft.

Altitude (ft) TUC

20,000 512 minutes

25,000 35 minutes

30,000 12 minutes

35,000 3060 seconds

43,000 912 seconds


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Stages of Hypoxia

Indifferent: Night vision deteriorates at about 4,000ft due to darkness and loss of visual acuity.

Compensatory:Circulatory/respiratory systems provide defence. Can compensate up to 12,000ft.

Above 12,000ft the effects on the nervous system become apparent (10-15 mins).

Drowsiness and judgement errors begin to be made. Co-ordination becomes difficult

Disturbance: Physiological responses can no longer compensate for O deficiency.

Crew members can lose consciousness.

Fatigue, sleepiness, headaches, dizziness, breathlessness, and euphoria are reported

Peripheral and central vision impaired. Weakness/loss of muscle co-ordination.

Thinking is slow (early sign), short-term memory is poor as well as reaction time.

Aggressiveness, overconfidence, or depression can occur.

Stammering and writing illegibly are typical at this stage.

Skin becomes bluish in colour (O molecules fail to attach to haemoglobin).

Critical: Within 3 to 5 minutes, incapacitation and unconsciousness occur.

Limitations of Time at Altitude

Aircraft not O equipped should not fly above 10,000ft for extended periods of time.

14,000ft must never be exceeded in an unpressurised aircraft without supplemental O.

Altitude Required Delivery to Lungs

010,000ft Ambient Air

10,00033,700ft Increasing O concentration

33,70040,000ft 100% O

+ 40,000ft 100% O under positive pressure

Treatment of Hypoxia

Must be treated immediately with 100% O through a mask. If no mask available, descent to below

10,000ft is mandatory.

Carbon Monoxide (CO)

CO has an attraction for haemoglobin 200x greater than O meaning RBCs cannot carry O until all

the CO is expelled. CO prevents O being used by the body and can harm the central nervous system.Is the result of incomplete combustion of fuels and is colourless, tasteless, and odourless. The effects

are cumulative and can take several days for the body to completely recover.

Symptoms:Headaches, dizziness, weakness, nausea, rapid heartbeat, seizures, cardiac arrest,

loss of hearing, blurred vision, vomiting, disorientation, loss of consciousness, death.

Hyperventilationusually occurs


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Symptoms:Dizziness, visual impairment, muscle spasms, tingling/cold/hot sensations,

unconsciousness.

Treatment:Voluntary reduction in respiration rate.

Breathing into a paper bag to re-establish correct CO/O balance.

Heat Strain

Physiological: - Profuse sweating leading to dehydration.

- Peripheral vasodilation (blood vessels dilate).

- Reduction in tolerance to sustained acceleration by around 1G.

- Decrement of vision.

Psychological - Affects memory registration and recall.

- Attention and vigilance reduced.

- Reasoning and decision making takes longer.

- Manual dexterity reduced.

Hyperthermia: - Body sweats to try to reduce temperature (up to 2 litres for brief periods).

- Dehydration and salt depletion unless water and salt intake are increased.

- Heat stroke may result if body temperature not reduced.

Hypothermia: - Body metabolism increased to generate heat (shivering).

- Extra O required to prevent onset of hypoxia.

- Body eventually closes down to conserve heat in vital areas (organs, torso).

Vitamins: - Regulate metabolism of digested food.

- Assist in formation of hormones, blood cells, genetic material.

Fat Soluble Vitamins - Stored in body fat.

- Do not need consuming every day.

A:Derived from carotene (eggs, butter, cheese, carrots, green vegetables).

Affects; vision, skin maintenance, bones, teeth, mucous membranes.

Important for night vision (rod cells).

D:Sunshine vitamin.

Necessary for bone formation and retention of calcium.

E:Plays a part in forming RBCs and muscle.

K:Necessary for blood clotting.

Water Soluble Vitamins- Cannot be stored in the body.- Must be consumed frequently.

B:8Bs (complex).

Affects; metabolism, skin, muscle tone, immune and nervous systems.

C: Important in formation of collagen.

Enhances absorption of iron from vegetables.


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High Altitude Environment

Radiation

The Earths magnetic field deflects many charged particles (solar/cosmic) and is most effective at the

geomagnetic equator. This reduces with increasing latitude, disappearing over the geomagnetic

poles.

Death from cancer is the principle health concern associated with occupational exposure to

radiation.

ICAO Annex 6, Part I Radiation Monitoring

All aeroplanes intended to be operated above 49,000ft shall carry equipment to measure and

indicate continuously the dose of total cosmic radiation being received and the cumulative dose on

each flight. The display unit shall be readily visible to a flight crew member.

Ozone

Is classified as a highly toxic gas and excessive levels can significantly impact respiratory functions.

Stratospheric ozone is found in varying quantities (peak: 115,000ft, negligible: 40,000ft).

Sensory Systems

Cognition:Attention, perception, memory, reasoning, judgement, imagining, thinking, speech.

Central Nervous System (CNS)

Takes care of the reception of stimuli, the transmission of nerve impulses and the activation of

muscle mechanisms. The conducting elements of the CNS are neurones (can be slow/generalised or

highly efficient/rapid).

There exists a sensory threshold, below which stimuli may not be detected by receptors even when

within the detectable frequency range.Habituation:If the stimulus is continuous/repetitive the receptor may change in sensitivity (displays

a diminishing response to that stimulus). Can have flight safety implications e.g. reduced visual

sensitivity due to an unchanging visual scene at high altitude.

Peripheral Nervous System (PNS)

Controls vital functions over which the individual has no conscious control (respiration, circulation,

intestinal movement, sweating). Also controls reactions to painful stimuli (reflexes).

Connects CNS to the rest of the body: - Sensory (provides input from body to CNS).

- Motor (carries signals to muscles and glands).

Somatic Nervous System

Includes all nerves controlling muscular system/external sensory receptors.

Reflex arc is an automatic involuntary reaction to a stimulus.

Autonomic Nervous System

Consists of motor neurons that control internal organs (heart, intestine, bladder).

Sympathetic Nervous System:Fight or Flight.

Parasympathetic Nervous System:Relaxation to maintain homeostasis.

Homeostasis:Maintenance of metabolic equilibrium.

Brain

Receives information from the Central and Peripheral Nervous Systems. It then acts as control centre


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for vital activity. Biological control systems are neuro-hormonal processes.

Contains three distinct parts: - Cerebrum (two hemispheres forming largest part of the brain).

- Cerebellum (essential to the control of the human body).

- Brain Stem (all structures between the cerebrum and spinal cord).

Sensory Receptors

Mechanoreceptors:Hearing, balance, stretching (most adaptable = hair).

Photoreceptors:Light.

Chemoreceptors:Smell, taste (also internal sensors in digestive/circulatory systems).

Thermoreceptors:Temperature changes.

Electroreceptors:Electrical currents.

Orientation in Flight

Eyes:Both peripheral and central vision. Most important sense for orientation.

Inner Ear:Vestibular (semi-circular canals and otoliths).

Kinesthesis

A variety of sensory endings (mechanoreceptors) in the skin, joints, muscles and deeper supporting

structures are influenced by forces acting on the body.

Proprioceptive sense:Uses mechanoreceptors to provide spatial relationships between body parts.

Visual System

Flight crew rely more on sight than any other sense to orientate themselves in flight.

Contributing factors: - Depth perception (for safe landings).

- Visual acuity (to identify terrain features/obstacles in the flight path).

Anatomy/Physiology of the Eye

Cornea:The clear portion of the eye. Light from an object enters and 70% of refraction takes place.

Pupil:The black area of the eye. After light refracts through the cornea it passes through the pupil.

Iris:Coloured portion of the eye. Controls the diameter of the pupil/amount of light entering eye.

Lens:Located behind the pupil and focuses light onto the retina.

Ciliary Muscle:Alters the curvature of the lens changing the refraction of light entering the eye.

(Accommodation).

Retina:Composed of many photosensitive cells (rods/cones).

Visual Cortex:Part of the brain where information from the eyes is interpreted.


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Rod and Cone Cells

Rods: - Peripheral vision and most concentrated outside the foveal region.

- Achromatically sensitive to low intensity light and to movement.

- Used for night vision (greatest sensitivity after 30-45 minutes in darkness).

Cones: - Central vision most concentrated in the foveal region directly opposite the lens.

- Most sensitive to bright light and distinguish form and colour.

- Each cell contains one of three different pigments (absorptions): blue/green/yellow.

Visual Field

Eyes sensitivity is able to adapt to ambient levels of illumination. Dark adaptation takes several

minutes. Light adaptation occurs mostly within a few seconds (complete after 23 minutes).

The visual field is the locus of all points on a surface in front of and concentric with the stationary

eye from which a visual signal can be stimulated.

Acuity:The ability of the eye to see detail.

6/6 vision = you can see at 6m, what normal people can see at 6m.

Day blind spot:Area of Optic Disk. No photosensitive cells on the retinal nerves. Evident when the

eye is fixated centrally forward as an object is brought inside the visual field.

Night blind spot:Area of Fovea. Central area of the retina lacks rod cells. Dim lighted objects are

most noticed in peripheral vision. Deliberate use of eccentric vision is important for night flying.

Empty-field Myopia:Absence of visual stimulus (clear sky), muscles in eye relax preventing lens

focus. Hinders effective search and detection. Problem minimised by focusing on an object further

than 12 metres away (wing tip).

Scanning

It is not possible to voluntarily make a continuous scan of featureless space. A scanning technique

should employ regularly spaced eye movements (each covering an overlapping sector of 10).

At night the scan should be executed more slowly to enable peripheral vision to detect objects.

Sunlight and its Effects on the Eyes

Visible light consists of a small portion of the spectrum (380 nanometresviolet to 760 nanometres

red). Blue light is very energetic and long term exposure may cause cumulative damage to the

retina.

Prolonged exposure to UV wave lengths can also cause damage (absorbed by the lens). UV lightproduces a painful swelling with sensitivity to light (snow blindness) after prolonged exposure to


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high-intensity sunlight (e.g. reflected by snow, water or desert). UV burns do not produce

permanent damage and usually filtered by cockpit transparency.

Sunglasses

Coloured Filters:Permit different amounts of light of different wavelengths to pass.

Neutral Filters:Absorb approximately equal amounts of all wavelengths of light.

Polarising: Limited in usefulness. Pilots may see dark bands when sky scanning.

Neutral-grey lens with 15% transmission is most suitable for the level of brightness when flying.

Distance Estimation and Depth Perception

Distance can be estimated by using individual or a variety of cues. Pilots normally use subconscious

factors to determine distance.

Stereoscopic Vision:Focusing both eyes on a single object. Each eye sees the object at a slightly

different angle. The images are merged together producing a three-dimensional image.

Binocular Cues:Depend on the slightly different view each eye has on an object. Only of value when

the object is close enough to make a perceptible difference in the viewing angle of both eyes.

Geometric Perspective:An object appears to have a different shape when viewed at varying

distances and angles.

- Linear Perspective:Parallel lines (railroad tracks), tend to converge as distance increases.

- Apparent Foreshortening:Objects appear higher on the horizon than those closer.

Motion Parallax:The apparent, relative motion of stationary objects as an observer moves.

Nearmove fast/opposite the path of motion. FarMove slow in the direction of movement/fixed.

Known Size of Objects

The nearer an object to an observer, the larger its retinal image. By experience, the brain learns to

estimate the distance of familiar objects. To use this cue, the observer must know the actual size of

the object and have prior visual experience of it.

Interposition of Objects

Lights disappearing/flickering in the landing area should be treated as barriers and the flight path

adjusted accordingly.

Visual Deficiencies

Myopia (Near-sightedness)

Error in refraction whereby the lens of the eye does not focus an image directly on the retina.

Distant objects are not seen clearly; only nearby objects are in focus.Eyeball too long.


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Hypermetropia (Far-sightedness)

Error in refraction as in myopia. However, nearby objects are not seen clearly.Eyeball too short.

Astigmatism

Caused by unequal curvature if the cornea or lens. Is the inability to focus different meridianssimultaneously.

Presbyopia

Part of the aging process which causes the lens to harden. Individuals gradually lose the ability to

accommodate for and focus on nearby objects.

Retinal Rivalry

If one eye is viewing one image while the other eye is viewing another, there may be a problem in

total perception. The dominant eye will override the non-dominant eye image.

Radial Keratotomy

Surgical procedure that creates multiple radial incisions in the cornea to produce better visual acuity.

Glare sensitivity is the most common complication of the procedure.

Colour Blindness

Permanent condition that affects males more than females. Individuals who are colour blind are

usually unable to distinguish between red and green. (Anomaly: weakness, Anopia: blindness).

Hypoglycaemia

Low sugar levels may result in hunger pains, distraction, breakdown in habit patterns, shortened

attention span. Missing/postponing meals can cause low blood sugar levels.

Cataracts

Lens opacity and changes the lens refractive index producing blurred vision. Scattering of light may

lead to glare sensitivity. Risk factors; old age, positive family history, diabetes, smoking.

Glaucoma

Occurs mainly in middle-later life due to elevated intraocular blood pressure (due to blockage).

Symptoms; blurred vision, haloes around bright lights, pain, vomiting, circumcorneal redness.

Dry Eyes

Low relative humidity in aircraft can lead to drying of the eye surface. Dryness causes discomfort and

may expose the individual to infection.


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Flash Blindness (from lightning)

Protection: - Increase cockpit lighting to max intensity.

- Lower seats/ cockpit sun visors.

- Look in as much as possible.

Near Vision Correction

When only near-vision requires correcting, pilots should never use full-lens spectacles whilst flying

(requires frequent changes from near/distant vision). Half-moon spectacles MUST be used.

Near and Distant Vision Correction

When both are required, bifocal lenses are essential and pilots are advised to with an AME/optician

the shape and size most suitable for each segment.

Varifocal Lenses

Alternate to bifocal/multifocal lenses. There is no clear demarcation between upper distance vision

and near vision correction of the lower portion of the lens (gradual merging). Not generally advisedfor flying.

Spectacles Restrict Peripheral Vision

All spectacles restrict peripheral vision and thick frames should be avoided. Spectacle wearers have

to increase their head movements in scanning. Photosensitive lenses should not be used.

Contact Lenses

An ophthalmic report from an optician is required to confirm contact lenses will provide a

satisfactory field of vision and that they have been worn for 8hrs a day over 1 month. A pair of

ordinary spectacles should be carried at all times.

Visual Clues on Landing

1) Assessment of Glideslope: - Lights: VASIs/PAPIs.

- To fly 3 Approach must ensure angle between eye/impact point is

3 below horizon.

2) Maintaining Glideslope: - Visual texture flows away from the impact point = APP GOOD.

3) Ground Prox. Judgements: - Apparent speed of ground.

- Texture of surface.

- Size, relationship and clarity of objects.

Vestibular System

The inner ear contains the

vestibular system, which is the

motion and gravity detecting

sense organ. This system is

located in the temporal bone on

each side of the head.


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Otolith Organs

Sense changes in linear acceleration or gravity and located in the vestibule. Changes in head position

relative to the gravitational force cause the otolithic membrane to shift position on the macula. The

sensory hairs bend, signalling a change in head position. When the head is upright, a resting

frequency of nerve impulses is generated by the hair cells. When the head is tilted, the resting

frequency is altered. The body cannot distinguish between the inertial forces from linear

accelerations and force of gravity (forward acceleration can create illusion of backward tilt).

Semicircular Canals

Sense changes in angular accelerations (yaw, pitch, roll attitude). Are situated in 3 perpendicular

planes to each other and filled with fluid (endolymph). Initial torque from angular acceleration puts

the fluid in motion moving hair stimulating the vestibular nerve. No acceleration means the hair cells

are upright.

During a clockwise acceleration a counter-clockwise movement of fluid in the canal is created. The

hairs cells bend in the direction of fluid movement. The canal wall and body move in the opposite

direction. The brain interprets the hair movement to be a turn in the same direction as the canal

wall. If continued for several seconds the fluid motion no longer lags (hairs no longer bend) and

brain receives false information a turn has stopped. When the aircraft rotation stops, it may befalsely interpreted as body movement in the opposite direction.

Proprioceptive System

Reacts to sensations resulting from pressures on joints, muscles, and skin. Forces act upon the

seated crew member in flight. With training and experience, the crew member can easily distinguish

the most distinct movement of the aircraft by the pressures of the seat against the body.


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Illusions

A false impression/misconception with respect to actual conditions or reality.

Somatogyral (Vestibular)

Caused when angular acceleration stimulates the semicircular canals. Occur in IMC/marginal VMC.

Leans:Most common form of spatial disorientation. Occurs when a crew member fails to perceive

some angular motions (during a slow roll, crew member feels the aircraft is still straight and level).

Pilot should trust attitude indicator and lean body in the original direction of roll until sensation

leaves.

Graveyard Spin:Usually occurs in fixed-wing aircraft when entering a spin for several seconds.

Semicircular canals reach equilibrium (no motion perceived). When recovered from the spin the

sense is a spin in the opposite direction.

Graveyard Spiral:Observed loss of altitude during a co-ordinated constant-rate turn that ceases

stimulating the motion sensing system. Creates the illusion of being in a descent with wings level.

Coriolis Illusion:Most dangerous of all vestibular illusions causing overwhelming disorientation. Can

take place whenever a climbing/descending turn is initiated. When making a head movement in a

geometrical plane other than that of the turn creates the feeling the aircraft is rolling, pitching and

yawing at the same time.

Vertigo

The illusion of movement (often rotary), of the individual or of their surroundings.

Causes:Disorders of the vestibular system, accelerations during steep turns (no horizon).

Symptoms:Difficulty in walking/standing, nausea, vomiting, pallor and sweating.

Alternobaric (Pressure) Vertigo

Causes:Blockage of the Eustachian tube. Can occur during ascent or descent.

Symptoms:Blurring of vision, apparent movement of the visual scene. Short-lived (10-15 seconds).

Most likely experienced when flying with a cold/similar infection.

Flicker Vertigo

Causes:Flashing light from flickering sunlight on rotor/propeller blades. Strobe light cloud reflection.

Symptoms:Irritation/distraction, disorientation of angular motion in opposite direction of shadow.

Wearing sunglasses or removing the individual from the lit area may relieve symptoms.

Somatogravic

Caused from changes in linear acceleration/gravity that stimulate the otolith organs.Oculogravic Illusion:Occurs when an aircraft accelerates forward. Causes a sense of a nose-high

attitude. Does not occur if adequate outside references are available. Cross-check instruments.

Elevator Illusion:Occurs during upward acceleration. Due to inertia, the pilots eyes track

downwards, causing a sense of aircraft nose rising. Common when encountering updraughts.

Oculoagravic Illusion:Exact opposite of Elevator illusion resulting from downward motion.

Proprioceptive Illusions

Rarely occur alone. Closely associated to the vestibular and visual systems. Proprioceptive inputs to

the brain may lead to a false perception of the true vertical.


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Prevention of Spatial Disorientation

- Never fly without visual reference points (natural or artificial horizon).

- Trust your instruments.

- Never stare at lights.

- Allow eyes to adapt to the dark before night flying.

- Avoid fatigue, smoking, hypoglycaemia, hypoxia, and anxiety (aggravates illusions).

Treatment of Spatial Disorientation

- Refer to instruments and develop a good cross-check.

- Never try to fly VMC and IMC at the same time.

- Delay intuitive actions long enough to check both visual and instrument references.

- Transfer control to the other crew member (if two crew).

Visual Illusions on Approach

Runway SlopeUpslope Think TOO HIGH

Downslope Think TOO LOW

Terrain Slope

Up to Runway Think TOO HIGH

Down to Runway Think TOO LOW

Lights

If Bright Think CLOSE TO RUNWAY

If Dim Think FAR AWAY FROM RUNWAY

Runway Width

If Wide Think TOO LOW

If Narrow Think TOO HIGH

Shallow Fog Layer Think PITCH UP

Black hole Approach

Occurs when approaching a runway on a dark night where the only lights visible are runway lights.

Tendency to think you are higher than you are resulting in a fly-down urge. ILS, VSI, VSIs/PAPIs can

assist in reducing this tendency. Can also occur in white-out conditions (light carries depth

perception messages to the brain in the form of; colour, glare, shadows).

Atmospheric Illusions

Rain on Windscreen Illusion of greater height

Atmospheric Haze Illusion of greater distance from runway

Fog Penetration Illusion of pitch up

False Horizon

A sloping cloud formation, an obscured dark horizon spread with ground lights and stars, and certain

geometric patterns of ground light. Can create the illusion of not being aligned with the horizon.


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Autokinesis

A distant light (star/aircraft tail-light) seen in the dark will appear to move about when stared at for

a time. Apparent movement increases if the light source becomes the prime focus of attention.

To avoid effects, shift gaze so as not to stare at a single light source.

Motion Sickness

Motion sickness is caused by continued stimulation of the inner ear. The symptoms are progressive.

First, the desire for food is lost. Then saliva collects in the mouth and the person begins to perspire

freely. Eventually, the person becomes nauseated and disorientated. The head aches and there may

be a tendency to vomit. If the air sickness becomes severe enough, the crew member may become

completely incapacitated.

Prevention of Motion Sickness

- Susceptible individuals should not take the preventative drugs (cause drowsiness).

- Open up air vents and loosen clothing.

- Use supplemental oxygen.

- Keep the eyes on a point outside the aircraft and avoid unnecessary head movements.

Acceleration

The rate of change of velocity and occurs when the speed or direction of a body changes. The

magnitude (G) of acceleration is expressed in multiples of the acceleration due to gravity (weight).

The bodys capacity to tolerate G depends on the intensity, duration and direction.

Long Duration (+1 second)

Headwards (+Gz) - Reduction of hydrostatic blood pressure above the heart, increase below.

+2.5Gz (loss of mobilitydifficult to stand up).+3.5Gz (loss of peripheral vision & loss of colour vision grey out).

+4.5Gz (black out hearing and mental functions unaffected at onset).

>+4.5Gz (unconsciousness G-LOC).

Footwards (-Gz) - More uncomfortable/dangerous than +Gz.

- Inertial forces increase vascular pressure in the upper thorax, head, neck.

- Symptoms: bursting of small vessels (eyes), pushing up of lower eyelid.

-3Gz (maximum tolerable levelfor short periods).

Short Duration (-1 second)

Mainly due to impact following a crash. Can withstand maximums of +45Gx and +25Gz.

Noise

The human range of hearing is 20 to 20,000Hz (most sensitive 200 to 6,800Hz).

Sound Measurement

Frequency:Physical characteristic that gives sound the quality of pitch. The number of oscillations or

cycles per second is measured in hertz.

Intensity:A measure that correlates sound pressure to volume. Measured in decibels (dB) which

express the relative intensity of sounds on a scale from zero to about 140. For every 20dB increase in

volume, sound pressure increases by a factor of 10.

Duration:The length of time an individual is exposed to a noise.


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Steady-state Noise:Continuous noise encountered around aircraft. High intensity (wide frequency).

Direct link between duration of exposure and intensity (louder sound = shorter time hearing loss).

Impulse Noise:Characterised by an explosive sound (high intensity). Most detrimental although

short duration (intensity usually exceeds 140dB).

Outer Ear: - Auricle (picks up sound waves) External canal Ear drum.

Middle Ear: - Ossicles (3 small bones) transfers sound waves from ear drum to inner ear.

Inner Ear: - Cochlea (composed of fluid-filled chambers with hair-like receptors).

Converts vibration to nerve impulses but loud noise may fatigue hair cells.

Hearing Loss

Conductive

Occurs when there is a defect/impediment of sound transmission from external to inner ear. Effects

al frequencies and can be treated medically (hearing aid)inner ear still capable of sound detection.

Sensorineural

Occurs when the hair cells of the cochlea are damaged. Most frequently produced by noise exposure

(NIHL) be can be caused by disease/aging. Occurs first in the higher frequencies. No known medical

treatment.

Presbycusis

Hearing loss caused by aging. Can be conductive or sensorineural in nature (or both).

Noise Exposure Criteria

Frequency:Narrow-bands/pure-tone more damaging (turbine engine whine).

Intensity:Louder = greater possibility of damage. >85dB can damage hearing.

Duration:For every 5dB increase above 85dB, safe time limit for exposure is reduced by half.

Vibration

Symptoms are determined by resonance effects according to frequency and amplitude of vibration.

14Hz Interference with breathing

410Hz Chest/Abdominal pains

812 Hz Backache

1020Hz Headaches, eyestrain, throat pains, speech disturbance, fatigue

2540Hz Visual impairment (skull resonance)

6090Hz Visual impairment (eyeball resonance)


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Sudden or Gradual Hearing Damage

Acoustic Trauma

Usually sudden resulting from intense impulse noise (+140dB). Most damage results in eardrum

injury. Repeated exposure damages the cochlea. Often manifested as a ringing sensation in ear.

Noise-induced Hearing Loss (NIHL)

Onset is much slower than acoustic trauma. Results from repeated exposure to steady-state noise

(such as that experienced at airports/in aircraft). Individuals rarely notice NIHL as it does not initially

affect the speech frequency range. A more subtle effect is the change in phonetic content of speech

(mumbling), only vowels (lower frequencies are heard). Early stages, communication difficult with

background noise. Later stages, speech recognition impossible.

Temporary Threshold Shift (TTS)

Temporary loss of hearing from overexposure to noise. Results from exposure for a short period of

time to intense noise levels (>78-84dB). NIHL occurs first as TTS (fatigue of cochlea cells). TTS canbecome permanent. 85dB is regarded as the max permissible sound level for continuous exposure to

steady-state noise.

TTS may last from a few minutes/hours to days (depending on duration/intensity of exposure).

Individuals mostly recover to near-normal hearing limits unless overexposed.

Permanent Threshold Shift (PTS)

Hearing loss present when the nerve fibres of the cochlea are destroyed (hair cell destruction is

permanent). May develop before an individual recognises that it is happening.

Hearing Protection

Crew members and ground-crew should wear hearing protection at all times. Virtually all NIHL is

preventable if these devices fit properly and are worn on all flights.

Protective measures include: - Designing quiet aircraft

- Enclosing the cabin areas with soundproofing

Earplugs:Most common type of protection. Have a tendency to work loose. Protection: 30-35dB.

Earmuffs:Tend to give slightly more high-frequency protection (less low) than earplugs.

Headsets:Provide some protection against high-frequency sound. Need to be properly maintained.

Decibels Effect on Listeners

0 Threshold of hearing

65 Average male conversation

85 Damage risk noise limit

90 Speech interference at 1ft

120 Threshold of discomfort

140 Threshold of pain

160 Eardrum rupture


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Drugs and Self Medication

Drugs Considered Incompatible with Flying

Antibiotics:May have short-term/delayed side effects. Indication implies an infection is present.

Antidepressants/Sedatives:Degrade a pilots ability to react.Stimulants:May cause dangerous overconfidence, headaches and dizziness.

Antihistamines:Widely available to allergy sufferers. Drowsiness is a common side effect.

Antihypertensives:Treat high blood pressure. Can change cardiovascular reflex and impair intellect.

Anaesthetics:Time elapse before flight: Local12 hours. General48 hours.

Analgesics:May significantly degrade a pilots performance. Indication implies significant pain.

Alcohol

Hypnotic drug which degrades a crew members judgement and ability to perform skilled tasks.

Consumption measured in units (1 unit = a standard glass of wine/half a pint of beer).

Maximum blood alcohol limit for pilots of 20 milligrams per 100 millilitres.Pilots are advised not to fly for at least 8 hours after ingesting small amounts of alcohol.

Alcohol wears off at a rate of approximately 1 unit (15mg per 100ml) per hour.

Damaging alcohol consumption levels: - Men: 6 units/day or 30 units/week.

- Women: 4 units/day or 20 units/week.

Nicotine/Tobacco

Nicotine is a highly addictive drug. Smoking tobacco is a major risk factor in lung cancer and

cardiovascular disease. Smoking exacerbates hypoxia. Reduces tolerance to G-forces and degrades

night vision.

Caffeine

Weak stimulant found in tea, coffee, soft drinks and some pain relieving medications. May cause

headaches in excessive doses.

Donors

Blood:Pilots should not fly within 24 hours.

Bone Marrow:Pilots should not fly within 48 hours.

Obesity

A weight to height ratio that exceeds a prescribed value. May be precipitated by genetic and

physiological factors (rarely by disease). Will reduce the bodys tolerances to G-forces, hypoxia and

decompression sickness.

Diabetes

Very common metabolic disorder that changes the way a body breaks down sugars (glucose) and

starches. Insulin helps to change glucose into energy that can be stored or instantly used.

Non-insulin-dependent:Pancreas produces insulin but body unable to use it effectively.

Insulin-dependent:Less common. Insulin injections given because of lack of insulin production.

Coronary Problems

Obesity contributes to congestive heart failure. Can also increase cholesterol, blood sugar levels andblood pressure.


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Gout

Genetic disorder in which the body produces an excessive amount of uric acid or the kidneys are

unable to eliminate the uric acid. The accumulating uric acid deposits in tissues and joints causing

inflammation, swelling and severe pain (gouty arthritis).

Arthritis

Inflammation and stiffening of the joints often causing great pain. Is a lifelong illness that can

progressively disable and handicap an individual. Extra weight from obesity puts extra stress on

joints.

Body Mass Index (BMI)eiht (k)

Heiht (m)

Underweight 30

Diet

Carbohydrates:Absorbed rapidly, chief and most important energy source for the body.

Fats:Provide most concentrated source of heat energy, can be stored in large quantities.

Proteins:Needed for building/repair of body tissues, composed of smaller units (amino acids).

Fibre:Complex mixture of indigestible plant substances. Essential for digestive/bowel process.

Tropical Diseases

Diseases/conditions similar to, prevalent or commonly encountered in areas characterised by aclimate with high temperature and humidity usually located within a region between the

North/South 23rd

degree parallels of latitude.

Water

Contaminated drinking water is one of the most frequent sources of intestinal infection. Unless one

is assured that centrally distributed water is constantly safe, it should not be used for human

consumption, for ice cubes or brushing teeth unless it has been purified.

Safest purification procedure is to boil water for 35 minutes and thereafter keep it in the same

vessel until used. If unable to boil, treat with a chlorination tablet.

Food

There is an old tropical food maxim not to eat raw any fruit or vegetable that does not have an

unbroken skin, and which has not been well washed and peeled/skinned by oneself immediately

prior to eating. Fruit salad should be avoided. In other cases, boiling/baking will render food safe.

Milk is safe only if boiled or as canned evaporated milk, condensed milk, or powdered milk (ice

cream is likely to be as contaminated as milk). Avoid cold pastries, custard, soft-type cheese and

other delicacies.

Food poisoning does occasionally occur on board aircraft or during flight. It is recommended that

crew members should not consume food from the same source prior to or during flight.


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Diarrhoea of Undetermined riin (ravellers Diarrhoea)

Acute diarrhoea onset characterised by frequent watery stools, acute gastro-enteritis, nausea,

vomiting, abdominal cramps, chills, myalgia and profound malaise. Rapid dehydration may occur.

May occur sporadically or in groups of travellers of all ages. Origin mostly not clearly established.

Cholera

Acute enteric infection caused by Vibrio Cholera.

Causes:Spread by the ingestion of water/foods contaminated by excrement of infected persons.

Prevention:Main method of control by purification of water supplies, proper disposal of excrement

and effective quarantine methods. Cholera vaccine provides varying degrees of protection for 6

months. Modern treatment greatly reduces mortality (untreated exceeds 50%).

Amoebic Dysentery (Amoebiasis)

May be encountered anywhere in the world.

Causes:Cysts from faeces of infected persons (transmitted: hand-mouth, polluted water, flies).

Symptoms:Liver, lung and brain abscesses (long latent period).

Malaria

Spread by mosquitos. Incubation period 89 days.

Symptoms:Chills, fever, sweating, intra-erythrocytic parasites, splenomegaly.

Prevention:Prophylactics, using anti-mosquito sprays/creams, wearing long sleeves.

Immunisations

Immunisation of flight crew differs according to country. The only worldwide compulsory

immunisation is against smallpox.

Toxic Materials

Aviation Gasoline (AVGAS)

AVGAS fumes are an upper respiratory irritant and produce tearing, choking, coughing and excess

salivation. It may also cause CNS hyperactivity, confusion, seizure or death. It can also cause

chemical skin burns.

Jet Fuels (AVTUR)

If inhaled in high concentrations, they may cause headaches, nausea, confusion, drowsiness,

convulsions, coma, and finally death. Prolonged skin exposure can lead to second degree burns.

Ethylene Glycol (Anitfreeze/Hydraulic Fluid)

Not an inhalation hazard unless heated. In cases of fatal poisonings, symptoms include those of

typical alcohol intoxication followed by coma and death.

Methyl Alcohol (De-icing Fluid)

Absorbed by ingestion producing disturbances of vision, headaches, vertigo, unsteady gait,

weakness, nausea and vomiting. Blindness is a common symptom.

Chlorobromo Methane (CBM)

Used in fire extinguishers to remove the oxygen from combustion. Considered safe for crew

members due to rapid dissipation and distance from extinguisher (engine).


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Halon

Gas is a CNS depressant which can lead to cardiac arrhythmia but is harmless if breathed for only a

few minutes.

Incapacitation

Most are caused by gastrointestinal upsets.

Obvious Incapacitation

Those immediately apparent to the remaining crew members. They can occur suddenly and are

usually prolonged resulting in a complete loss of function. It may be silent and occur without any

warning. Detection may only be indirect (not taking anticipated action).

Insidious Incapacitation

Can be harder to identify and more subtle in its onset (therefore more dangerous). Can be an even

greater problem when a drug will be used over a period of several days or longer.

Incapacitation Detection

Flight crew members should have a high index of suspicion of a subtle incapacitation any time a

crew member does not respond appropriately to two verbal communications.

A basic monitoring requirement is that all crew must know what should be happening with and to

the aircraft at all times (following SOPs).

Information Processing and Memory

Perception

The process of information extraction from the environment through experiences and sensed by the

five senses. The information is passed to the brain and interpreted, then memorised.

Bottom-up Processing:Uses sensory information to start building a mental model.

Top-down Processing:Uses previous knowledge to modify the mental model.

Physiological Sensing Errors

Caused by medical deficiencies (impaired vision/hearing) or hypoxia which reduces body oxygen

levels.

Complacency

Not paying attention or not using the senses properly is a problem during routine operations. Typical

problem for experienced crew members.

Processing Errors

Crew can also experience errors during the processing of the information in the brain. Previous

experience with the information enables processing to be much easier.

Pre-determined Opinions

Receiving information that we have a pre-determined opinion about (tendency to see/hear what we

expect). Microphone clipping, speaking too quietly and fast, background noise enhances the risk.


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Memory

The final part of the sensing and processing sequence. Selective attention requires information to be

stored in the sensory register. The working memory governs the information storing process.

Ultra-short Term: - Sensory register retains all sensory impressions up to about 1 second.

- Material is processed very quickly according to current importance.

-Iconic(stores visually 0.5 seconds) Echoic(stores auditory 8 seconds).

Short Term: - Working memory (focus of consciousness) holds material for20 seconds.

- Capacity is limited - maximum items for rehearsal is 7 (2).

Long Term: - Semantic:Based upon facts/skills. Info successfully entered is never lost.

- Episodic:Based upon memories/experiences, can be influenced.

- Procedural:Based upon motor memory, performed automatically.

Situational Awareness

Maintaining an accurate mental model of knowing: - Where the aircraft is.

- Where it has been.

- Where it is going.

Gestalt PsychologyA system of thought that regards all mental phenomena as being arranged in patterns/structures

(gestalts) perceived as a whole and not merely as the sum of their parts.

Gestalt Laws

Perception:Elements that are closer together tend to be seen as a group as do similar elements.

Organisation:Distinction between what is seen as the figure/object and what is seen as background.


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Stress

A heightened state of arousal caused by stressors (events that induces stress) in the environment.

In moderation, it is a key factor in the achievement of peak performance.

Too much= Loss of ability to reason/function. Too little= Complacency.

Types of Stress

Physical:Environmental conditions, noise, vibration, stages of hypoxia.

Physiological:Fatigue, lack of physical fitness, improper eating habits.

Emotional:Related to social and intellectual activities.

Categories of Stress

Chronic:Result of long term demands of lifestyle or personal situations (health, relationships, job).

Most dangerous, can exaggerate effects of acute stress. Can threaten health.

Acute:Result of demands placed on the body by a current issue (time constraints, bad weather).

Adrenaline enters bloodstream, body is charged into a fight or flight mode.

Effects of Stress: - Eroded judgement.

- Compromised or accepting of lower performance levels.

- Loss of vigilance and alertness.

- Loss of situational awareness.

Stress Coping Strategies

Coping is the process in which the individual either adjusts to the perceived demands of a situation

or changes the situation itself.

Action:Used to reduce the stress by removing the problem/altering situation.

Cognitive:Used when situation cannot be changed. Rationalisation/detachment from situation.System Direct:Removing stress symptoms with stress management (relaxation, counselling).

Fatigue

Considered to be one of the most treacherous hazards to flight safety. Crew members routinely

experience fatigue throughout their aviation careers.

The Danger of Fatigue

Individuals cannot readily feel the onset of fatigue (insidious) and may not be aware of its gradual

and cumulative effects (performance degradation).

Short Term (Acute):Normal in everyday life (tiredness after long periods of physical/mental strain).

Prevented by adequate rest/sleep, regular exercise and proper nutrition.

Long Term (Chronic):Not enough time for full recovery between episodes of acute fatigue.

Recovery requires a prolonged period of rest.

Causes of Fatigue: - Disturbance of circadian rhythms.

- Continuous wakefulness.

- Cumulative sleep loss.

Symptoms of Fatigue: - Slowed reaction time (physically and mentally).

- Increased errors despite increases effort.- Underestimation of performance degradation.


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- Impaired judgement and decision making.

- Fixation on a single source of information.

Stages of Sleep

Determined from: - Electroencephalogram (EEG) measuring brain activity.

- Electrooculogram (EOG) measuring eye movement.

- Electromyogram (EMG) measuring chin muscle activity.

When awake, the EEG shows two activity patterns: - Alpha (Resting)

- Bravo (Alert)

Stage 1: - 10 minutes long

- Transitional stage between waking and sleeping.

- Alpha small, rapid irregular waves. EOG = rolling eye movements.

Stages 24: - Stage 2 = 15 minutes (50% of sleep). Stage 3 = 15 minutes. Stage 4 = Early in night.

- Delta activity within deeper sleep stages (3 & 4)larger amounts.

- Stages 3 & 4 = slow wave sleep.

Rapid Eye Movement (REM) - Begins after 90 minutes.

- Then in 90 minute cycles (REM increases). Typically 45 cycles.

- EEG irregular, EOG rapid eye movements, EMG silent (relaxed).

Non-REM (Orthodox) Sleep:Revitalises the body after physical activity.

REM (Paradoxical) Sleep:Restores the brain after mental activity.

Circadian rhythmsRhythms having a period of about a day are called circadian rhythms. When the body receives no

clues from the environment these rhythms free-run around 25 hours.

Core body temperature averages 36.9C with a circadian fluctuation of 0.3C and with the lowest

temperature occurring around 05:00. Peak performance occurs with rising or high body

temperature.

Zeitgebers:From the German time giver. Cues that serve to synchronise the internal biorhythms.

Sleep Cycles

1 hour of high quality sleep = 2 hours of activity.

Around 8 hours may be an upper limit to the number of sleep hours credit that can be accumulated.When credit is exhausted the individual becomes lethargic and will require further sleep. Sleep

deficit reduces performance and is cumulative.


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Microsleeps

Uncontrolled, spontaneous episodes of sleep that could last for seconds or minutes.

The chances of microsleep increase during night-time hours and relative to the number of hours

worked.

Sleep Disorders

Insomnia:Difficulty in falling asleep/frequent awakening.

Hypersomnia:Excessively long/deep sleep. Only awakened by vigorous stimulation.

Narcolepsy:Involuntary attacks of sleep lasting around 15 minutes at any time of day.

Jet Lag:Mismatch between body clock and actual times. Westbound flights easier than Eastbound.

Personality

Emphasis is placed on the value of maintaining a friendly, relaxed, and supportive tone in the cockpit

and aircraft cabin.

Behavioural StylesRelationship Orientated:First considerationFeelings of others (caring/nurturing style).

Task Orientated:First considerationTask completion (aggressive style of behaviour).

Assertive Behaviour

High relationship and task orientated: - To put into words positively and with conviction.

- To defend/insist on the recognition of ones own rights.

- To state to be true.

Body Language: General - Attentive listening, assured manner, communicating, caring, strong.

Voice - Firm, warm, well-modulated, relaxed.

Eyes - Open, frank, direct, eye contact without staring.Stance - Well-balanced, straight on, erect, relaxed.

Hands - Relaxed motions.

In the cockpit, you have the right to ensure that your life will not be compromised by any

action/inaction, miscommunication or misunderstanding. Assertive behaviour in the cockpit does

not challenge authority; it clarifies position, understanding or intent enhancing safe operation.

Attitudes

Anti-authority:Found in people who do not like anyone telling them what to do.

Impulsivity:Those who frequently feel the need to do something, anything, immediately.

Invulnerability:Many people feel that accidents happen to others but never to themselves.

Macho:Those who are always trying to prove that they are better than anyone else.

Resignation:Those who do not see themselves as making a great deal of difference.


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Interactive Style

G = Goal Orientated P = Person Orientated

Leadership

Not a one-way process since it requires both leader actions and effective crew responses/feedback.

A leaders behaviour is less effective without complementary follower behaviour.

Primary Functions: - Regulation of the flow of information.

- Directing and co-ordinating crew activities.

- Motivation of crew members.

- Decision making.

Effective Leadership CharacteristicsCompetence:Technical and piloting skills should be good to inspire confidence in the crew.

Communication:Clear and concise with good listening skills. Personal emotion kept out.

Decision Making:Based on the situation at that time. All information used to find solution.

Perseverance:Sticks to the task regardless. Always confident a solution can be found.

Emotional Stability:Self-control maintained, personal emotions never cloud decision making.

Enthusiasm:When the leader is committed then the follower will usually give their best.

Ethics:Highest standard of professional conduct is expected at all times.

Recognition:Acknowledgement is given to the help of others.

Sensitivity:Stress/fatigue recognised in self and others to ensure overload does not develop.


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Flexibility:Adaptation of styles to the problem must be possible. No 2 emergencies the same.

Humour:Well direct humour is an effective tool, badly directed can be hurtful.

Delegation

A good leader will bring out the best in their team through trust and delegation of certain duties. In

the cockpit, the Commander and crew should make their own mental plan and discuss the outcome

in order to reach the ultimate conclusion and reduce chances for error.

Delegation of duties should not be done to the level where the combined workload becomes too

high.

Rasmussens Skill-Rule-Knowledge Framework

Skill Based Behaviour:Performance governed by stored patterns of pre-programmed instructions

and motor programmes learnt by practice/repetition. May be executed without conscious thought.

Rule Based Behaviour:Deals with familiar problems for which solutions are governed by rules stored

in long-term memory/checklists/SOPs. Conscious decision must be made to apply them.

Knowledge Based Behaviour:Comes into play in novel situations for which actions must be planned

using conscious, analytical processes and stored knowledge. Errors arise from resource limitations.

Maslows Hierarchy of Needs

Groups

Synergy:The working together of two items to produce an effect greater than the sum of their

individual efforts.

Group Cohesion:Refers to the extent individual group members are attracted to each other and the

group as a whole. Important for group performance.

Group-think (Risky Shift):Occurs when a highly cohesive group striving for unanimity of opinion

rather than a realistic appraisal of the situation. Decision more risky than that made by individual.


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Flight Deck Leadership

A generally democratic approach to problems is desirable, provided: -

1. It is directed towards achieving the operational goal.

2. There is time.

In emergencies a more autocratic approach necessary (based upon good pre-planning).

Whatever styleit must be consistent.

Attention

Vigilance:The task of constantly monitoring without lapses in attention.

Hypovigilance: An extremely agitated state of panic/near panic.

Arousal

The preparedness for performing any task. A

certain level of arousal is a positive influence on

performance. An extremely aroused pilot willunderperform than an optimally aroused one.

- The Yerkes-Dodson curve

Situational Awareness

Knowing what is going on and being prepared for

the unexpected.

Maintaining an accurate mental model of

knowing: - Where the aircraft is.

- Where it has been.

- Where it is going.

SA Level 1: Monitor

Focus on a broad regionkeep the big picture.

Focus on a narrow regionpay attention to detail.

Focus on the right informationdo not get side-tracked or distracted.

SA Level 2: Evaluate

Using all sources of information you have available and then assessing them to give SA for the

current state.

SA Level 3: Anticipate

Ensures crew have the same awareness of a problem and can both work to the same goal. Playing

the what if game has an advantage in SA.

Guidance for Situational Awareness

- Do not make up mental model from first sets of information (gather as much evidence) before

decision making.

- Do not hurry.

- Try to structure information so that logical conclusions can be reached.

- When decision made, check back to see if it still fits the facts.


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- Situational Awareness Model

Sterile Cockpit

The purpose is to reduce self-induced distractions during typically high-risk, high-workload phases of

flight.

Communication

Information, thoughts and feelings are exchanged in a readily and clearly understood manner.

Any message starts with a sender. It is eventually received by the receiver. To be effective this

message must be sent and received with the minimum of change to its meaning.

To ensure it has been correctly received a check of understanding must be carried out.

The Message

Whenever possible, and especially during high workloads, use short common words. Short and

simple commands prevent misunderstandings. Keep it short, keep it simple.

The process of establishing trust, good working conditions and a pleasant atmosphere should be

initiated during the pre-flight briefing.

Good Transmitter Good Receiver

- Clear and easy to understand message. - Pays attention.

- Good timing of transmission. - Notifies if unable to pay attention.

- Challenging understanding/feedback. - Acknowledges receipt and understanding.

Listening

The active listener attends to the words and projects their mind into that of the speaker, so that they

can align their thoughts and feelings more closely to those of the speaker.


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Closed Questions (for short answers): - Restricts the range of possible responses.

- Useful in getting specific information quickly.

- Improper use can feel like an interrogation.

How long are your shifts?

Open Questions (for long answers): - Allows the person a lot of freedom of response.

- Useful for identifying attitudes and beliefs.

What do you think about the approach into Heathrow?

Probe Questions (for more information):- Ask the person to clarify or elaborate.

- Can be verbal or non-verbal.

Tell me more about that.

Paraphrasing:To show understanding and encouragement by putting the other persons

ideas/feelings into your own words.

Active Listening: - The genuine desire to understand another persons perception.- Listening and expressing understanding of what the other person said.

- Sensitivity to anothers thoughts and feelings.

Discipline on-board

It is the Commanders responsibility to maintain the necessary discipline. The Commander sets the

tone and working atmosphere. If not, crew discipline can deteriorate rapidly.

Metacommunication:Communication about communication itself.

Decision Making

Operational Pitfalls

Peer Pressure:Based upon emotional response to peers rather than objectively evaluating.

Mind Set:The inability to recognise and cope with changes in the situation that may not be planned.

Get-there-itis:Causes a fixation on the original goal combined with disregard for alternatives.

Duck-under:Tendency to try to maintain visual contact with terrain while avoiding contact with it.

Confirmation Bias:Tendency to stay with decision ignoring evidence suggesting it was wrong.

Decision Making Process

- Recognise or identify the problem.

- Gather the information to assess the situation.- The information required and where that information is located needs to be established.

- Identify and evaluate alternative solutions (risks, advantages, disadvantage)select optimum.

- Implement the decision.

- Review the consequences by use of feedback. Evaluation and revision may be necessary.

Reaction to Decision Making

- Fly the aircraft (do not lose SA of the basic flying/confirm who is PF).

- Never assume that you do not have time (remain calm, think first, then actkeep crew in loop).

- Identify the problem.

- Assess the situation using all resources.- Select and carry out the correct procedure (keep it simple).


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- Continue evaluating the situation.

- Inform the cabin crew (crucial for cabin preparation and evacuation).

- Inform the passengers (seriousness of problem/cockpit workload determines how to brief).

Judgement:The process of recognising and analysing all available information about

oneself/crew/aircraft/flying environment followed by the rational evaluation of alternatives to

implement a timely decision which maximises safety.

DODAR : DiagnosisOptionsDecideAssignReview

Human Error

A failure on the part of the human to perform a prescribed act (or the performance of a prohibited

act) within specified limits of accuracy, sequence or time, which could result in damage to

equipment and property or disruption of scheduled operations.

Attributed as the main cause factor in 65-75% of all aviation accidents.

Error CategoriesCommission:Those in which pilots carried out some element of their task incorrectly/not required.

Omission:Those in which the pilot neglected to carry out some ele

Documents

ATPL Human Performance & Limitations