Ch 12 - Perception And Perceptual Errors

Question 1

Perception

Answer 1

Based off past experience and knowledge (previous and learnt)

“We can perceive only that which we can conceive”

When perception matches reality, we are Situationally Aware

Question 2

2 Stages of perception:

Answer 2

Bottom Up; given to us through our senses (CNS -> brain)

Top Down; to perceive based off knowledge and past experience

In reality we are doing both; Interactive Processing

Question 3

Gestalt - 5 Laws of Perception

Answer 3

The whole is greater than the sum of its parts

1 - Continuity - objects that form a continuous form are perceived to be together or in the same group

2- Periodicity - fill in the gaps

3 - Proximity - closer together, we see as part of the same group

4 - Similarity - Objects similar in appearance appear as part of the same group

5 - Symmetry (simplicity) - no matter the distance apart, if symmetrical, we perceive as being part of the same group

Question 4

Visual Constancy

Answer 4

Perceive an object as being unchanged despite changes in the surrounding environment

Question 5

Size Constancy

Answer 5

Perceive that an actual objects size remains the same, even when the object through the retina is changing size

Question 6

Shape Constancy

Answer 6

When objects are at different angles, we perceive them as being the same object

Question 7

Colour and Brightness Constancy

Answer 7

Tendency to perceive as object as maintaining it’s level of brightness in relation to its surroundings, despite different levels of light coming through the retina

Question 8

Perceptual Set and Expectancy

Answer 8

The predisposition/readiness to perceive particular features in a certain way.

Works in two ways; selecting relevant information or interpreting actual information

Not easy to change your perceptual set, audibly and visually and it can be very dangerous

Press-on-itis and get-home-itis can cause problems (747 crash)

Question 9

Physiological Limitations of Perception

Answer 9

Vision is not our most reliable sense!!!!

Can often be a mismatch between visual and vestibular system which can lead to illusions and then perceptual errors

Question 10

3 Categories of Illusion (most common)

Answer 10

Visual

Auditory

Kinaesthetic

Question 11

Visual Illusion of Comparative Size

Answer 11

Pine trees example

When you expect an object to be of a certain size but in reality it may be smaller or larger - separation clearance may be effected

Question 12

Visual Illusion of Perspective

Answer 12

When we expect things to be of a certain way or shape, we then perceive them in that way when in reality it could be totally different

Question 13

Auto-Kinetic Illusion (Autokinesis)

Answer 13

Night flying with a light in the distance with no visual background, can cause the light to appear as if it is moving.

Caused by the saccades within our eyes.

Danger - people have confused stars as being ac lights or fishing boats being stars

Question 14

Taxiing Illusions

Answer 14

Depends on your relative motion to the ground and the heigh above it. Can make you think you are taxing too fast or too slow.

Question 15

TakeOff and Missed Approach Illusions

Answer 15

Somatogravic Illusion - feel like you are flying with a steeper angle than you are

Can be fatal (FlyDubai)

Question 16

False Horizons

Answer 16

Surface lights or fishing boat lights being confused as stars and causing accidents

Question 17

Gently Sloped Terrain or Bank of Cloud

Answer 17

If flying visually, you will fly using the gradient of the land (false attitude) putting you into nose down or nose up /side causing you to potentially be higher or lower than you think

RELY ON INSTRUMENTS

Question 18

Cruise Illusions

Answer 18

Vertical separation

AC coming towards you end up going beneath

Mountain or terrain appears smaller when you get closer to it

Question 19

Holding Illusions

Answer 19

When you are going round and round and round, can lead to;

Somatogyral Illusion - think you have banked over in the opposite direction when returning S&L

Corioless - Stimulating 1 or more of your vestibular apparatus

Vertigo - Dizziness or tumbling sensation

JUST KEEP YOUR HEAD STILL AND BREATHE

Question 20

Approach and Landing Lights

Answer 20

PAPIs and VASIs

All red - too low
3 Red - slightly low 
2 R 2 W - Approach character 
3 white - slightly high
4 white - too high

Visual texture flow helps with final height and speed judgement

Question 21

Landing Visual Aiming Point

Answer 21

Should be looking to touchdown just after the threshold lines (piano keys)

Keep your visual aiming point slightly in front of touchdown point as the AC could bear very long

Keep looking at same point on the approach

Question 22

Landing Illusion: Visibility

Answer 22

Poor visibility (Haze, fog, cloud) makes the RW seem further away than it actually is

You then think you are too low

Pitch Up

Leads to a too steep approach and possible overshoot

Question 23

Landing Illusion: Runway Width

Answer 23

Narrower RW

• Illusion of being too height
• Think you are too high
• Pitch down to correct
• Leads to a shallow approach and possible undershoot

Wider RW

• Illusion of being too low
• Think you are too low
• Pitch up to correct
• Leads to a very steep approach, early roll out/round out/ flare possible

Question 24

Landing Illusion: Runway Slope

Answer 24

Downward sloping runway

• Think you are too low, RW seems longer / bigger
• Pitch up to correct
• Overshoot, steep approach and early flare possible

RW sloping up

• Think you are too high, RW seems shorter / smaller
• Pitch down to correct
• Undershoot possible

Question 25

Landing Illusion: Black Hole Effect

Answer 25

Caused by flying at night time over featureless terrain (desert/ocean) with no visual reference

Makes you think you are closer to the RW than you are, think that you are too high

So you pitch down to correct

Which leads to a shallow approach, possible undershoot

Question 26

Landing Illusion: Rain on Windscreen (angle of approach)

Answer 26

This is possible day and night

The rain on the windscreen has a magnifying effect which makes you think you are too high (RW drops beneath you)

This makes you pitch down to correct

Leads to a low shallow approach with a possible undershoot

Question 27

Landing Illusion: Rain on windscreen (speed)

Answer 27

In the day:

• You think you are further away than you actually are so you think you are flying slower than you actually are
• Thrust / power increased to correct
• Leads to a possible overspeed/ too higher approach speed

In the night:

• The RW lights appear brighter which makes you think that the RW is closer than it actually is and that you are approaching too fast
• Power/thrust reduced to slow you down
• This decreases the speed and could lead to a potential stall

Question 28

Height Judgement

Answer 28

Over very smooth surfaces with no details, you think you are higher than you are

This can cause you to pitch down potentially to a point where you are far too low

Could be dangerous for clearance

White out can also give us the same illusion (snow)

Question 29

Mid-Air Collisions

Answer 29

Same relative bearing, travelling at the same speed

You perception will not pick up the relative motion which makes it very hard to spot

The eye saccades when resting then pick up the AC when it is getting closer, but only in bits.

Starts very small but very quickly will be much bigger and closer (DHL and Russian flight)

Question 30

To Protect yourself From Illusions

Answer 30

Before flight make sure you are planning well, you know what is supposed to be happening, you train well

During the flight, make sure you are scanning, checking your instruments and believing your instruments!!!!