Category Archives: Human Perf Limit

What counter-measure can be used against barotrauma of the middle ear?

A: Close the mouth, pinch the nose tight and blow out thereby increasing the pressure in the mouth and throat. At the same time try to swallow or move lower jaw
B: Increase rate of descent
C: Stop climbing, start descent
D: Pilots should apply anti-cold remedies prior every flight to prevent barotrauma in the middle ear









Answer: A

Dalton’s law explains the occurrence of:

A: bends
B: altitude hypoxia
C: decompression sickness
D: creeps









Answer: B

Dalton’s law (also called Dalton’s law of partial pressures) states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture.

Which force(s) affect(s) the otoliths in the utriculus and sacculus?

A: Linear acceleration and angular acceleration
B: Gravity alone
C: Gravity and linear acceleration
D: Angular acceleration









Answer: C

The utricle is sensitive to a change in horizontal movement
The saccule gives information about linear acceleration (such as when in an elevator).

Rods (scotopic visual cells) allow for:

A: red vision, both during the day and at night
B: good, virtually instantaneous night-vision (scotopic vision)
C: precise vision of contours and colours
D: good night-vision after adaptation to darkness (30 min)









Answer: D



Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. Cone cells are densely packed in the fovea, but gradually become sparser towards the periphery of the retina. Rods are concentrated at the outer edges of the retina and are used in peripheral vision.”

This is why, in dark circumstances you can focus on something more easily by looking directly next to the object.

What is the approximate Time of Useful Consciousness for a seated pilot following a rapid decompression at 35,000 ft ?

A: 45 seconds
B: 12 seconds
C: 5 minutes
D: 3 seconds









Answer: A

Altitude in FL Time of Useful Consciousness
FL 150 30 min or more
FL 180 20 to 30 min
FL 220 5-10 min
FL 250 3 to 6 min
FL 280 2.5 to 3 mins
FL 300 1 to 3 mins
FL 350 30 sec to 60 sec
FL 400 15 to 20 sec
FL 430 9 to 15 sec
FL 500 and above 6 to 9 sec

Flying immediately following a dive with SCUBA diving equipment to a depth greater than 10 metres is not advisable because:

A: will always lead to hypoxia
B: prevents any dangers caused by DCS (decompression sickness) when climbing to altitudes not exceeding 30 000 FT
C: has no influence on altitude flights
D: can cause decompression sickness even when flying at pressure altitudes below 18 000 FT






Answer: D

What are the main sources of radiation at height?

A: Galactic (Cosmic) and Nuclear radiation which are both caused by the earth’s natural radiation.
B: Ionisation of the layers in the atmosphere due to the bombardment of Galactic (Cosmic) radiation.
C: Solar radiation caused by solar flares and Nuclear radiation caused by the earth’s natural radiation.
D: Galactic (Cosmic) caused by galactic particles and Solar radiation caused by solar flares.









Answer: D