Human Performance & Limitations - Hearing & Vision

Question 1

Perfect vision (6/6 or 20/20) is limited to the most central part of the retina which contains only ‘cones’. What is the most central part of the retina called?

Answer 1

The fovea

Question 2

True or Flase - ‘Binocular Vision’ allows us to judge distances and also compensate for the fact that each eye has a ‘blind spot’.

Answer 2

True

Question 3

What is the smallest object that can be ‘seen’ (under conditions of better than 20km visibility by a person with 6/6 (20/20) eyesight) at a distance of 16km (10NM)?

Answer 3

3m in diameter

Question 4

Why are powerlines so hard to see from a distance?

Answer 4

Because of their relatively small diameter

Question 5

List 2 flying conditions that constitue an ‘empty’ sky whereby the eyes have nothing to focus on in the distance

Answer 5

Any of the following:

• flight over water,
• flight in thick haze where the
  horizon is obscured,
• flight over a haze or cloud
  cover layer with high overcast
  cloud layer above

Question 5

To overcome the problem of short focal distance in ‘empty’ sky conditions (empty sky myopia) - should pilots repeatedly re-focus on the closest or most distant object that can be seen?

Answer 5

Most distant

Question 6

Outside a 10deg cone (concentric to the foveal 1deg cone), can you only see approximately 10% or 90% of what you can see in the foveal cone?

Answer 6

10%

Question 7

Visual fatigue can lead to impaired vision. What are 4 symptoms of visual fatigue?

Answer 7

Blurred vision,

Excessive tear production,

‘Heavy’ eyelid sensation,

Headaches,

‘Burning’, ‘scratchy’ or dry eyes

Question 8

What atmospehric condition tends to make aircraft look further away than they acually are?

Answer 8

Haze

Question 9

Why can taking off and landing into the sun be dangerous?

Answer 9

It may cause temporary blindness

Question 10

What is the ventilation passage which connects the middle ear to the back of the nose called?

Answer 10

Eustachian tube

Question 11

What part of the ear are the cochlea and vestibular apparatus located within?

Answer 11

Inner ear

Question 12

What function is the cochlea and the vestibular apparatus responsible for?

Answer 12

Cochlea - hearing

Vestibular apparatus - balance

Question 13

The eardrum, in order to function properly, must have equal pressure on either side so that it can ‘vibrate’ freely and allow us to hear. What structure is reponsible for equalising the pressure?

Answer 13

Eustachian tube

Question 14

Are the semicircular canals and otoliths part of the hearing mechanism or vestibular system?

Answer 14

Vestibular system (balance)