Chapter

10

Cognition in Aviation

Cognition in Aviation . . . . . . . . . . . . . . . .	. . . . . .	. .	. .		.183
Visual Illusions					183
An Illusion of Movement . . . . . . . . . . . . . .	. . . . . .	. .	. .	.	185
Other Sources of Illusions					186
Illusions When Taxiing . . . . . . . . . . . . . . .	. . . . . .	. .	. .	.	186
Illusions on Take-off					187
Illusions in the Cruise . . . . . . . . . . . . . . . .	. . . . . .	. .	. .		.188
Approach and Landing					189
Initial Judgement of Appropriate Glideslope . . . . . . .	. . . . . .	. .	. .	.	189
Maintenance of the Glideslope . . . . . . . . . . . .	. . . . . .	. .	. .		.191
Ground Proximity Judgements					192
Missed Approach - Somatogravic Illusion . . . . . . . .	. . . . . .	. .	. .	.	192
Protective Measures against Illusions . . . . . . . . . .	. . . . . .	. .	. .		.193
Collision and the Retinal Image . . . . . . . . . . . .	. . . . . .	. .	. .		.194
Human Performance Cognition in Aviation					195
Special Situations . . . . . . . . . . . . . . . . .	. . . . . .	. .	. .	.	196
Spatial Orientation in Flight and the “Seat-of-the-pants” . .	. . . . . .	. .	. .	.	197
Oculogravic and Oculogyral Illusions . . . . . . . . . .	. . . . . .	. .	. .		.198
Questions . . . . . . . . . . . . . . . . . . . .	. . . . . .	. .	. .		.199
Answers . . . . . . . . . . . . . . . . . . . .	. . . . . .	. .	. .	.	202

181

10 Cognition in Aviation

Aviation in Cognition 10

182

Cognition in Aviation 10

Cognition in Aviation

Introduction

Human beings have evolved to function at sea level and at speeds achievable on two legs. Flight puts the pilot into an environment which can distort sense organs. In addition the changed perspective experienced in flight can result in information being presented which is outside the individual’s expectations.

Illusions - General

We use mental models as frameworks to make sense of the world and guide our actions. Mental models can be incomplete and thus faulty. In aviation the mismatch between what we sense and what we expect is an illusion. In other words the difference between perception and reality.

Objects seen from the air look quite different than when viewed on the ground. Because of the lack of stable visual references and the erroneous mental models that may be produced, the pilot is at a disadvantage. In addition, in flight, the pilot’s cognitive and sensory orientation mechanisms have to try and cope with a third dimension to which they have not been designed. This will lead to both mental and physical illusions.

Illusions may occur during all stages of the flight and to pilots of every experience and skill level. The pilot, therefore, should be aware of the possibility of misinterpreting the information received. Illusions can affect all of our senses but those of particular concern in aviation are those which affect our visual sense and those affecting the balance organs in the middle ear. We also possess a position sensing system derived from nerve endings in the skin, muscles and joints which can be a source of incorrect information passed to the brain.

Visual illusions are particularly dangerous in aviation as we normally consider our visual input to be the most reliable of our senses.

Visual Illusions

A	B
C
	D

Figure 10.1 Some geometrical illusions

Cognition in Aviation 10

183

10 Cognition in Aviation

Aviation in Cognition 10

Most people are familiar with the two dimensional figures in Figure 10.1.

In A the figure with the out-going fins appears to contain a longer line than the other, although both are exactly the same length. We are not often going to see large finned lines on our airfields but the natural scenery, the junction of two roads or railways, the alignment of valleys, even a small runway running into the corner of a field where hedges meet can give a false impression of runway length.

In B the upper of the two horizontal lines appears the longer, but they are the same size.

In C the vertical straight lines appear curved, but they are straight.

In D which line passes through the two vertical parallel lines? Try it with a straight edge.

Other visual illusions involve a perceived depth appreciation.

Both of the illustrations in Figure 10.2 and Figure 10.3 can obviously be visualised as a model but neither could exist in real life.

Figure 10.2 Illusion in depth

Figure 10.3 Concave & convex

184