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ATPL Human Factors study materials
ATPL Human Factors study resources

ATPL Human Factors practice questions

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Question 1Human Factors: Basic Concepts

In aviation human factors, which model describes the interaction between liveware, hardware, software and environment, with a further liveware element at the centre?

  1. The Maslow hierarchy
  2. The SHELL model Correct answer.
  3. The Swiss cheese model
  4. The Yerkes-Dodson curve

Explanation

The SHELL model represents the cockpit as interactions between Software, Hardware, Environment and Liveware, with the central Liveware being the human operator. It highlights that mismatches at the interfaces between these components are where error is most likely to arise, and it is widely used to structure human factors training.

Question 2Human Factors: Basic Concepts

A pilot's performance is best described by which statement about the relationship between arousal and task difficulty?

  1. Arousal has no measurable effect on psychomotor performance
  2. Performance rises indefinitely as arousal increases
  3. Simple tasks are performed best at a lower level of arousal than complex tasks
  4. Complex tasks are performed best at a lower level of arousal than simple tasks Correct answer.

Explanation

The Yerkes-Dodson principle states that performance peaks at an intermediate level of arousal, and that the optimum shifts with task difficulty. For demanding, complex tasks the optimum arousal is relatively low, while simple well-learned tasks tolerate higher arousal before performance degrades.

Question 3Human Factors: Basic Concepts

Which statement correctly distinguishes an error from a violation?

  1. Both terms describe unintended actions that fail to achieve the intended outcome
  2. A violation can only occur when a person lacks the skill to perform the task correctly
  3. An error is an unintended action or plan that fails, while a violation is a deliberate deviation from a rule or procedure Correct answer.
  4. An error is a deliberate breach of a rule, while a violation is an unintended slip

Explanation

Errors are unintentional: the action or the plan behind it does not achieve the intended goal. Violations are intentional acts in which a person knowingly departs from an established rule, procedure or regulation, often for reasons such as convenience or perceived efficiency.

Question 4Human Factors: Basic Concepts

A pilot who knows the correct procedure but omits a step while under time pressure, without intending to do so, has most likely committed which type of error?

  1. A knowledge-based mistake
  2. A decision-based violation
  3. A violation
  4. A skill-based slip Correct answer.

Explanation

A slip is an unintended execution error in which a correctly planned action is carried out incorrectly, typically in routine, highly practised tasks. Because the pilot knew the procedure and had no intention of deviating, the failure lies in execution rather than in planning or deliberate rule-breaking.

Question 5Human Factors: Basic Concepts

Which of the following is the best example of a latent failure in an aviation organisation?

  1. A maintenance schedule that provides inadequate time to complete checks properly Correct answer.
  2. A controller issues an incorrect clearance in the moment
  3. An engineer installs a component the wrong way round
  4. A pilot misreads an altimeter during a busy approach

Explanation

Latent failures are organisational or systemic conditions, such as unrealistic schedules, poor procedures or inadequate resourcing, that lie dormant until they combine with active failures. They are created by decisions made far from the operational front line and may remain hidden for a long time before contributing to an accident.

Question 6Human Factors: Basic Concepts

According to the 'dirty dozen' list used in aviation maintenance human factors, which item refers to the physical and mental tiredness that degrades performance?

  1. Complacency
  2. Pressure
  3. Fatigue Correct answer.
  4. Distraction

Explanation

Fatigue in the dirty dozen refers to the physical and mental exhaustion that reduces alertness, slows reactions and impairs judgement. It is distinguished from other listed items such as complacency, distraction and pressure, each of which describes a different source of human error in maintenance work.

Question 7Human Factors: Basic Concepts

A crew is exposed to a mild but sustained level of stress during a long duty period. Which outcome is most consistent with the accepted relationship between stress and performance?

  1. Performance declines immediately and does not recover
  2. Performance is unaffected provided the stress is mild
  3. Performance may initially improve but then declines as stress becomes prolonged Correct answer.
  4. Performance improves steadily as the stress continues

Explanation

Moderate stress can raise alertness and motivation, producing a short-term improvement in performance. However, when stress is prolonged or exceeds the optimum, resources are depleted and performance deteriorates, consistent with the inverted-U relationship between stress and performance.

Question 8Human Factors: Basic Concepts

Which statement best describes the concept of situational awareness in flight operations?

  1. The skill of prioritising tasks strictly by their duration
  2. The ability to perceive, understand and predict what is happening in the operational environment Correct answer.
  3. The tendency to maintain a stable personality profile under pressure
  4. The capacity to remember checklist items under high workload

Explanation

Situational awareness has three levels: perception of relevant elements, comprehension of their meaning, and projection of their future state. Loss of situational awareness typically occurs when one or more of these levels breaks down, particularly under high workload or when attention is narrowed.

Question 9Human Factors: Basic Concepts

An experienced captain relies on a habitual response instead of checking the actual configuration, and the aircraft is misconfigured for the phase of flight. Which error mechanism best explains this?

  1. A perceptual error caused by an unserviceable instrument
  2. A violation caused by deliberate risk-taking
  3. A knowledge-based mistake caused by missing information
  4. A skill-based slip caused by an inappropriate habit or schema capturing the action Correct answer.

Explanation

Highly practised actions are controlled by schemas that can be triggered by familiar cues, so a strong habit may capture behaviour even when the situation differs from the usual one. This is a skill-based error of the slip type, because the intention was correct but the executed action was not.

Question 10Human Factors: Basic Concepts

Which statement best explains why human factors training emphasises non-technical skills such as communication and leadership?

  1. Because technical knowledge is no longer relevant in modern aircraft
  2. Because leadership ability determines a pilot's licence category
  3. Because non-technical skills can replace the need for standard operating procedures
  4. Because most accidents involve breakdowns in interpersonal coordination rather than purely technical failure Correct answer.

Explanation

Accident analyses repeatedly show that failures of communication, coordination, workload management and decision-making contribute to a large proportion of occurrences. Training in non-technical skills therefore addresses the human contribution to safety that technical training alone cannot cover.

Question 11Basic Aviation Physiology and Health Maintenance

Atmospheric pressure at sea level in the International Standard Atmosphere is approximately:

  1. 840 hPa
  2. 1000 hPa
  3. 1013 hPa Correct answer.
  4. 760 hPa

Explanation

The International Standard Atmosphere fixes sea-level pressure at 1013.25 hPa, equivalent to 29.92 inHg. This value is the reference from which pressure altitude and altimeter settings are derived.

Question 12Basic Aviation Physiology and Health Maintenance

As altitude increases within the troposphere, the partial pressure of oxygen in the air:

  1. increases
  2. remains constant
  3. decreases Correct answer.
  4. varies with humidity only

Explanation

The percentage of oxygen stays near 21 percent, but total barometric pressure falls with altitude, so the partial pressure of oxygen falls in proportion. This reduced partial pressure is the fundamental cause of hypoxic hypoxia at altitude.

Question 13Basic Aviation Physiology and Health Maintenance

The time of useful consciousness at 35 000 feet for a pilot breathing ambient air is approximately:

  1. 10 to 15 seconds
  2. 5 to 10 minutes
  3. 30 to 60 seconds Correct answer.
  4. 2 to 3 minutes

Explanation

At around 35 000 feet useful consciousness is typically about 30 to 60 seconds, falling rapidly as altitude increases further. The time is short because alveolar oxygen partial pressure collapses once ambient pressure is very low.

Question 14Basic Aviation Physiology and Health Maintenance

Which symptom is most characteristic of hyperventilation in a pilot?

  1. Light-headedness and tingling of the extremities Correct answer.
  2. Slow deep breathing
  3. Rising carbon dioxide levels
  4. Cyanosis of the lips

Explanation

Hyperventilation washes out carbon dioxide, producing cerebral vasoconstriction and respiratory alkalosis. This causes dizziness, tingling in the fingers and around the mouth, and often a feeling of breathlessness.

Question 15Basic Aviation Physiology and Health Maintenance

A pilot suspects hypoxia during a flight. The correct immediate action is:

  1. use the oxygen mask and descend Correct answer.
  2. hold the breath and continue
  3. turn off the oxygen supply
  4. increase cabin altitude

Explanation

The treatment for hypoxia is to restore oxygen partial pressure by breathing 100 percent oxygen and descending to a lower altitude. Descending increases ambient pressure and thus the alveolar oxygen partial pressure.

Question 16Basic Aviation Physiology and Health Maintenance

Decompression sickness in aviation is caused primarily by:

  1. low blood sugar
  2. carbon monoxide binding to haemoglobin
  3. nitrogen bubbles forming in tissues and blood Correct answer.
  4. excess oxygen in the blood

Explanation

Rapid reduction in ambient pressure allows dissolved nitrogen to come out of solution and form bubbles in tissues and blood. These bubbles cause the joint pain, skin and neurological symptoms of decompression sickness.

Question 17Basic Aviation Physiology and Health Maintenance

The primary function of the middle ear in relation to pressure changes is to:

  1. equalise pressure across the eardrum via the Eustachian tube Correct answer.
  2. amplify sound only
  3. produce earwax
  4. detect body orientation

Explanation

The Eustachian tube connects the middle ear to the nasopharynx and allows air to pass so that pressure on both sides of the eardrum equalises. Failure of this equalisation during descent produces ear pain and barotitis.

Question 18Basic Aviation Physiology and Health Maintenance

A pilot with a bad cold is most at risk of which condition during descent?

  1. Decompression sickness
  2. Sinus and ear barotrauma Correct answer.
  3. Night myopia
  4. Hyperventilation

Explanation

A cold blocks the Eustachian tube and sinus ostia, preventing pressure equalisation during descent. The resulting pressure gradient can cause severe ear and sinus pain and even eardrum damage.

Question 19Basic Aviation Physiology and Health Maintenance

Carbon monoxide poisoning in aviation is dangerous mainly because:

  1. it lowers cabin pressure
  2. it causes immediate unconsciousness in all cases
  3. it binds to haemoglobin far more readily than oxygen Correct answer.
  4. it has a strong irritating smell

Explanation

Carbon monoxide binds to haemoglobin with an affinity many times greater than oxygen, reducing the blood's oxygen-carrying capacity. Because it is odourless and colourless, it can build up without warning from heater or exhaust leaks.

Question 20Basic Aviation Physiology and Health Maintenance

Which of the following is a common early sign of hypoxia in a pilot?

  1. Improved reaction time
  2. Sharpened colour vision
  3. Euphoria and impaired judgement Correct answer.
  4. Increased night vision

Explanation

Early hypoxia often produces a sense of well-being or euphoria along with impaired judgement, so the pilot may not recognise the danger. Visual changes such as loss of colour and night vision also occur, but deterioration rather than improvement is expected.

Question 21Basic Aviation Physiology and Health Maintenance

The main reason pressurised aircraft cabins are kept at a cabin altitude of around 6000 to 8000 feet is to:

  1. reduce fuel consumption
  2. maintain adequate oxygen partial pressure for the crew and passengers Correct answer.
  3. increase airframe structural life
  4. prevent engine icing

Explanation

Keeping the cabin at a moderate altitude preserves a safe alveolar oxygen partial pressure for normal people while limiting the pressure differential the structure must bear. Higher cabin altitudes would increase the risk of hypoxia.

Question 22Basic Aviation Physiology and Health Maintenance

Spatial disorientation occurs when:

  1. the pilot's perception of attitude conflicts with reality Correct answer.
  2. the altimeter fails
  3. the pilot has ear pain
  4. the compass swings during turns

Explanation

Spatial disorientation arises when the vestibular and visual senses give misleading information about the aircraft's attitude or motion. Without reliable visual references, illusions such as the leans or somatogravic effects can develop.

Question 23Basic Aviation Physiology and Health Maintenance

The semicircular canals of the inner ear primarily detect:

  1. sound frequency
  2. linear acceleration
  3. angular acceleration Correct answer.
  4. static head position relative to gravity

Explanation

The semicircular canals contain fluid that lags or leads during rotation, bending the cupulae and signalling angular acceleration. Linear acceleration and gravity are detected by the otolith organs, the utricle and saccule.

Question 24Basic Aviation Physiology and Health Maintenance

The somatogravic illusion is most likely to occur during:

  1. rapid acceleration during take-off in poor visibility Correct answer.
  2. parking on the apron
  3. a steady level cruise
  4. a slow descent in clear air

Explanation

Strong linear acceleration stimulates the otolith organs in a way the brain interprets as a pitch-up, so the pilot may push the nose down. This illusion is most dangerous during take-off or go-around in low visibility.

Question 25Basic Aviation Physiology and Health Maintenance

A pilot who has donated blood should normally wait before acting as a flight crew member because:

  1. blood donation causes permanent anaemia
  2. there is a temporary reduction in oxygen-carrying capacity and possible faintness Correct answer.
  3. blood donation alters the altimeter setting
  4. blood donation affects the ears

Explanation

Donating blood reduces haemoglobin and blood volume temporarily, which can impair exercise tolerance and cause dizziness. Most authorities require a waiting period, commonly 24 to 48 hours, before flying.

Question 26Basic Aviation Physiology and Health Maintenance

Which of the following best describes the effect of alcohol on a pilot's performance?

  1. It has no effect below the legal limit
  2. It increases tolerance to hypoxia
  3. It improves night vision
  4. It reduces judgement and reaction time and increases risk-taking Correct answer.

Explanation

Alcohol depresses the central nervous system, slowing reaction time and impairing judgement and coordination. It also increases susceptibility to hypoxia and can disrupt sleep quality even after the blood level has fallen.

Question 27Basic Aviation Physiology and Health Maintenance

The main physiological effect of smoking on altitude tolerance is that it:

  1. improves lung diffusion
  2. raises the threshold for decompression sickness
  3. increases haemoglobin saturation with oxygen
  4. reduces oxygen-carrying capacity by forming carboxyhaemoglobin Correct answer.

Explanation

Carbon monoxide in tobacco smoke binds haemoglobin and reduces the amount available to carry oxygen. Smokers therefore reach the equivalent of a higher cabin altitude and show hypoxia at lower altitudes than non-smokers.

Question 28Basic Aviation Physiology and Health Maintenance

Fatigue in flight crew is best managed by:

  1. ignoring it because it resolves in flight
  2. flying faster to shorten the flight
  3. increasing caffeine intake throughout the duty
  4. proper rest, sensible duty scheduling and controlled napping Correct answer.

Explanation

Fatigue is managed through adequate rest, sensible rostering and planned rest opportunities, including controlled napping where permitted. Caffeine can mask fatigue temporarily but does not restore performance.

Question 29Basic Aviation Physiology and Health Maintenance

Circadian rhythm disruption is most likely for a pilot who:

  1. flies short sectors within one time zone
  2. takes regular daytime exercise
  3. flies only daytime local sectors
  4. repeatedly crosses several time zones on night flights Correct answer.

Explanation

Crossing multiple time zones disrupts the internal body clock, and night flying adds further desynchronisation. Repeated exposure prevents full adaptation and leads to cumulative fatigue.

Question 30Basic Aviation Physiology and Health Maintenance

The primary hazard of ozone at high flight levels is that it:

  1. increases cabin pressure
  2. reduces engine efficiency
  3. is an irritant that can damage lung tissue Correct answer.
  4. improves cabin air quality

Explanation

Ozone concentrations peak near the tropopause and at high latitudes, and it is a strong respiratory irritant. Cabin ventilation systems and ozone converters limit exposure, but prolonged high-level flight can still produce symptoms.

Question 31Basic Aviation Physiology and Health Maintenance

Which of the following is the most appropriate first action if a pilot experiences ear pain during descent?

  1. Increase the rate of descent
  2. Swallow, yawn or use the Valsalva manoeuvre to equalise pressure Correct answer.
  3. Climb rapidly to the previous altitude
  4. Remove the headset

Explanation

Ear pain on descent usually indicates the Eustachian tube has failed to equalise. Swallowing, yawning or a gentle Valsalva manoeuvre helps open the tube; if these fail, levelling off or climbing slightly may relieve the pressure before a slower descent.

Question 32Basic Aviation Physiology and Health Maintenance

Hyperventilation and hypoxia can be difficult to distinguish in flight because:

  1. both raise carbon dioxide levels
  2. both cause cyanosis
  3. both cause chest pain only
  4. both can produce dizziness and altered vision Correct answer.

Explanation

Both hypoxia and hyperventilation can cause light-headedness, tingling, visual disturbance and confusion, so the pilot may misjudge the cause. A practical discriminator is that 100 percent oxygen improves hypoxia but not hyperventilation.

Question 33Basic Aviation Physiology and Health Maintenance

The purpose of the Valsalva manoeuvre in aviation is to:

  1. improve night vision
  2. equalise pressure in the middle ear during descent Correct answer.
  3. reduce the effects of carbon monoxide
  4. increase heart rate during flight

Explanation

The Valsalva manoeuvre raises nasopharyngeal pressure, forcing air through the Eustachian tube to equalise middle-ear pressure during descent. It should be performed gently to avoid excessive pressure or cardiovascular effects.

Question 34Basic Aviation Physiology and Health Maintenance

A pilot taking a sedating antihistamine should:

  1. not act as flight crew while affected Correct answer.
  2. double the dose to reduce effects
  3. fly only short sectors
  4. fly only at night

Explanation

Sedating antihistamines impair alertness and reaction time and are incompatible with flying. The pilot should not act as flight crew until the medication's effects have worn off, in line with the applicable medical rules.

Question 35Basic Aviation Physiology and Health Maintenance

Which statement about decompression sickness is correct?

  1. It is caused by low blood sugar
  2. Symptoms may appear several hours after the flight Correct answer.
  3. It only occurs at altitudes above 40 000 feet
  4. It is prevented by breathing pure oxygen before flight

Explanation

Decompression sickness symptoms can be delayed, appearing from minutes up to many hours after the pressure exposure. This is why diving and flying intervals and post-flight observation periods exist.

Question 36Basic Aviation Physiology and Health Maintenance

At what approximate altitude does the average healthy pilot first begin to notice the effects of hypoxia without supplemental oxygen?

  1. Around 10000 feet Correct answer.
  2. Around 18000 feet
  3. Around 25000 feet
  4. Around 5000 feet

Explanation

Healthy individuals generally show measurable impairment of night vision from about 5000 feet, but clear daytime deterioration in judgement and coordination typically becomes noticeable near 10000 feet cabin altitude. This is why supplemental oxygen is recommended above that level.

Question 37Basic Aviation Physiology and Health Maintenance

Which gas normally makes up the largest proportion of the air we breathe?

  1. Carbon dioxide
  2. Argon
  3. Oxygen
  4. Nitrogen Correct answer.

Explanation

Dry atmospheric air is about 78 percent nitrogen and about 21 percent oxygen, with small amounts of argon and other gases. Because nitrogen is inert for metabolism, the body's oxygen supply depends on the partial pressure of oxygen, not on total pressure alone.

Question 38Basic Aviation Physiology and Health Maintenance

The oxygen-carrying capability of blood depends mainly on which component?

  1. Platelets
  2. Plasma proteins
  3. White blood cells
  4. Red blood cells Correct answer.

Explanation

Almost all oxygen is transported bound to haemoglobin inside red blood cells, with only a small fraction dissolved in plasma. A reduction in red cell mass or haemoglobin therefore directly reduces oxygen delivery to tissues.

Question 39Basic Aviation Physiology and Health Maintenance

A pilot flying at 8000 feet cabin altitude has been breathing 100 percent oxygen through a mask. What happens to the oxygen saturation of the blood compared with breathing cabin air?

  1. It falls because oxygen is dry
  2. It rises towards normal sea-level values Correct answer.
  3. It stays exactly the same
  4. It becomes dangerously high

Explanation

Breathing pure oxygen at a cabin altitude of 8000 feet raises the alveolar partial pressure of oxygen close to sea-level values, so haemoglobin saturation returns towards normal. This is the basis for using supplemental oxygen to correct mild hypoxia.

Question 40Basic Aviation Physiology and Health Maintenance

Which symptom pattern most clearly suggests that a pilot is suffering from hyperventilation rather than hypoxia?

  1. Slow, shallow breathing with drowsiness
  2. Tingling in the hands and around the mouth Correct answer.
  3. Progressively deepening confusion and grey skin
  4. Cyanosis of the lips and fingertips

Explanation

Hyperventilation washes out carbon dioxide, producing tingling in the extremities and around the mouth, often with dizziness or cramps. Hypoxia instead tends to cause cyanosis, deteriorating judgement and eventually loss of consciousness.

Question 41Basic Aviation Physiology and Health Maintenance

A pressurised aircraft suffers a rapid loss of cabin pressure at high altitude. What is the most immediate threat to the crew?

  1. Hypoxia Correct answer.
  2. Barotrauma of the gut
  3. Frostbite
  4. Decompression sickness

Explanation

With a sudden loss of pressure the alveolar oxygen partial pressure falls almost instantly, so hypoxia is the fastest and most lethal hazard. Oxygen masks must be donned first; other effects such as decompression sickness develop far more slowly.

Question 42Basic Aviation Physiology and Health Maintenance

What is the main reason aircraft cabins are humidified poorly and pilots may notice dry eyes and throat on long flights?

  1. Cabin air is heated and its relative humidity falls very low Correct answer.
  2. Cabin air is deliberately deoxygenated
  3. Cabin pressure is higher than sea level
  4. Cabin air is filtered to remove all water vapour

Explanation

At high cabin altitude the outside air is extremely cold and holds little moisture; when it is compressed and heated for the cabin, relative humidity drops to very low values. This causes drying of mucous membranes and contributes to fatigue and discomfort on long sectors.

Question 43Basic Aviation Physiology and Health Maintenance

Which action best reduces the risk of middle-ear barotrauma during a descent with a blocked Eustachian tube?

  1. Increase cabin altitude temporarily
  2. Keep the mouth open and breathe rapidly
  3. Descend as rapidly as possible
  4. Use a decongestant spray before the flight and swallow during descent Correct answer.

Explanation

A decongestant reduces mucosal swelling so the Eustachian tube can equalise pressure, and swallowing or yawning helps open it during descent. If equalisation still fails, the descent should be slowed or stopped rather than forced.

Question 44Basic Aviation Physiology and Health Maintenance

Which statement about the effects of positive g on the body is correct?

  1. G tolerance is increased by fatigue and dehydration
  2. Blood is displaced towards the head and vision improves
  3. G tolerance is unaffected by anti-g straining
  4. Blood pools in the legs and reduces venous return to the heart Correct answer.

Explanation

Positive g forces blood away from the head towards the lower body, reducing venous return and cerebral perfusion, which can lead to grey-out and loss of consciousness. Anti-g suits and the straining manoeuvre help maintain blood pressure at the brain.

Question 45Basic Aviation Physiology and Health Maintenance

A pilot experiences visual grey-out during a high-g turn. Which immediate action is most appropriate?

  1. Perform the anti-g straining manoeuvre and reduce g load Correct answer.
  2. Relax the anti-g strain and look away
  3. Increase the rate of turn to finish quickly
  4. Hold the breath and pull harder

Explanation

Grey-out signals reduced blood flow to the retina and is a warning of impending g-induced loss of consciousness. The correct response is to strain against the g load and reduce the g level until vision recovers.

Question 46Basic Aviation Physiology and Health Maintenance

Which of the following best describes the effect of ageing on a pilot's susceptibility to hypoxia?

  1. Older pilots generally tolerate hypoxia better
  2. Ageing has no effect on hypoxia tolerance
  3. Ageing only affects night vision
  4. Older pilots generally show hypoxia effects at lower altitudes Correct answer.

Explanation

With age, lung function and cardiac output decline and the body's compensatory responses become less efficient, so hypoxia symptoms appear at lower cabin altitudes. This is one reason older pilots should use supplemental oxygen earlier.

Question 47Basic Aviation Physiology and Health Maintenance

A pilot reports feeling unwell with a fever and is considering flying. Which statement best reflects the physiological risk?

  1. Fever reduces oxygen demand and improves performance
  2. Fever only affects the ears and not the rest of the body
  3. Fever has no effect on judgement
  4. Fever increases oxygen demand and reduces tolerance to altitude Correct answer.

Explanation

Fever raises metabolic rate and oxygen consumption, so the body's reserve for coping with reduced oxygen at altitude is smaller. Combined with dehydration and fatigue, this makes incapacitation more likely during flight.

Question 48Basic Aviation Physiology and Health Maintenance

Which statement about the use of caffeine by aircrew is most accurate?

  1. Caffeine can improve short-term alertness but may disturb sleep Correct answer.
  2. Caffeine reverses the effects of alcohol
  3. Caffeine counteracts hypoxia at altitude
  4. Caffeine has no effect on sleep or alertness

Explanation

Caffeine is a stimulant that can temporarily improve vigilance, but taken late in the day it delays sleep onset and reduces sleep quality, which contributes to fatigue. It does not reverse alcohol impairment or protect against hypoxia.

Question 49Basic Aviation Physiology and Health Maintenance

What is the main physiological reason for the recommended rest period after scuba diving before flying?

  1. To allow the eyes to adapt to bright light
  2. To restore blood sugar levels
  3. To allow the ears to recover from water pressure
  4. To allow dissolved nitrogen to be eliminated from body tissues Correct answer.

Explanation

Diving exposes the body to increased pressure, causing extra nitrogen to dissolve in tissues. Flying soon afterwards lowers the ambient pressure and can precipitate decompression sickness, so a rest interval is required.

Question 50Basic Aviation Physiology and Health Maintenance

Which of the following is the most reliable way for a pilot to detect the onset of hypoxia before performance is seriously degraded?

  1. Use a pulse oximeter or attend altitude training Correct answer.
  2. Wait for a headache to develop
  3. Rely on subjective feelings of breathlessness
  4. Monitor the aircraft's cabin rate of climb

Explanation

Hypoxia impairs the very judgement needed to recognise it, so subjective feelings are unreliable. A pulse oximeter provides an objective saturation reading, and altitude chamber training helps pilots learn their own early symptoms.