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CPL Human Performance practice questions

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Question 1Basic Aviation Physiology and Health

At what approximate cabin pressure altitude does the body's oxygen saturation begin to fall significantly in a healthy pilot breathing air without supplemental oxygen?

  1. Around 5,000 feet
  2. Around 10,000 feet Correct answer.
  3. Around 25,000 feet
  4. Around 18,000 feet

Explanation

Healthy individuals generally maintain adequate oxygen saturation up to about 10,000 feet cabin altitude, above which the falling alveolar oxygen partial pressure starts to reduce saturation noticeably. This is why supplemental oxygen is typically required above that level.

Question 2Basic Aviation Physiology and Health

Which symptom is most characteristic of the early stage of hypoxic hypoxia in flight?

  1. Sharp chest pain radiating to the arm
  2. Sudden loss of hearing
  3. Severe joint pain
  4. Impaired judgment and a sense of well-being Correct answer.

Explanation

Early hypoxia typically produces euphoria, poor self-criticism and impaired judgment before the pilot notices any physical distress. Because the pilot's own judgment is affected, self-detection is unreliable and oxygen use must be disciplined.

Question 3Basic Aviation Physiology and Health

A pilot's pulse oximeter reads 90 percent at a cabin altitude of 8,000 feet. What is the most appropriate first action?

  1. Descend immediately to sea level as an emergency
  2. Increase supplemental oxygen flow and check the equipment Correct answer.
  3. Continue the flight and recheck in 30 minutes
  4. Ignore the reading because oximeters are unreliable in flight

Explanation

A saturation of 90 percent at 8,000 feet is below the expected value for a healthy pilot and warrants checking oxygen delivery and increasing flow. If saturation does not improve, descent becomes necessary.

Question 4Basic Aviation Physiology and Health

During a rapid decompression at 35,000 feet, roughly how long does a pilot have before time of useful consciousness is lost?

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

Explanation

The FAA training table gives approximately 15 to 30 seconds of useful consciousness after rapid decompression at 35,000 feet. This is an approximate interval for effective performance, not a precise deadline for every pilot; individual and situational variation makes immediate use of oxygen essential.

Question 5Basic Aviation Physiology and Health

What is the primary physiological danger of a rapid decompression at high altitude?

  1. Rapid cooling of the cabin only
  2. Increased cabin noise
  3. Immediate hypoxia combined with expanding gas in body cavities Correct answer.
  4. Loss of hydraulic pressure

Explanation

A rapid decompression exposes occupants to abrupt hypoxia and allows trapped gases to expand, risking barotrauma and, if severe, decompression sickness. Both effects demand immediate oxygen and emergency descent.

Question 6Basic Aviation Physiology and Health

A pilot performs a scuba dive to 30 feet and surfaces in the morning. What is the recommended minimum interval before flying to reduce decompression sickness risk?

  1. No interval is needed for a shallow dive
  2. 12 hours Correct answer.
  3. 24 hours
  4. 48 hours

Explanation

For dives that do not require decompression stops, a preflight interval of at least 12 hours is widely recommended, extending to 24 hours or more after decompression-stop dives. Residual nitrogen raises the risk of decompression sickness at cabin altitude.

Question 7Basic Aviation Physiology and Health

Which factor most increases a pilot's susceptibility to decompression sickness at cabin altitude?

  1. Good physical fitness
  2. Wearing a headset
  3. Recent diving, obesity and dehydration Correct answer.
  4. Flying at low cabin altitude

Explanation

Residual nitrogen from recent diving, body fat, dehydration and fatigue all increase the likelihood of bubble formation and decompression sickness. Fitness and hydration generally reduce risk.

Question 8Basic Aviation Physiology and Health

What is the most effective countermeasure against spatial disorientation during flight in poor visual conditions?

  1. Leaning the head toward the perceived horizon
  2. Trusting and cross-checking flight instruments Correct answer.
  3. Increasing head movement to gather more cues
  4. Relying on seat-of-the-pants sensations

Explanation

When outside visual references are unreliable, only instrument indications provide a trustworthy attitude reference. Pilots must be trained to interpret and cross-check instruments rather than trust vestibular sensations.

Question 9Basic Aviation Physiology and Health

A pilot in a sustained coordinated turn without outside visual reference feels a sensation of not turning. This is best described as which illusion?

  1. Somatogravic illusion
  2. Autokinetic illusion
  3. Coriolis illusion
  4. Leans illusion Correct answer.

Explanation

In a prolonged coordinated turn the semicircular canals adapt to the constant angular velocity and stop signalling the turn, producing the leans illusion on recovery. The pilot may mistakenly believe the aircraft is straight and level.

Question 10Basic Aviation Physiology and Health

During acceleration for takeoff in darkness, a pilot may feel as though the aircraft is pitching up steeply. Which illusion is this?

  1. Gravitational illusion
  2. Somatogravic illusion Correct answer.
  3. Oculogravic illusion
  4. Black hole approach illusion

Explanation

Linear acceleration stimulates the otolith organs much like a pitch-up, producing the somatogravic illusion. The pilot may push the nose down in response, which is dangerous close to the ground.

Question 11Basic Aviation Physiology and Health

Which measure best reduces the risk of the Coriolis illusion during instrument flight?

  1. Making large, rapid head movements to scan the panel
  2. Flying with the cabin lights off
  3. Turning off the attitude indicator
  4. Avoiding abrupt head movements during prolonged turns Correct answer.

Explanation

The Coriolis illusion is triggered by abrupt head movement while the aircraft is turning, so pilots should move the head slowly and deliberately. Smooth scanning technique reduces vestibular conflict.

Question 12Basic Aviation Physiology and Health

Which visual cue most strongly contributes to a false sensation of height on approach at night over water with few lights?

  1. Absence of ground reference causing a black hole approach Correct answer.
  2. Strong crosswind
  3. Bright runway lights ahead
  4. High cabin altitude

Explanation

A dark featureless area between the aircraft and the runway removes visual cues for height and glide path, producing the black hole approach illusion. Pilots tend to fly too low and should rely on instruments.

Question 13Basic Aviation Physiology and Health

Which statement correctly describes the effect of positive G on the cardiovascular system?

  1. Blood pools in the lower body, reducing cerebral blood flow Correct answer.
  2. Heart rate falls immediately to zero
  3. Blood is displaced toward the head, raising cerebral pressure
  4. Blood pressure in the brain rises sharply

Explanation

Positive G forces blood away from the head toward the legs, reducing venous return and cerebral perfusion, which can lead to greyout and eventually G-LOC. Countermeasures include the anti-G straining manoeuvre and G-suits.

Question 14Basic Aviation Physiology and Health

A pilot begins to experience tunnel vision and greying of the visual field during a high-G manoeuvre. What is the most appropriate immediate response?

  1. Increase the G load to finish the manoeuvre quickly
  2. Close the eyes until the sensation passes
  3. Relax the body and reduce the G load Correct answer.
  4. Hold the breath and remain tense

Explanation

Greyout signals reduced blood flow to the retina and is a warning of impending G-LOC. The pilot should reduce G, perform the anti-G straining manoeuvre and avoid further loading until symptoms resolve.

Question 15Basic Aviation Physiology and Health

What is the purpose of the anti-G straining manoeuvre?

  1. To increase blood pressure in the head by tensing muscles and controlled breathing Correct answer.
  2. To lower heart rate before takeoff
  3. To reduce oxygen consumption by breathing slowly
  4. To improve night vision

Explanation

The anti-G straining manoeuvre combines leg and abdominal muscle tensing with a cyclic breathing pattern to raise blood pressure and maintain cerebral perfusion under high G. It is a key non-equipment countermeasure.

Question 16Basic Aviation Physiology and Health

Which statement about negative G forces is correct?

  1. They have no physiological effect
  2. They push blood toward the feet
  3. They always improve vision
  4. They push blood toward the head and can cause redout Correct answer.

Explanation

Negative G drives blood toward the head, raising intracranial pressure and producing a redout sensation along with discomfort. It is generally less well tolerated than positive G.

Question 17Basic Aviation Physiology and Health

What is the most common cause of in-flight incapacitation among airline pilots?

  1. Cardiovascular events Correct answer.
  2. Food poisoning
  3. Gastrointestinal illness
  4. Ear infection

Explanation

Cardiovascular events, including sudden cardiac incapacitation, are the most significant cause of sudden in-flight incapacitation. This is why cardiovascular risk assessment is central to aeromedical certification.

Question 18Basic Aviation Physiology and Health

A pilot with a severe head cold and blocked eustachian tubes plans to fly. What is the main aeromedical concern?

  1. No concern at all
  2. Increased risk of barotrauma to the ears and sinuses Correct answer.
  3. Reduced oxygen consumption
  4. Improved equalisation during descent

Explanation

A blocked eustachian tube prevents pressure equalisation, risking severe ear pain, barotrauma and possible tympanic membrane damage, particularly during descent. Flying with a significant cold is therefore inadvisable.

Question 19Basic Aviation Physiology and Health

Which action is most appropriate to help equalise ear pressure during descent?

  1. Valsalva manoeuvre and swallowing Correct answer.
  2. Descending as rapidly as possible
  3. Holding the breath and straining against a closed glottis while asleep
  4. Increasing cabin altitude

Explanation

Swallowing, yawning and a gentle Valsalva manoeuvre open the eustachian tube and allow pressure equalisation during descent. Rapid descent without equalisation increases the risk of barotrauma.

Question 20Basic Aviation Physiology and Health

Which of the following best describes the effect of alcohol on pilot performance at altitude?

  1. It reduces the risk of decompression sickness
  2. It has no effect below 10,000 feet
  3. It impairs judgement and worsens hypoxia tolerance Correct answer.
  4. It improves reaction time

Explanation

Alcohol impairs judgement, coordination and reaction time, and it also increases susceptibility to hypoxia at altitude. Its effects can persist long after drinking, so a conservative bottle-to-throttle interval is required.

Question 21Basic Aviation Physiology and Health

A pilot is prescribed a sedating antihistamine for hay fever. What is the most appropriate course of action?

  1. Take a double dose to reduce symptoms faster
  2. Fly only at night
  3. Do not fly while affected and seek a non-sedating alternative Correct answer.
  4. Fly as normal because the medication is legal

Explanation

Sedating antihistamines impair alertness and reaction time and are incompatible with flying. The pilot should remain grounded while affected and consult an aviation medical examiner about a non-sedating alternative.

Question 22Basic Aviation Physiology and Health

Which statement best describes the effect of fatigue on pilot performance?

  1. It increases tolerance to hypoxia
  2. It improves situational awareness
  3. It slows reaction time and impairs judgement Correct answer.
  4. It has no effect on instrument scanning

Explanation

Fatigue degrades attention, slows reaction time and impairs judgement, and it also reduces tolerance to other stressors such as hypoxia. Fatigue risk management relies on adequate rest and duty limits.

Question 23Basic Aviation Physiology and Health

A pilot working a night shift pattern reports persistent difficulty sleeping and daytime sleepiness. Which concept best explains this?

  1. Circadian rhythm disruption Correct answer.
  2. Barotrauma
  3. Decompression sickness
  4. Hyperventilation

Explanation

Night shifts conflict with the body's circadian rhythm, causing sleep disruption and daytime sleepiness that impair performance. Managing light exposure and rest scheduling helps mitigate the effect.

Question 24Basic Aviation Physiology and Health

What is the primary physiological effect of hyperventilation on carbon dioxide levels in the blood?

  1. It raises carbon dioxide and causes acidosis
  2. It has no effect on blood gases
  3. It increases oxygen saturation to 100 percent permanently
  4. It lowers carbon dioxide and can cause dizziness and tingling Correct answer.

Explanation

Hyperventilation blows off carbon dioxide, producing hypocapnia with symptoms such as dizziness, tingling and cramping. It can mimic hypoxia, so oxygen and controlled breathing are used in response.

Question 25Basic Aviation Physiology and Health

A pilot breathing oxygen at high altitude notices a dry cough and chest discomfort. Which factor is most likely relevant?

  1. Barotrauma of the middle ear
  2. Coriolis illusion
  3. Oxygen toxicity from prolonged high-concentration exposure Correct answer.
  4. Decompression sickness

Explanation

Prolonged breathing of high-concentration oxygen, especially at high altitude, can cause pulmonary irritation and chest symptoms. Oxygen exposure must be managed according to altitude and duration.

Question 26Basic Aviation Physiology and Health

At what approximate cabin altitude does the partial pressure of oxygen in the blood begin to fall measurably in a healthy pilot breathing air without supplementary oxygen?

  1. Around 18,000 feet
  2. Around 10,000 feet Correct answer.
  3. Around 5,000 feet
  4. Around 25,000 feet

Explanation

Haemoglobin remains well saturated in healthy lungs up to roughly 10,000 feet cabin altitude, so oxygen saturation stays near normal below that level. Above about 10,000 feet the alveolar oxygen partial pressure falls enough that saturation declines progressively and night vision and judgement are affected first. The other values describe thresholds for more severe hypoxia or for breathing difficulties without oxygen.

Question 27Basic Aviation Physiology and Health

A pilot flying unpressurised at 14,000 feet notices tingling in the fingers, a feeling of warmth and a sense of unreality. Which condition best fits this picture?

  1. Hypoxia from reduced oxygen partial pressure Correct answer.
  2. Decompression sickness from dissolved nitrogen
  3. Hyperventilation caused by anxiety
  4. Carbon monoxide poisoning from cabin heating

Explanation

At 14,000 feet without supplementary oxygen the alveolar oxygen partial pressure is low enough to produce hypoxia, whose early signs include tingling, warmth, light-headedness and a false sense of well-being. These symptoms are classic for hypoxia at moderate altitude and resolve quickly with oxygen. The other conditions produce different or additional features and are less likely in this straightforward altitude exposure.

Question 28Basic Aviation Physiology and Health

Which statement best describes the time of useful consciousness for a pilot breathing air after a rapid decompression to 40,000 feet cabin altitude?

  1. About 15 to 20 seconds Correct answer.
  2. About 2 to 3 minutes
  3. About 10 to 15 minutes
  4. About 30 minutes

Explanation

At 40,000 feet the alveolar oxygen partial pressure falls so sharply that useful consciousness is lost in roughly 15 to 20 seconds, and the period may be even shorter during the decompression itself. This is why immediate use of oxygen after a rapid decompression at high altitude is critical. The longer times apply to lower cabin altitudes.

Question 29Basic Aviation Physiology and Health

A pilot is exposed to a cabin altitude of 8,000 feet for several hours. Which physiological change is most likely to occur?

  1. Increased urine output due to reduced ADH secretion
  2. Increased carbon dioxide retention in the blood
  3. Reduced heart rate at rest
  4. Mild respiratory alkalosis from increased ventilation Correct answer.

Explanation

At 8,000 feet the reduced oxygen partial pressure stimulates ventilation, which blows off carbon dioxide and tends to produce a mild respiratory alkalosis. The body compensates by renal excretion of bicarbonate over hours to days. Heart rate rises rather than falls, and carbon dioxide is lost rather than retained.

Question 30Basic Aviation Physiology and Health

Which statement about the effects of smoking on a pilot's oxygen carriage is correct?

  1. Carbon monoxide from smoking reduces the oxygen-carrying capacity of haemoglobin. Correct answer.
  2. Smoking has no measurable effect on oxygen saturation at altitude.
  3. Smoking only affects lung mechanics and not blood oxygen transport.
  4. Smoking increases haemoglobin's affinity for oxygen, improving altitude tolerance.

Explanation

Carbon monoxide binds haemoglobin with much greater affinity than oxygen, forming carboxyhaemoglobin that cannot carry oxygen and shifts the dissociation curve. A smoker therefore starts at altitude with a reduced effective oxygen capacity and reaches hypoxic symptoms at a lower cabin altitude. The effect is on blood transport, not merely lung mechanics.

Question 31Basic Aviation Physiology and Health

A pilot with a history of spontaneous pneumothorax wants to return to flying. Which consideration is most relevant to the aeromedical assessment?

  1. Whether the pilot can tolerate the noise of the cockpit
  2. Whether the pilot has completed a recent instrument rating
  3. The risk of recurrence at altitude and the need for a defined observation period Correct answer.
  4. The pilot's body mass index alone

Explanation

A previous pneumothorax carries a risk of recurrence, and a recurrence in flight could cause sudden incapacitation from chest pain and breathlessness. Aeromedical assessment therefore focuses on the interval since the event, the underlying cause and any surgical treatment such as pleurodesis. The other factors do not address the recurrence risk that matters for flight safety.

Question 32Basic Aviation Physiology and Health

Which of the following best explains why a pilot with a severe head cold should avoid flying?

  1. A cold increases the risk of decompression sickness.
  2. A cold raises the threshold for hypoxia.
  3. The cold virus reduces night vision.
  4. Swelling of the eustachian tubes impairs pressure equalisation and can cause barotrauma. Correct answer.

Explanation

A cold causes mucosal swelling that can block the eustachian tubes, so the pilot cannot equalise middle-ear pressure during climb or descent. This can lead to ear pain, haemorrhage or even rupture of the tympanic membrane. The other options do not reflect the main aeromedical concern.

Question 33Basic Aviation Physiology and Health

What is the most appropriate immediate action for a pilot who suspects hyperventilation during a stressful instrument approach?

  1. Hold the breath as long as possible to retain carbon dioxide.
  2. Slow the breathing rate and, if necessary, breathe into a bag or cupped hands. Correct answer.
  3. Descend rapidly to a lower altitude to increase oxygen.
  4. Increase the rate of deep breathing to improve oxygenation.

Explanation

Hyperventilation lowers carbon dioxide and causes tingling, dizziness and anxiety that can mimic hypoxia. Slowing the breathing and rebreathing exhaled air raises carbon dioxide back toward normal. Increasing ventilation or breath-holding can worsen the problem, and a rapid descent is not the primary treatment.

Question 34Basic Aviation Physiology and Health

Which statement correctly describes the relationship between alcohol and hypoxia at altitude?

  1. Alcohol improves alertness at altitude by reducing anxiety.
  2. Alcohol increases the oxygen-carrying capacity of the blood.
  3. Alcohol has no effect on altitude tolerance.
  4. Alcohol depresses respiration and worsens hypoxia while impairing judgement. Correct answer.

Explanation

Alcohol is a central nervous system depressant that impairs judgement and reaction time and can depress respiration, adding to the effects of hypoxia at altitude. Even small amounts can produce greater impairment in the air than at sea level. It does not improve alertness or oxygen carriage.

Question 35Basic Aviation Physiology and Health

A pilot taking a prescribed medication notices drowsiness and slowed reactions. Which principle should guide the decision to fly?

  1. Fly only on short sectors.
  2. Reduce the dose and fly if symptoms improve.
  3. Do not fly until the effects and the underlying condition are assessed by an aviation medical examiner. Correct answer.
  4. Fly only if the symptoms are mild.

Explanation

Any medication that causes drowsiness or slows reactions can impair flight safety, and the underlying condition may also be relevant. The pilot should not fly until an aviation medical examiner has assessed both the medication and the condition. Self-adjusting the dose or judging symptoms as mild is not an acceptable basis for flight.

Question 36Basic Aviation Physiology and Health

Which statement best describes the effect of fatigue on a pilot's performance?

  1. Fatigue improves concentration on routine tasks.
  2. Fatigue mainly reduces physical strength while leaving decision-making intact.
  3. Fatigue slows reaction time and impairs attention and judgement. Correct answer.
  4. Fatigue has no effect on instrument scan.

Explanation

Fatigue degrades reaction time, attention, working memory and judgement, and it increases the likelihood of errors and microsleeps. These effects are particularly dangerous in instrument flight where vigilance is essential. Fatigue is not limited to physical strength and does not improve concentration.

Question 37Basic Aviation Physiology and Health

A pilot who has been awake for 20 hours is most likely to show which pattern of impairment?

  1. Improved performance on complex tasks
  2. Performance similar to a blood alcohol concentration above the legal limit Correct answer.
  3. Reduced performance only on physical tasks
  4. No change in reaction time

Explanation

Prolonged wakefulness produces cognitive impairment comparable to alcohol intoxication, affecting vigilance, reaction time and decision-making. Complex tasks are especially vulnerable. Physical tasks alone are not the only area affected.

Question 38Basic Aviation Physiology and Health

Which measure best reduces the risk of hypoxia during a flight in an unpressurised aircraft above 10,000 feet?

  1. Drink more water.
  2. Increase cabin temperature.
  3. Use supplementary oxygen and limit time at altitude. Correct answer.
  4. Reduce airspeed.

Explanation

Above about 10,000 feet, supplementary oxygen is the most direct way to maintain adequate blood oxygenation, and limiting exposure time reduces cumulative risk. Other measures such as temperature control, airspeed and hydration do not address the oxygen partial pressure.

Question 39Basic Aviation Physiology and Health

What is the main physiological concern when a pilot with a history of epilepsy is considered for flying?

  1. The pilot's ability to tolerate noise
  2. The risk of sudden incapacitation from a seizure in flight Correct answer.
  3. The pilot's colour vision
  4. The effect of altitude on seizure threshold only

Explanation

The primary aeromedical concern with epilepsy is the possibility of a seizure causing sudden incapacitation in flight. Assessment therefore considers seizure history, medication and the interval since the last event. Noise tolerance and colour vision are separate issues.

Question 40Basic Aviation Physiology and Health

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

  1. Blood pools in the lower body, reducing cerebral perfusion and leading to greyout. Correct answer.
  2. Blood is displaced toward the head, increasing cerebral blood flow.
  3. Positive G has no effect on vision.
  4. Positive G improves cardiac output and alertness.

Explanation

Positive G forces blood away from the head toward the lower body, reducing venous return and cerebral perfusion. This produces visual symptoms such as greyout and can progress to G-LOC. It does not increase cerebral blood flow or improve alertness.

Question 41The Nervous System, Vision and Hearing

In a pilot with a normal, healthy visual system, which structure is primarily responsible for the highest acuity (sharpest) central vision?

  1. The optic disc
  2. The cone-rich fovea centralis Correct answer.
  3. The ciliary muscle
  4. The rod-rich peripheral retina

Explanation

The fovea centralis lies at the centre of the macula and contains a dense concentration of cones with minimal convergence onto ganglion cells, giving the highest visual acuity. Peripheral retina is rod-dominated and tuned for dim light and movement detection, not detail. The optic disc has no photoreceptors at all.

Question 42The Nervous System, Vision and Hearing

During a night approach, a pilot deliberately looks slightly to one side of a dimly lit object rather than directly at it. What is the physiological basis for this technique?

  1. Rod density is higher away from the fovea, improving dim-light detection Correct answer.
  2. The optic disc provides better night vision when the eye is turned
  3. Cones are more sensitive to low light than rods and need off-axis viewing
  4. Off-centre viewing increases the size of the pupil and light intake

Explanation

Rods, which mediate scotopic vision, are absent from the fovea and reach maximum density in a ring around it, so a dim target is detected better when its image falls slightly off-centre. This is the basis of the off-centre viewing technique used at night. Cone sensitivity and pupil size are not the mechanism involved.

Question 43The Nervous System, Vision and Hearing

A pilot's dark adaptation is being considered before a night flight. Which statement correctly describes dark adaptation?

  1. It is essentially complete within the first 60 seconds of darkness
  2. It depends mainly on the lens changing shape to admit more light
  3. It is achieved by staring directly at a bright light source before flight
  4. It is a slow process, taking roughly 20 to 30 minutes for full rod sensitivity Correct answer.

Explanation

Dark adaptation involves regeneration of rhodopsin in the rods and takes on the order of 20 to 30 minutes to approach full sensitivity. The early rapid phase is small, and the major gain comes slowly. Lens accommodation and exposure to bright light do not accelerate the process.

Question 44The Nervous System, Vision and Hearing

A pilot is exposed to a bright flash of light at night. Which consequence is most directly attributable to the bleaching of visual pigment?

  1. Temporary loss of night vision that recovers gradually over many minutes Correct answer.
  2. Permanent damage to the optic nerve
  3. Immediate loss of colour vision in daylight
  4. Loss of the ability to accommodate for near objects

Explanation

Bright light bleaches rhodopsin in the rods, so scotopic sensitivity is temporarily reduced and recovers slowly as the pigment regenerates. This is why pilots avoid white light before and during night operations. It does not cause optic nerve damage, daytime colour loss, or accommodation failure.

Question 45The Nervous System, Vision and Hearing

Which statement best describes the functional difference between rods and cones in the human retina?

  1. Rods function in dim light without colour discrimination; cones provide colour and high acuity Correct answer.
  2. Both rods and cones provide colour vision but rods are faster to adapt
  3. Cones are more numerous in the peripheral retina than rods
  4. Rods provide colour vision and cones function only in dim light

Explanation

Rods are highly light-sensitive, support scotopic vision, and do not discriminate colour; cones operate at higher light levels and provide colour vision and fine detail. Their distribution differs, with cones concentrated centrally. The other options invert these well-established roles.

Question 46The Nervous System, Vision and Hearing

An examiner asks a candidate to explain the blind spot. Which description is correct?

  1. It is the area of highest cone density at the centre of the macula
  2. It is the region where the lens is thinnest and focus is poorest
  3. It is the point where the optic nerve leaves the eye and where no photoreceptors exist Correct answer.
  4. It is a zone of the peripheral retina where rods are absent

Explanation

The optic disc is the exit point for ganglion cell axons forming the optic nerve, and it lacks photoreceptors, creating a physiological blind spot. Normal visual fields fill this in, so it is not usually noticed. The other options describe structures with different functions.

Question 47The Nervous System, Vision and Hearing

A pilot's visual field is tested. Which statement about the normal monocular visual field is correct?

  1. The nasal field extends further than the temporal field
  2. The field is symmetrical in all meridians around fixation
  3. The superior field is the largest sector in all directions
  4. The temporal field extends further than the nasal field Correct answer.

Explanation

Because the nose blocks the nasal side, the normal monocular field extends further temporally (roughly to 90 degrees or more) than nasally (around 60 degrees). The field is therefore not symmetrical. This asymmetry has practical relevance for scanning and collision avoidance.

Question 48The Nervous System, Vision and Hearing

A pilot is scanning for traffic outside the cockpit. Why is a deliberate, systematic scanning pattern preferred over staring fixedly at one point?

  1. A small central area gives high acuity, so the eyes must be moved to cover the field Correct answer.
  2. The peripheral retina provides the sharpest image and should be aimed at each target
  3. Eye movements reduce the size of the blind spot
  4. Fixation improves rod sensitivity, so staring is more effective at night

Explanation

High-acuity vision is restricted to the fovea, a very small central region, so targets must be brought onto it by eye movement to be resolved. A structured scan moves fixation across the field. Peripheral retina and fixation do not provide sharper detail, and eye movement does not abolish the blind spot.

Question 49The Nervous System, Vision and Hearing

Which change in vision is most characteristic of ageing in a pilot approaching later middle age?

  1. Improved dark adaptation compared with youth
  2. Increased rod density in the fovea
  3. Increased peripheral visual field extent
  4. Reduced amplitude of accommodation for near focus Correct answer.

Explanation

Presbyopia reflects loss of lens elasticity and reduced accommodative amplitude, so near focus becomes difficult. Other age-related changes tend to be adverse, such as slower dark adaptation and reduced contrast sensitivity. Peripheral field extent and foveal rod density do not increase with age.

Question 50The Nervous System, Vision and Hearing

A pilot reports difficulty judging distance and closing rate on final approach. Which cue is most useful for this judgement at typical approach distances?

  1. Motion parallax and changing retinal image size Correct answer.
  2. Accommodation of the lens alone
  3. Pupil diameter
  4. Colour saturation of the runway lights

Explanation

At distances beyond a few metres, cues such as motion parallax, retinal image size change, and texture gradient dominate distance and closure-rate judgement. Accommodation contributes only at very short range. Colour saturation and pupil size are not reliable distance cues.