Aviation Physiology and Human FactorsAir Regulations — DGCA CPL practice questions

Question 1 of 54

In a severe case of hypoxia:

A.Only brain and heart functions are maintained.

B.Only blood pressure and heart functions are maintained.

C.Only blood pressure and brain functions are maintained.

All 54 questions — Aviation Physiology and Human Factors

Air Regulations · DGCA CPL. The correct option is marked on each.

Q1. In a severe case of hypoxia:
- A.Only brain and heart functions are maintained.
- B.Only blood pressure and heart functions are maintained.✓
- C.Only blood pressure and brain functions are maintained.
Why: In severe (terminal) hypoxia, higher cortical functions fail first → loss of consciousness. Reflex BP and cardiac function are maintained by brainstem mechanisms even as the cortex shuts down. The brain (cortex) is in fact the most sensitive tissue to hypoxia and fails before the heart. Hence "blood pressure and heart functions" (autonomic/brainstem) are retained while higher brain function is lost.
Q2. Generally, active pilots should not donate blood, because:
- A.The loss of blood causes permanent disturbances to the circulation.
- B.The fluid reduction caused by donating one unit of blood is generally replaced within several weeks.
- C.The effects at ground level are minimal, flying during this period may entail a risk.✓
Why: DGCA-quoted verbatim: "While the effects at ground level are minimal, flying during this period may entail a risk." (A) is too strong — "permanent" disturbances would prevent donation entirely. (B) is factually wrong on the time scale — fluid volume is replaced in hours, while red cell mass takes weeks.
Q3. In mild cases, hypoxia causes only:
- A.Inattentiveness, poor judgment, and brain stem reflexes.
- B.Inattentiveness, poor judgment, and uncoordinated movement.✓
- C.State of complete unawareness and unresponsiveness.
Why: Mild hypoxia attacks cognitive and motor functions: inattention, impaired judgement, slow reactions, and uncoordinated movement (clumsy fine motor). (A) — brainstem reflexes are retained in mild hypoxia, not lost. (C) — complete unawareness is severe/terminal hypoxia (Q51).
Q4. During an extensive gym work out one experiences:
- A.Angina due to increased blood circulation.
- B.Hypoxia due to lack of oxygen.
- C.Hyperventilation due to excessive CO₂ in blood.✓
Why: Heavy exercise → increased muscle metabolism → increased CO₂ production → respiratory centre drives increased ventilation (hyperventilation) to blow off the excess CO₂. (A) Angina would only occur if coronary supply was inadequate (pathology, not normal exercise). (B) Hypoxia is unlikely with normal lungs at sea level.
Q5. The symptoms of CO poisoning are:
- A.Memory Impairment, Sensory Loss, Tunnel Vision, Cyanosis (a bluing of the body extremities).
- B.Headache, Dizziness, Nausea, Impaired vision.✓
- C.Impaired Judgment, Headache, Tingling in hands & feet, Hyperventilation.
Why: Classic CO poisoning: headache, dizziness, nausea, impaired vision, progressing to confusion and unconsciousness. (A) Cyanosis is the wrong colour — CO poisoning gives cherry-RED lips/skin (carboxyhaemoglobin is bright red), not blue. (C) Tingling and hyperventilation cluster matches hyperventilation/hypoxia signs, not CO specifically.
Q6. In severe hypothermia, core body temperature can drop below:
- A.95 degrees.
- B.90 degrees.
- C.82 degrees.✓
Why: DGCA-quoted: normal 98.6 °F · hypothermia < 95 °F · severe hypothermia: core ≤ 82 °F (or lower). Option A (95 °F) is the threshold for "mild" hypothermia entry, not severe.
Q7. A pilot, climbing in a non-pressurized aircraft and without using supplemental oxygen will pass the "critical threshold" at approximately:
- A.22,000 feet.✓
- B.18,000 feet.
- C.10,000 feet.
Why: DGCA-quoted: the critical threshold for unpressurized flight without supplemental oxygen is ~22,000 ft (within the Physiologically Deficient Zone). Above 22,000 ft a pressurised cabin or a pressure-breathing system is required. Note: 38,000 ft is the upper limit even with 100 % O₂.
Q8. In a steep turn at 26,000 feet, you experience a loss of muscular coordination. What should be your actions?
- A.Breathe oxygen at 100 percent. If hypoxia is the cause, the symptoms will improve markedly after three or four breaths. If the symptoms persist, consciously slow the rate of breathing to 10–12 breaths per minute.✓
- B.Breathe oxygen at 100 percent. If Hyper ventilation is the cause, the symptoms will improve markedly after three or four breaths. If the symptoms persist, consciously increase the rate of breathing to 30–32 breaths per minute.
- C.Breathe oxygen at 100 percent. If CO poisoning is the cause, the symptoms will improve markedly after three or four breaths. If the symptoms persist, land as soon as possible.
Why: DGCA-quoted differential diagnosis: at altitude, suspect hypoxia FIRST → put on 100 % O₂. If symptoms improve in 3-4 breaths → hypoxia confirmed. If symptoms persist → suspect hyperventilation → consciously slow breathing to 10-12 breaths/min (NOT increase). (B) increases breathing rate — wrong; that would worsen hyperventilation. (C) — CO poisoning is rare at altitude in unheated aircraft.
Q9. While flying solo, suddenly your mood changes to intense feelings of well-being and happiness. Your actions should be:
- A.Plan a date with your girlfriend.
- B.Enjoy the flight singing favorite songs.
- C.Suspect onset of hypoxia. Take oxygen and descend below 10,000 feet.✓
Why: A sudden onset of euphoria / wellbeing with no objective cause at altitude is a classic early hypoxia warning (§41 question above also tested this). Standard immediate action: 100 % O₂ + descend below 10,000 ft. This is the most "trap-style" question in the bank — picking A or B confirms you've fallen for the very illusion the question warns about.
Q10. A pressurized cabin is necessary to protect against:
- A.Decompression sickness, expansion of gases in the intestines and hypoxia.✓
- B.Decompression sickness, UV rays and hypoxia.
- C.Expansion of gases in the intestines, heart attack and hypoxia.
Why: A pressurised cabin keeps cabin altitude low (≤8,000 ft) which simultaneously prevents: Hypoxia — low pO₂ at altitude (Dalton's Law) DCS — N₂ bubbles when pressure drops too low (Henry's Law) Gut/sinus/dental gas expansion — Boyle's Law (B) UV rays are filtered by cockpit windows (§31.6), pressurisation does not protect against UV. (C) Heart attack is not pressure-related.
Q11. What is the "Time of Useful Consciousness" for a progressive decompression at 20,000 ft?
- A.Between 15 and 20 minutes depending on the physical activities being performed.
- B.Between 45 seconds and 2 minutes depending on the physical activities being performed.
- C.Between 5 and 10 minutes depending on the physical activities being performed.✓
Why: DGCA TUC table: FL220 (22,000 ft) — normal ascent TUC = 10 minutes; rapid decompression at FL220 = 5 minutes. So a "progressive" (slow) decompression at 20,000 ft falls between FL180 (20-30 min) and FL220 (10 min) — approximately 5-10 minutes. Option (C) is the closest band.
Q12. Hypobaric hypoxia is a result of:
- A.Exposure to high temperatures.
- B.High blood alcohol levels in blood.
- C.Exposure to high altitude.✓
Why: Hypobaric hypoxia = "low-pressure" hypoxia = the hypoxia caused by reduced atmospheric pressure at altitude. It's another name for hypoxic hypoxia. (A) heat → heat stress / dehydration, not hypoxia per se. (B) alcohol → histotoxic hypoxia (cells can't use O₂), a different sub-type.
Q13. Otis Barotraumas is due to stretching of the ear drum caused by:
- A.The expansion and contraction of gases trapped in the inner ear by a blocked Eustachian tube.✓
- B.The expansion and contraction of gases trapped in the middle ear due damage to the hearing mechanism.
- C.The expansion and contraction of gases trapped in the middle ear due to build up of wax.
Why: DGCA-quoted, including the source's looseness about "inner ear" (anatomically the trapped gases are in the middle ear, but the source text and the answer key both use "inner ear"). The cause is a blocked Eustachian tube. Wax build-up (option C) affects the external auditory canal, not the middle-ear pressure equalisation.
Q14. The release of nitrogen bubbles due to decompression can adversely affect:
- A.Joints, skin, respiratory system and brain.✓
- B.Joints, skin, inner ear and brain.
- C.Vision, liver, respiratory system and brain.
Why: The four DGCA-quoted DCS syndromes target: Joints (Bends) · Skin (Creeps) · Respiratory system (Chokes) · Brain (Staggers). Option A matches all four. (B) inner ear is not in the canonical list. (C) liver / vision are not classical DCS targets.
Q15. Myocardial infarction refers to:
- A.A brain attack when high blood flow causes damage to brain nerves.
- B.A heart attack when low blood flow causes the heart to starve for oxygen.✓
- C.Expansion of trapped gases in intestine at high altitude causing severe pain in the chest.
Why: "Myocardial infarction" = "death of (infarction) heart muscle (myocardium)" — i.e. a heart attack, caused when a coronary artery is blocked (typically by a plaque + clot) and the muscle distal to the blockage is starved of oxygen. (A) describes a stroke (brain attack), not MI. (C) describes gas-expansion chest pain — wrong mechanism.
Q16. Dehydration due to low relative humidity at high altitude can be prevented with:
- A.Excessive fluid intake.
- B.Adequate fluid intake.✓
- C.Diuretics like coffee or tea to be taken frequently.
Why: DGCA-quoted: "Over-all dehydration can be prevented with ADEQUATE fluid intake. Diuretics like coffee or tea should be AVOIDED." (A) "excessive" is wrong — over-hydration is also problematic (water intoxication, frequent bathroom breaks). (C) is the exact opposite of what DGCA prescribes — coffee and tea are diuretics.
Q17. Oxygen in blood is carried by, which is found in:
- A.Hemoglobin, white blood cells.
- B.Hemoglobin, red blood cells.✓
- C.Red blood cells, platelets.
Why: Oxygen binds to haemoglobin, which is contained inside red blood cells. (A) Hb is NOT in WBCs — WBCs are immune cells. (C) Garbled — platelets are for clotting, not gas transport.
Q18. What does Visual Acuity stand for?
- A.Is the capacity of the eye to determine small detail, undistorted, at a given distance.✓
- B.Time taken for night vision adaptation.
- C.Distance at which one can see objects undistorted under dim and bright Illumination.
Why: DGCA-quoted definition verbatim: "Visual acuity is a measure of the capacity of the eye to determine SMALL DETAIL, UNDISTORTED, at a given distance." (B) describes dark adaptation. (C) is a vague distractor.
Q19. Out of the following, which are different types of Hypoxia?
- A.Hypoxic, Anemic, Ischemic, Histotoxic.✓
- B.Hypoxic, Anemic, Ischemic, Asphyxiation.
- C.Hypoxic, Anemic, Compression, Histotoxic.
Why: DGCA-quoted four types: Hypoxic · Anemic · Ischemic (Stagnant) · Histotoxic. Asphyxiation and "Compression" are not standard names for hypoxia subtypes.
Q20. Flying a Cessna 172 at 6,000 feet with heaters on, you develop breathlessness. The most probable reason could be due to:
- A.Hypoxic Hypoxia.
- B.Anemic Hypoxia as a result of CO poisoning.✓
- C.Ischemic Hypoxia as a result of CO poisoning.
Why: Key cue: "heaters ON" in a piston single. Cabin heating in light aircraft works by drawing air past the exhaust manifold — if there's a crack, CO leaks into the cabin. CO binds to haemoglobin 200× more readily than O₂ → effectively a reduced-Hb situation = Anemic hypoxia. (A) Hypoxic hypoxia is altitude-driven — 6,000 ft is too low. (C) Ischemic = blood flow problem.
Q21. Flying Cessna 172 at 6,000 feet without heaters on, you feel sick, suffer blurred vision and feel weak. The most probable reason could be due to:
- A.High BP resulting in Ischemic hypoxia/stagnant hypoxia, curable by taking 100% oxygen for 2-3 minutes.
- B.Low BP resulting in Ischemic hypoxia/stagnant hypoxia, curable by taking 100% oxygen for 2-3 minutes.
- C.Low BP resulting in Ischemic hypoxia/stagnant hypoxia, taking 100% oxygen doesn't help.✓
Why: Key cues: "heaters OFF" (excludes CO) + sick/blurred/weak + at low altitude. Low BP / poor circulation → blood not reaching tissues = Ischemic (stagnant) hypoxia. Critical learning point: in stagnant hypoxia, the air has plenty of O₂ — the problem is delivery. Breathing 100 % O₂ does NOT help because the blood isn't flowing properly to carry it. (A) High BP would tend to push more blood, not less. (B) is the trap — 100% O₂ does not cure ischemic hypoxia.
Q22. Flying a Cessna 172 at 6,000 feet without heaters on, you feel difficulty breathing and rapid heart rate. You remember having excessive drinks in a party previous night. The most probable reason could be due to:
- A.Histotoxic Hypoxia.✓
- B.Hypoxic Hypoxia.
- C.Ischemic Hypoxia.
Why: Alcohol the night before → still circulating. Alcohol is a classic cause of histotoxic hypoxia — the tissues can't use O₂ even when it's available. Other causes: CO, cyanide. At 6,000 ft with no heaters and no obvious circulatory cause, alcohol residue is the most likely explanation. This is why the DGCA enforces the 24-hour bottle-to-throttle rule.
Q23. Alcohol leaves the body at an average rate of:
- A.0.050 g/100 mL/hour, for men, this is usually a rate of about half standard drink per hour.
- B.0.035 g/100 mL/hour, for men, this is usually a rate of about quarter standard drink per hour.
- C.0.015 g/100 mL/hour, for men, this is usually a rate of about one standard drink per hour.✓
Why: DGCA-quoted metabolism rate: 0.015 g/100 mL/hour = ~one standard drink per hour. This is why a heavy drinking session takes many hours to clear — the body cannot accelerate alcohol metabolism.
Q24. You can overcome hyperventilation by:
- A.Consciously increasing the rate of breathing to 18–20 breaths per minute.
- B.Breathing deeply to raise the level of oxygen in blood.
- C.Breathing into a paper bag to raise the level of CO₂ in the blood.✓
Why: Hyperventilation = over-breathing → CO₂ blown off → respiratory alkalosis → symptoms. Cure: raise CO₂ by breathing into a paper bag (re-breathing your own exhaled CO₂) OR consciously slowing breathing to 10-12 breaths/min. (A) increasing rate makes it worse. (B) deeper/faster breathing also makes it worse — the problem is too little CO₂, not too little O₂.
Q25. While joining circuit, you start breathing heavily, feel dizzy, get tingling sensations in your feet and a rapid heart rate. Your actions are:
- A.Suspect carbon monoxide poisoning, take 100% oxygen, turn off cabin heating and open ventilation.
- B.Suspect hypoxia, take 100% oxygen, land at the earliest and report to an aviation medicine specialist.
- C.Suspect hyperventilation, raise CO₂ level by breathing in a paper bag or consciously lowering breathing rate or shouting loudly.✓
Why: Key cues: low altitude (circuit) + heavy breathing + tingling + rapid heart rate. Hypoxia is unlikely in circuit altitude. CO poisoning would typically present with headache and nausea, not tingling. The tingling in extremities is a classic hyperventilation sign (respiratory alkalosis → tetany). Cure as in Q75. Note: shouting works because it forces longer, slower exhalations.
Q26. Symptoms caused by gas bubbles in the lungs, following a decompression are called:
- A.Chokes✓
- B.Bbends
- C.Staggers
Why: Bubbles in lungs (respiratory system) → CHOKES (shortness of breath, burning gnawing piercing chest pain). Mnemonic: Joints Bend · Skin Creeps · Lungs CHOKE · Brain Staggers.
Q27. The chance of a black-out during positive G Maneuvers can be reduced by:
- A.Engaging autopilot.
- B.A tilted back seat.✓
- C.Applying negative G.
Why: DGCA-quoted verbatim: "A tilted back seat can reduce the chance of a black-out during positive G-manoeuvres." The reclined seat shortens the hydrostatic blood column from heart to brain, preserving cerebral perfusion at higher G. Negative G (C) would cause red-out — not a useful counter to blackout!
Q28. During sustained positive G-forces the order of symptoms is:
- A.Diminished awareness, Tiredness, Lack of coordination, Black out.
- B.Internal organs displaced, Onset of tunnel vision, Grey out, Possible black out.✓
- C.Memory lapses, Frequent mistakes in speech and actions, Rapid changes of mood, Grey out.
Why: DGCA-quoted order: 1. Increase in body weight · 2. Mobility impaired · 3. Internal organs displaced · 4. Onset of tunnel vision · 5. Grey out · 6. Possible blackout. Option B preserves the correct 3→4→5→6 sequence. (A) and (C) describe hypoxia-style mental symptoms, not the G cascade.
Q29. Hemoglobin, the oxygen-carrying chemical in the blood, picks up:
- A.Carbon monoxide over 200 times more readily than it picks up oxygen.✓
- B.Carbon dioxide over 10 times more readily than it picks up oxygen.
- C.Oxygen over 5 times more readily than it picks up nitrogen.
Why: DGCA-quoted: haemoglobin binds CO ~200 times more readily than O₂ — which is why even small CO concentrations are catastrophic. (B) the CO₂-Hb relationship is via carbamino bonds and is reversible — not the right framing. (C) Hb doesn't significantly bind nitrogen.
Q30. Carbon monoxide is a:
- A.Light blue, odorless, tasteless gas.
- B.Colorless, odorless, tasteless gas.✓
- C.Colorless, foul smelling, tasteless gas.
Why: CO = colourless, odourless, tasteless → the "silent killer". This is precisely why CO detectors are required in modern light aircraft and homes — humans cannot detect CO with their senses.
Q31. Why most pilots can learn to tolerate moderate increases in positive "G", but many find even the smallest exposure to negative "G" to be unpleasant?
- A.Negative "G" manoeuvres decrease the flow of blood to the head, the face becomes white, and the vision becomes blurred.
- B.Negative "G" manoeuvres increase the flow of blood to the head, the face becomes very flushed, and the eyes bulge.✓
- C.Black out occurs in quick succession after a red out, allowing hardly any reaction time.
Why: DGCA-quoted verbatim. Negative G pushes blood UP into the head → face flushed, eyes bulge, "red out". The human body has no compensatory reflex for this direction (the baroreceptor reflex is built to maintain cerebral pressure under positive G, not under negative G).
Q32. Barotrauma is caused by:
- A.The trapped gases inside the aircraft which create pain as ambient pressure increases.
- B.The trapped gases inside the body which create pain as ambient pressure decreases.
- C.The trapped gases inside the outer ear, which cause damage to the ossicles or the ear drum.✓
Why: Note: the DGCA answer key marks (C). However the strict definition refers to middle ear trapped gases (not "outer ear" as written). Option (B) — gases in the body, pain as pressure changes — is also technically correct for barotrauma in general. Read this as a context-specific question about ear barotrauma (Otis), where the answer key's option C is to be marked despite the imprecise wording.
Q33. Breathing 100% oxygen will lift the pilot's physiological safe altitude to approximately:
- A.18,000 ft.
- B.22,000 ft.
- C.38,000 ft.✓
Why: DGCA-quoted: with 100 % O₂ supplemental breathing, the maximum safe altitude is 38,000 ft. Above 38,000 ft even pure O₂ at ambient pressure does not provide adequate pO₂ to the alveoli — pressure breathing is required. (A) 18,000 ft is where pressure halves. (B) 22,000 ft is the critical threshold without O₂.
Q34. The retina has about 100 million rods on its peripheral zone. Rods can:
- A.Only detect black and white but are much more sensitive at lower light levels.✓
- B.All colors but are much more sensitive black and white.
- C.Only detect black and white but are much less sensitive at lower light levels.
Why: DGCA-quoted verbatim. Rods = peripheral retina, ~100M, monochrome (B&W only), but extremely sensitive in dim light — they are the basis of night vision. (B) is wrong — rods do NOT detect colour. (C) is reversed — rods are MORE sensitive at low light, not less.
Q35. Depth perception when objects are close is achieved through:
- A.Central Vision.
- B.Visual Acuity.
- C.Binocular Vision.✓
Why: DGCA-quoted: "Depth perception when objects are close is achieved through binocular vision." Each eye sees the same object from slightly different angles; the brain fuses the two images → stereo depth. For distant objects, monocular cues (perspective, motion parallax, atmospheric perspective) dominate.
Q36. Which scanning technique should be used when flying at night?
- A.Increase intensity of cabin lights.
- B.Look to the side of the object.✓
- C.Look directly at the object.
Why: DGCA-quoted: "Look to the side (15-20 deg) of the object." The fovea has only cones (no rods) → no night vision. Looking at a dim target puts it on the fovea = blind at night. Looking 15-20° off-axis puts it on the rod-rich periphery = visible. Counterintuitive but essential. (A) bright cabin lights kill the pilot's dark adaptation (§31.2).
Q37. Flickering light when reflected from helicopter blades or propellers of aircraft rotating at high RPM:
- A.Can not cause any harm, hence no action is required.✓
- B.Can cause Stroboscopic Vertigo, hence make frequent but small changes in RPM.
- C.Can cause nausea, dizziness or unconsciousness, hence land as soon as possible.
Why: Important note: This is one of the answer-key's most counter-intuitive marks. The DGCA-quoted theory clearly states flickering at 4-20 Hz CAN cause flicker vertigo (nausea, dizziness, even epileptic-like reactions), and the mitigation is "make frequent but small changes in RPM" — exactly what option (B) says. The official answer key marks (A) — interpretable as "at HIGH RPM the flicker frequency is above the 4-20 Hz danger band, so no harm occurs." At high RPM the flicker frequency exceeds the dangerous band and no harm results; the problem is during throttle-back / landing when prop slows into the 4-20 Hz range. So (A) is technically accurate for "high RPM" but option (B) describes the correct general mitigation. Mark per the official key (A) in the exam.
Q38. A B-787 pilot feels nausea and dizziness while flying through low clouds. This could be due to:
- A.Somatogravic Effect, take 100% oxygen and climb to a higher altitude.
- B.The leans, get on to the instruments and correct the aircraft attitude.
- C.Stroboscopic Effect, switch off anti-collision lights.✓
Why: DGCA-quoted: "The bounce back from rotating beacons on aircraft which have penetrated clouds [can cause flicker vertigo]. If the beacon is bothersome, shut it off during these periods." Anti-collision strobes reflecting off cloud particles create exactly the 4-20 Hz flicker condition → flicker vertigo (nausea, dizziness). Switching off strobes in cloud is the prescribed cockpit action.
Q39. The primary and most reliable sense of spatial orientation is ____. The balance sensors situated in the ____ provide us with a secondary system.
- A.Ear, Eyesight.
- B.Eyesight, ear.✓
- C.Vestibular apparatus, Somatosensory system.
Why: DGCA-quoted: "The primary and most reliable sense of spatial orientation is EYESIGHT. The balance sensors situated in the EAR provide us with a secondary system." Option B matches the DGCA wording exactly. Option A is reversed.
Q40. The Vestibular apparatus (Otoliths + Semi-circular canals) helps maintain spatial orientation. The Otoliths detect ____. The Semi-Circular Canals detect ____.
- A.Angular acceleration, linear acceleration.
- B.Equilibrium, orientation
- C.Linear acceleration, angular acceleration.✓
Why: DGCA-quoted verbatim. Otoliths = LINEAR acceleration (takeoff, braking, gravity). Semi-Circular Canals = ANGULAR acceleration (turning, pitching, rolling). (A) is reversed. Mnemonic: Otoliths Line · Canals Curve.
Q41. A pilot approaching a runway which is narrower than normal may feel that he is ____ and make an ____.
- A.High, under shooting approach.✓
- B.Low, over shooting approach.
- C.Disoriented, instrument approach (2D).
Why: DGCA-quoted: a narrower-than-usual runway appears to be farther/higher → pilot feels HIGH → reduces descent rate → flies a shallow approach → ends up LOW on final / undershoot / lands short. Wide runway = opposite (feels LOW, steep, lands long). The mnemonic: Narrow → Feels High → Undershoots.
Q42. Human beings maintain spatial orientation using a combination of three factors. Out of these, most reliable is ____, insufficiently reliable is ____ and not at all reliable especially in IMC is ____.
- A.The Somatosensory system ("seat of the pants" feeling)/G-force, The sense of vision, The Vestibular Apparatus.
- B.The Vestibular Apparatus, The Somatosensory system ("seat of the pants" feeling)/G-force, The sense of vision.
- C.The sense of vision, The Vestibular Apparatus, The Somatosensory system ("seat of the pants" feeling)/G-force.✓
Why: DGCA-quoted reliability ranking: Vision (most) → Vestibular (partial) → Somatosensory (not reliable at all). Option C presents them in this exact order. Mnemonic: V·V·S — Vision · Vestibular · Somatosensory.
Q43. Coriolis illusion, causing spatial disorientation is the result of:
- A.Simultaneous head movements during aircraft manoeuvres can give the feeling to pilots that they are pitching, yawing, and rolling simultaneously.✓
- B.The absence of visual cues during IMC manoeuvres.
- C.Because of the lack of stable visual references and the erroneous mental models, the pilot is at a disadvantage.
Why: Coriolis (also called somatogyral cross-coupling) occurs when head movement during a sustained turn excites multiple semi-circular canals simultaneously → brain receives signals as if the aircraft is pitching, yawing, and rolling all at once. The cure: keep head stationary in IMC turns, lock eyes on the attitude indicator.
Q44. The Eustachian tube:
- A.Equalizes pressure between middle ear and external atmosphere.✓
- B.Provides us with our sense of balance.
- C.Helps maintain spatial orientation.
Why: DGCA-quoted: "The Eustachian tube allows pressure in the middle ear to equalize across the ear drum with outside or ambient pressure when climbing or descending." (B) Balance is the function of the vestibular apparatus, NOT the Eustachian tube. (C) Spatial orientation comes from vestibular + vision + somatosensory.
Q45. Night vision can be affected by:
- A.Lack of exercise, High blood pressure, Lack of exercise, Smoking.
- B.Obesity, Too much fat in your diet, Alcohol, Smoking.
- C.Age, hypoxia, altitudes above 8,000 ft, smoking and alcohol.✓
Why: Night vision degraders (cross-referenced from multiple parts): age (presbyopia, lens yellowing), hypoxia (retina is the highest O₂-demand tissue), altitude (impairs dark adaptation above 5,000 ft per §31.2), smoking (CO in carboxyhaemoglobin reduces retinal O₂), alcohol (histotoxic in retinal cells). Option C is the only set that names valid degraders.
Q46. Dark adaptation is impaired by:
- A.Altitudes above 8,000 feet, inhaling carbon monoxide, myopia and exposure to bright sunlight.
- B.Altitudes above 5,000 feet, vibrations, deficiency of Vitamin C and exposure to bright sunlight.
- C.Altitudes above 5,000 feet, inhaling carbon monoxide, deficiency of Vitamin A and exposure to bright sunlight.✓
Why: DGCA-quoted four dark-adaptation impairers: cabin altitude > 5,000 ft · CO (smoking, exhaust) · Vitamin A deficiency · prolonged exposure to bright sunlight. Option C matches all four. (A) "8,000 ft" is wrong threshold; myopia is unrelated. (B) "Vitamin C" is wrong vitamin — Vitamin A is essential for rod function.
Q47. Myopia is more commonly known as ____ and Hypermetropia as ____.
- A.Long-sightedness, Short-sightedness.
- B.Short-sightedness, Long-sightedness.✓
- C.Defective vision, color-defective vision.
Why: Myopia = short-sightedness (can only see things close-up). Hypermetropia = long-sightedness (can only see things at a distance). The Greek roots: "myops" = closed-eye / squinting (originally short-sighted), "hyper-metropia" = above-/over-measure. Option A is reversed. (C) — colour-defective vision is colour blindness (§35).
Q48. Hypothermia is potentially:
- A.A life-threatening condition caused by core body temperature dropping below 95 deg F. It needs emergency medical attention.✓
- B.Not a life-threatening condition, shivering tends to ease discomfort and is followed by full recovery with 100% oxygen.
- C.A shivering condition caused due to low cabin temperature. However, it doesn't have any adverse effect on physical and mental abilities.
Why: DGCA-quoted verbatim: hypothermia begins when core temp drops below 95 °F, is life-threatening, requires emergency medical attention. (B) is dangerously wrong — 100% O₂ does nothing for hypothermia. (C) is wrong — hypothermia DOES affect physical AND mental abilities (DGCA-quoted directly).
Q49. The absence of anything to focus on in a featureless sky (empty field myopia) affects the pilot's capacity to scan for traffic. It can be overcome by:
- A.Periodically and deliberately focusing on objects at a distance.
- B.Periodically and deliberately focusing on objects, both close and at a distance.✓
- C.Periodically and deliberately focusing on objects at the horizon.
Why: DGCA-quoted: "Pilots should minimize the risks associated with empty visual field by periodically and deliberately focusing on objects, BOTH CLOSE AND AT A DISTANCE." The full range exercises the ciliary muscles and breaks the empty-field resting focus (which sits at 1-2 m, inside the cockpit). (A) and (C) only exercise distance vision.
Q50. Normal Body Mass Index, or BMI, for men is ____ and for women ____.
- A.22-30; 20-28.
- B.20-25; 19-24.✓
- C.18-25; 16-23.
Why: DGCA-quoted: Normal BMI: men 20-25 · women 19-24. Option B matches exactly. (A) too high. (C) too low.
Q51. "Oxygen moves from the alveoli into the blood and from the blood into the tissues" this phenomenon is explained by:
- A.Boyle's law.
- B.Charle's law.
- C.Graham's law.✓
Why: Note: this is one of the few questions where the strict gas-law mapping is debatable. Strictly, diffusion of a gas across a membrane down its partial-pressure gradient is governed by Fick's Law and Dalton's Law. Graham's Law strictly addresses the rate of diffusion (proportional to 1/√molecular weight). The DGCA syllabus lumps gas-diffusion problems under Graham's Law as the "rate of diffusion" law — hence option C. Boyle's (A) is pressure-volume, Charles's (B) is volume-temperature.
Q52. The illusions are:
- A.A natural phenomena, organized formal training is the best protective measure against illusions.✓
- B.Abnormal, require psychiatric treatment.
- C.Visual cues with no effective counter measures available to overcome them.
Why: DGCA-quoted: "The illusions are NATURAL PHENOMENA. Organized formal training is the BEST PROTECTIVE MEASURE against illusions." (B) — illusions affect every pilot regardless of mental health. (C) is fatalistic and wrong — many counter-measures exist (instrument flying, training, briefings, etc.)
Q53. Bright runway / app. lights give illusion of being:
- A.High, resulting in low approaches.
- B.Low, resulting in high approaches.✓
- C.On correct approach, resulting in an inadvertent speed loss.
Why: DGCA-quoted: "Down-sloping runway or terrain, wider than usual runway and bright runway/app. lights give illusion of being LOW, resulting in HIGH approaches." Bright lights make the runway look closer → pilot feels low → increases descent rate → steep approach → land long. Mnemonic: Bright = feels low = flies high.
Q54. A dark scene spread with ground lights and stars and obscured sky can create illusions of:
- A.Not being aligned correctly with the actual horizon.✓
- B.Being aligned correctly with the actual horizon.
- C.Being aligned with the artificial horizon.
Why: DGCA-quoted: "A sloping cloud formation, an obscured horizon, and a dark scene spread with ground lights and stars can create an illusion known as FALSE HORIZONS." The pilot misjudges aircraft attitude relative to the true horizon → may place the aircraft in a dangerous attitude. This question — fittingly — is the final question of the source PDF: a complete return to the master rule: "IMC = Instruments. VMC = Horizon."