Ch 12 - Perception And Perceptual Errors Flashcards
Perception
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
2 Stages of perception:
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
Gestalt - 5 Laws of Perception
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
Visual Constancy
Perceive an object as being unchanged despite changes in the surrounding environment
Size Constancy
Perceive that an actual objects size remains the same, even when the object through the retina is changing size
Shape Constancy
When objects are at different angles, we perceive them as being the same object
Colour and Brightness Constancy
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
Perceptual Set and Expectancy
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)
Physiological Limitations of Perception
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
3 Categories of Illusion (most common)
Visual
Auditory
Kinaesthetic
Visual Illusion of Comparative Size
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
Visual Illusion of Perspective
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
Auto-Kinetic Illusion (Autokinesis)
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
Taxiing Illusions
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.
TakeOff and Missed Approach Illusions
Somatogravic Illusion - feel like you are flying with a steeper angle than you are
Can be fatal (FlyDubai)
False Horizons
Surface lights or fishing boat lights being confused as stars and causing accidents
Gently Sloped Terrain or Bank of Cloud
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
Cruise Illusions
Vertical separation
AC coming towards you end up going beneath
Mountain or terrain appears smaller when you get closer to it
Holding Illusions
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
Approach and Landing Lights
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
Landing Visual Aiming Point
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
Landing Illusion: Visibility
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
Landing Illusion: Runway Width
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
Landing Illusion: Runway Slope
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
Landing Illusion: Black Hole Effect
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
Landing Illusion: Rain on Windscreen (angle of approach)
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
Landing Illusion: Rain on windscreen (speed)
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
Height Judgement
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)
Mid-Air Collisions
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)
To Protect yourself From Illusions
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!!!!
