DGCA Air Regulations: Human Performance & Limitations Questions

Correct answer: B. Three Greens Landing gear down and locked)

THREE GREENS is the call made by the Pilot Monitoring PM) during approach to confirm that all THREE landing gear are DOWN AND LOCKED — each gear has a green indicator light. The PF Pilot Flying) calls for gear down, the PM selects it, then confirms Three greens when all three lights illuminate green. This is a mandatory check before landing!

Correct answer: D. 1, 3

Statement 1 is CORRECT — rods are in the peripheral retina, cones are in the central zone fovea). Statement 3 is CORRECT — rods enable night vision. Statement 2 is WRONG — the crystalline lens is just a focusing lens, it has no photoreceptors at all! Statement 4 is WRONG — cones are CENTRAL not peripheral. So 1 and 3 are correct!

Correct answer: B. Good night-vision after adaptation to darkness 30 min)

RODS are the night-vision cells but they need 25-30 minutes to fully adapt to darkness — they are NOT instant! This is why you should never look at a bright light before a night flight. Rods don't detect colour that's CONES) — night vision is mostly grayscale. The key fact: rods = night vision, but only after dark adaptation!

Correct answer: B. 2, 4

Central vision uses CONES not rods — so statement 1 is WRONG). Cones give you sharp colour and detail vision statement 2 is CORRECT). The fovea has ~150,000 cones per mm² for high resolution statement 4 is CORRECT). Statement 3 is WRONG because cones need bright light — central vision is poor at night. Answer: 2 and 4 only!

Correct answer: C. Both hyperventilation and pressure breathing

Hypoxia can cause BOTH hyperventilation breathing too fast as the body tries to get more oxygen) AND pressure breathing a technique where oxygen is forced in under pressure at very high altitudes). So both responses are associated with hypoxia depending on the situation and altitude.

Correct answer: B. Lethargy, nausea, headache and change in complexion

Carbon monoxide poisoning causes: lethargy tiredness), nausea feeling sick), headache, and a cherry-red or strange complexion. CO is the sneaky killer because it has no smell. The headache is often the first warning. In cockpits, it usually comes from heating systems that use engine exhaust heat.

Correct answer: A. Leans

The LEANS is a spatial disorientation problem feeling like you are tilted when you are not) — it is NOT a decompression sickness symptom. Bends joint pain) and Chokes respiratory distress from gas bubbles) ARE decompression sickness symptoms. The leans is a vestibular/inner ear problem, not a gas bubble problem.

Correct answer: B. Hyperventilation

Dizziness, tingling in hands, and rapid heart rate during a stressful approach are classic signs of HYPERVENTILATION — breathing too fast. When you are nervous you breathe too quickly, blow off too much CO2, and these symptoms appear. The fix is to slow your breathing down, not to use oxygen.

Correct answer: B. Is constant for all altitudes conventional airplanes can reach

The percentage of oxygen in the air is always about 21% — it does not change with altitude. What DOES change is the air pressure, which means the oxygen molecules are more spread out up high. So there is the same fraction of oxygen but each breath gives you less of it. The percentage stays, the pressure d rops.

Correct answer: B. Is more likely to occur in aeroplanes where the cabin heat is technically supplied by coating the exhaust

Carbon monoxide poisoning is more likely in aircraft where cabin heating comes from passing air over the exhaust common in piston aircraft). If the exhaust system has any cracks or leaks, CO gas sneaks into the heated air going to the cabin. Always check your CO detector before flight!

Correct answer: D. In the red blood cells

Haemoglobin is found inside red blood cells. It is the special protein that grabs oxygen and carries it around your body. Think of red blood cells as little taxis and haemoglobin as the seat — oxygen sits in the haemoglobin seat for the ride.

Correct answer: C. Due to pressure differentials between gases in hollow cavities of the body and the ambient pressure

Barotrauma happens because the air pressure outside changes faster than the air pressure inside your body cavities like ears, sinuses). Imagine squeezing a plastic bottle — the pressure difference is what causes the damage. It is all about the pressure difference between inside and outside your body.