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DGCA Air Regulations · 184 questions

Human Performance & Limitations: DGCA Air Regulations Questions and Answers

184 practice questions on Human Performance & Limitations with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.

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About this topic

Use this page to revise Human Performance & Limitations for the DGCA Air Regulations paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 184 questions in the TrueHeading bank for this topic.

In short: Not enough oxygen reaching the tissues:

Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.

Key concepts: Human Performance & Limitations

9 ideas to know cold.

Types of hypoxia?

Not enough oxygen reaching the tissues:

  • Hypoxic: low partial pressure of oxygen (altitude)
  • Stagnant: poor circulation (g-forces, cold)
  • Anaemic: blood cannot carry oxygen (carbon monoxide, anaemia)
  • Histotoxic: cells cannot use oxygen (alcohol, drugs)

Time of useful consciousness?

The time you can act sensibly after losing oxygen supply:

  • FL 180: 20–30 min · FL 220: about 10 min
  • FL 250: 3–5 min · FL 280: 2.5–3 min
  • FL 300: 1–2 min · FL 350: 30–60 s
  • FL 400: 15–20 s · FL 430 and above: 9–12 s

Tip: Cabin altitude, not flight level, in a pressurised aircraft.

Hyperventilation and carbon monoxide?

Hyperventilation: over-breathing lowers CO₂, causing tingling, dizziness. Breathe slowly or into a bag. CO poisoning: haemoglobin binds CO about 200 times more strongly than oxygen.

  • CO sources: exhaust and heater leaks, smokers
  • Treat with 100 % oxygen and fresh air

Decompression sickness and diving?

Nitrogen bubbles form when ambient pressure falls fast.

  • Wait 12 h after a no-decompression dive before flying (up to 8000 ft cabin altitude)
  • Wait 24 h after a decompression dive or before flying above 8000 ft
  • Symptoms: joint pain (the bends), chokes, rash

The eye: rods and cones?

Cones (fovea): colour and detail, daylight. Rods (periphery): dim light, no colour.

  • Dark adaptation takes 30–45 minutes
  • At night look slightly off-centre to use the rods
  • The blind spot is where the optic nerve leaves the eye

Spatial disorientation illusions?

The inner ear misleads you without visual references:

  • Leans: after a slow roll, a correction feels like banking
  • Graveyard spiral: unnoticed spiral with rising speed
  • Somatogravic: acceleration feels like pitching up
  • Black hole: approach over unlit terrain looks too high
  • Autokinesis: a static light seems to move

Tip: Trust your instruments over your senses.

Human factors models?

Reason’s Swiss cheese model: accidents occur when holes in many defences line up. The SHELL model: Software, Hardware, Environment, Liveware (central), Liveware (others).

  • TEM: threats, errors and undesired states
  • Yerkes–Dodson: performance peaks at moderate arousal, drops with too little or too much
  • Cabin altitude in pressurised flight is kept at or below 8000 ft

Describe hypoxia and its types.

A shortage of oxygen in the body tissues.

  • Hypoxic: low partial pressure of O₂
  • Hypaemic: reduced blood capacity (CO)
  • Stagnant: poor circulation
  • Histotoxic: poisoned cells (alcohol)
  • Time of useful consciousness at FL350: 30–60 s; FL250: 3–5 min

What are common spatial disorientation illusions?

Leans, graveyard spin/spiral, somatogravic (false climb on acceleration), black hole, autokinetic, false horizon.

  • Trust the instruments
  • Vestibular system cannot sense constant rate turns
  • Treatment: cross-check attitude indicator

Practice questions: Human Performance & Limitations

Tap “Show answer” after you have tried each one.

Q1Hypoxia is:

  1. a lack of carbon dioxide
  2. excessive breathing
  3. an excess of oxygen
  4. a deficiency of oxygen reaching the tissues of the body
Show answer

Answer: D. a deficiency of oxygen reaching the tissues of the body

Symptoms include euphoria, impaired judgement, headache, blue lips and fingernails.

Q2The time of useful consciousness at 35 000 ft after a rapid decompression is approximately:

  1. 5 minutes
  2. 30 to 60 seconds
  3. 2 hours
  4. 10 minutes
Show answer

Answer: B. 30 to 60 seconds

At 25 000 ft: 3–5 min; 30 000 ft: 1–2 min; 35 000 ft: 30–60 s; 40 000 ft: 15–20 s.

Q3Carbon monoxide poisoning is dangerous because:

  1. it freezes the blood
  2. it causes decompression
  3. it makes the air thin
  4. it combines with haemoglobin over 200 times more readily than oxygen
Show answer

Answer: D. it combines with haemoglobin over 200 times more readily than oxygen

Symptoms: headache, drowsiness, dizziness; sources: faulty exhaust heating, smoking.

Q4Dental barodontalgia is:

  1. tooth pain due to trapped gas in dental cavities at altitude
  2. gum disease
  3. sinus pain only
  4. loss of teeth
Show answer

Answer: A. tooth pain due to trapped gas in dental cavities at altitude

Often during climb.

Q5To see a faint object at night, the pilot should:

  1. look directly at it
  2. look slightly to one side of the object (off-centre viewing)
  3. wear sunglasses
  4. close one eye
Show answer

Answer: B. look slightly to one side of the object (off-centre viewing)

Using the rods around the fovea.

Q6The autokinetic illusion is when:

  1. sounds are louder
  2. the runway appears longer
  3. the horizon tilts
  4. a stationary light appears to move when stared at in darkness
Show answer

Answer: D. a stationary light appears to move when stared at in darkness

Cure: move the eyes and scan frequently.

Q7The vestibular organs of the inner ear detecting angular acceleration are the:

  1. tympanic membrane
  2. semicircular canals
  3. cochlea
  4. otoliths
Show answer

Answer: B. semicircular canals

The otoliths detect linear acceleration and gravity.

Q8G-LOC is:

  1. a lack of oxygen
  2. too much carbon dioxide
  3. G-induced loss of consciousness due to blood draining away from the brain
  4. vision loss from light
Show answer

Answer: C. G-induced loss of consciousness due to blood draining away from the brain

Positive G forces push the blood towards the feet.

Q9Fatigue is best countered by:

  1. nicotine
  2. adequate sleep and rest
  3. coffee
  4. alcohol
Show answer

Answer: B. adequate sleep and rest

Caffeine gives only short-term relief.

Q10Threat and error management (TEM) involves:

  1. avoiding all duties
  2. anticipating threats and errors and managing them before they affect safety
  3. ignoring errors
  4. removing the checklist
Show answer

Answer: B. anticipating threats and errors and managing them before they affect safety

Threats come from the environment; errors from the crew.

Q11Optimum performance occurs at:

  1. no arousal
  2. extreme arousal
  3. sleep
  4. a moderate level of arousal
Show answer

Answer: D. a moderate level of arousal

The Yerkes-Dodson law: performance rises with arousal to a point and then falls.

Q12A pilot with a cold should not fly because:

  1. it makes him sleepy only
  2. blocked Eustachian tubes can cause severe pain and damage on descent
  3. of colour blindness
  4. of the language barrier
Show answer

Answer: B. blocked Eustachian tubes can cause severe pain and damage on descent

Barotrauma can damage the eardrum.

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