The Aviation-Colour-Perception-Standard
Produced by Arthur Pape and
proudly sponsored by: AOPA
Australia,
whose mission it is to
promote the „Freedom to Fly Responsibly” – Philosophy of Aviation Regulation.
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Contents |
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(2) About the Author |
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(4) The Fundamentals |
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(14) Summary |
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CAUTION!! This
page is colour coded. Only those with normal or „defective safe“ colour vision
may use it.
In fact, the
rationale of the use of colour in this web page is about as sophisticated as
the use of colour in the aviation environment, and just as unsystematic. However,
all will agree that the use of colour makes the page more pleasing to the eye,
a benefit that applies to all grades of defective colour vision as well as to
the colour normal reader.
This page is dedicated to the millions of youngsters
the world over whose ambitions to become pilots and enjoy the immense delights
of aviation are thwarted by the colour perception standard.
We hope to instil hope for those frustrated
by this „standard“ which is based on unscientific nonsense and promoted by a
small but vocal band of blinkered vision „specialists“. These people understand
little about either aviation or the miracle of perception.
Nowhere has the debate been more intense
than in Australia, where for twenty years the author has fought against the
standard. In the late ‘eighties, the battle culminated in two landmark appeals
to The Administrative Appeals Tribunal which resulted in the removal of
restrictions on night flying for all Australian pilots with colour vision
defects. The tribunal found after exhaustive examination of all the issues that
colour vision defects do not constitute a risk to the safety of air navigation.
This web site will expose in detail why the
Aviation Colour Perception Standard is simply wrong and unnecessary. It is
intended to educate both those with normal colour vision and those with
defective colour vision. It is hoped too that those charged with the
responsibility for aero-medical standards will take the time to consider the
arguments promoted here. There is no place in the regulating of the safety
standards of aviation (or for that matter in any sphere of human activity) for
anything based on bad science or ignorance.
My name is Arthur Pape. I am a Dutch-born Australian and graduated in
Medicine in Melbourne, Australia in 1969. My flying career began in 1977, and I
have gained the Australian Commercial Pilot Licence with Command Instrument
Rating for Multi-engine aircraft. At time of writing I have approximately 1500
hours total aeronautical experience. I am a Designated Aviation Medical
Examiner for the Australian Civil Aviation Safety Authority, and the
Vice-President of AOPA Australia. My hometown is Geelong, Victoria, Australia
where I have my own general practice. My aircraft is a much-loved 1976 Seneca
II. I believe it is probably the record holder for nose gear failures: four in
six years, but that is another story altogether.
I have defective colour vision.
In 1977 I started my inquiries into the aviation colour perception
standard. When first licensed, I was prohibited from flying aircraft at night
because of my colour vision deficiency. The reason given was that aircraft were
fitted with coloured navigation lights that assisted pilots in determining
collision risk, and that therefore individuals who could not reliably identify
those lights represented a risk that justified their exclusion from the
activity. Later, many more reasons were added, which are explained elsewhere on
this site.
In due course I had opportunities to observe all of these uses of colour
in aviation and I became aware of a disparity between what I knew I could
perceive and what I was told I shouldn’t be able to see. The colour perception standard
became a major focus of mine from then on. What was it and what was it designed
to achieve? On what scientific foundation was it built? Were there experiments
or scientific studies that gave the standard scientific validity? These and
many more questions occupied me for some ten years. All the while my knowledge
of and experience in aviation was growing. I had access to sophisticated
simulators where I was able to use the wonderful EFIS equipment of the B767. I
flew in the real thing observing everything from the „jump seat“. I knew what
the pilots were required to derive from this equipment and I had no trouble in
deriving the same and in exactly the same manner.
Simultaneously, I read the „scientific“ stuff by the box full. The
contradiction between the theory on which the colour perception standard was
based and my personal observations and understanding grew ever wider.
My observations of other aircraft and lit obstructions in the night
flying environment, of runways and taxi ways, of thresholds and holding points,
of tower signal guns and of all of the matters that were supposed to be a
problem to me but weren’t, further reinforced my growing suspicion that my
colour vision defect was likely irrelevant. But the conviction was still
largely intuitive.
A major turning point came to me fortuitously when I met the then newly
appointed Professor of Psychology at Deakin University, Professor Boris
Crassini. He listened patiently to my concerns about the standard and about the
scientific projects that were claimed to validate the standard. Boris is a
perception scientist, with his major interest visual perception. He was able to
confirm most of my suspicions and in due course he became a major inspiration.
Through him and his colleague, Dr. Patrick Flanagan, I have come to understand
much about perception and about the philosophy of science. But perhaps the most
valuable lesson he gave me was to accept the fact I was a colour defective and
to stop claiming I could „see the colours“. This acceptance was an essential
pre-requisite to the conduct of the appeals that were to follow. Boris’ and
Patrick’s expert testimony before the Tribunal was rational, unbiased,
flawless. Colour defectives in this country owe them.
With growing confidence, I repeatedly put my viewpoint to the Australian
regulators, to be met only with growing hostility. When all attempts at such
reasoning were exhausted, I took the matter to the courts. I was responsible
for two appeals, both of which were upheld. I felt vindicated.
But the colour perception standard has powerful supporters who will
never accept the umpire’s verdict. Some eight years after the Denison decision,
they continue to ignore it. They continue to denigrate the Tribunal’s decision,
claiming it to have been beyond the jurisdiction, beyond the competence of the
Tribunal. Egos and reputations suffered. The „knight in shining armour“ expert
is, even today, being sought who will set the records straight and restore the
standard to its rightful lofty position.
What they can’t bring themselves to do is to recognize why they
lost the cases: the aviation colour perception standard is founded on bad
science and bad logic. Not that the protectors of the standard are bad or
dishonest but that their theory and scientific validation thereof is flawed and
doesn’t withstand critical scrutiny.
A Brief History of the Standard
Many years ago people with defective colour vision were barred from
flying aeroplanes. The reason was that „colour“ was „used“ in aviation to
signal matters of importance. Radio had not been invented. Aircraft were fitted
with „navigation lights“ just like the ships of the sea. Permission (clearance)
to land, takeoff, taxi on the airfield were transmitted by the use of coloured
flags or lights and colour defectives were demonstrably unreliable in
interpreting such coloured signals. The navigation light system (red on port,
green on starboard and white on stern, even the terms were those of ships) was
believed to assist collision avoidance. What a catastrophe it would be if the
failure to see the colours caused a mid-air collision. And so it was the the
aviation world came to impose the Colour Perception Standard. The Paris Peace
Conference of 1918, following WW1, was the forum that formerly introduced it.
Since that era, aviation has grown to be a sophisticated and commonplace
mode of public transport. Over the years radio communication and navigation
developed to ever greater reliability and usage. Aircraft grew larger and
speedier. Colour was added to the „system“, not by careful design but by
haphazard additions, „because it was there“. The list of „uses“ of colour in
aviation is now extensive indeed.
And as the aviation system was growing and maturing, so was the
scientific understanding of vision, including knowledge of the basis of
defective colour vision, and so was scientific understanding of perception.
Specialties developed in Ophthalmology, Optometry and Perception Psychology,
the „vision sciences“.
But still the Colour Perception Standard remained. Sure, some countries
made concessions in the face of growing uncertainty over its relevance. In time
no-one seriously argued that the navigation light system could contribute to
collision avoidance. The perception of collision risk in aviation cannot be
„colour coded“ any more than in tennis or football. And the use of coloured
signal lights from ground to air fell into disuse because of sophisticated and
universal use of radio. The Colour Perception Standard, in the early seventies
looked to be ready for retirement.
There had been a staunch band of supporters of the standard ( I call
them the „Protectors of the Standard“ ), whose industry relied to some extent
on the provision of colour vision testing, who needed to find a new „raison
d’être“ for the continuance of the standard, and the introduction of CRT-based
cockpit instrumentation was just the item needed. Here was a new generation of
sophisticated equipment, in which colour could be „used“ almost without limit.
What a saviour, and just in the „nick of time“. The Colour Perception Standard
could, it was supposed, be defended once more.
The defence of the standard needed to be based on „scientific evidence“
that colour defectives would be at a disadvantage in the use of this new
technology, and therefore the exclusion of these individuals would be in the
interest of „the safety of air navigation“. Yes, it had to be all about safety.
Not pleasure, comfort, equal opportunity or civil rights, but safety.
Meanwhile though, colour defectives in growing numbers had joined the
aviation pilot community. They hadn’t experienced any of the disadvantages that
the theorists had predicted. They did everything that pilots are required to
do, and no-one noticed they were colour defective. They came to fly at night in
growing numbers and they found themselves commanding aircraft with all the new
technologies. Their colour defectiveness was irrelevant. By the standards upon
which pilots are measured, the colour defective pilot’s performance could not
be distinguished from that of their colour normal colleagues. Their political
experiences varied from one country to another. In the USA, the standard had
„degenerated“ to such an extent that colour defectives were able to find
employment in major airlines and become captains of the latest jet airliners.
They could fly their jets into other countries where stricter colour perception
standards would have excluded them from being even the private pilot of a tiny
Cessna.
In Australia, the aviation authorities struggled to understand the
issues and to implement a standard that could be defended in the courts, where
they were coming under increasing pressure to validate the standard with
scientific evidence that it was relevant. With the advent of the Electronic
Flight Instrumentation Systems (CRT-based cockpit displays), the opportunity
was seized to conduct research that would demonstrate that colour defectives
were less accurate and slower in the interpretation of the information
displayed on EFIS equipment. The Standard would thus be „protected“.
The Aviation Colour Perception Standard is now once more in the
spotlight, both in Australia and at international level. This year national
representatives to ICAO are conducting a series of meetings to review the
standard. The prospect of a stable and rational international standard being
adopted are remote. The USA, Canada and Australia are so far down the path of
liberalization that to turn back would be politically untenable. Representatives
of the European Joint Aviation Authority, on the other hand, are lobbying for
the strictest of colour perception standards. Of interest to me is that the
arguments haven’t changed. They continue to rely for scientific validation on
the works of the likes of Cole and Macdonald.
The Protectors of this standard are still extremely active. There is
much at stake for them.
1. Any regulations that seek to prohibit
the participation of individuals in a lawful pursuit or occupation must be
based on scientific evidence that is of the highest integrity. Such scientific
evidence must have been subjected to the most intense and comprehensive critical
analysis before being converted into binding and discriminatory law.
2. The enforcement of such regulations
based on anything less constitutes discrimination no less repugnant than
discrimination based on race, religion or sex.
3. The Aviation Colour Perception
Standard is one such regulatory instrument, for which the scientific basis is
deficient and flawed.
The „Protectors” of the Standard
The Australian debate on the Aviation Colour Perception Standard has
seen a virtual monopoly on the „pro-standard“ side held by the academic
optometry profession. The Victorian College of Optometry, at the University of
Melbourne, has had, it would appear, exclusive rights to the research dollars
from the aviation authorities when it comes to vision research. The long-time
head of that college, Professor Barry Cole, is well known from his publications
in support of stringent colour perception standards, not only in aviation but
in all forms of transport, as well as a host of other professions. It was his
evidence that invariably led to the failure of appellants in the courts to
obtain relief from the restrictions that the colour perception standard
mandated. The dossier of communications (obtained under the Freedom of
Information) between the professor and the Director(s) of Aviation Medicine
over a period of ten years reveals the prime intent of the research to be to
„Protect the Standard“. Never was a conflict of interest more likely. Not until
the Pape and Denison cases referred to in this document, did the scientific
basis of the standard come under serious analysis, at least in this country.
The works and views of Barry Cole were severely tested under rigorous
examination and cross-examination.
The May 1989 issue of „Australian Optometry“ had front page coverage of
the decision in the Denison case. It reported accurately the Tribunal’s
decision. Yet as recently as June 1997, the official careers advisory of the
Australian Optometrical Association persists in promoting the false advice that
colour defectives should not consider careers in aviation, despite the sweeping
changes that the Tribunal’s decision in Denison had forced on the Australian
Civil Aviation Authority.
Textbooks of Optometry from around the globe continue to promote the
same nonsense.
Dr Barry Clark’s (himself a Ph.D. in Optometry and colleague of Prof. Barry
Cole) recent article in Avmedia, the Journal of the Aviation Medical Society of
Australia and New Zealand, makes the most fleeting and inaccurate reference to
the Denison AAT case. As stated elsewhere, the line of approach of these people
is always to avoid detailed analysis of the uses of colour, preferring to argue
in generalities whose logic, they might hope, will be self-evident to the
readers.
It is plain that despite the comprehensive rejection of their views by
the Australian Administrative Appeals Tribunal (which is a branch of the
Australian Federal Court) they have learnt nothing from their involvement in
the process.
All regulators who seek to rely on scientific „proofs“ to validate
discriminatory laws should exercise the most meticulous and critical
scrutiny of the research methodology employed.
Defective Colour
Vision: What is it?
The physiology and genetic transmission of defective colour vision is
not a contentious issue and will therefore be covered here in only a summary
manner.
Normal colour vision involves the activity of three pigments that reside
in the cone cells of the retina of the eye. One pigment is maximally responsive
to light at the red end of the spectrum, the next to light in the green region
and the third to light at the blue end of the visible spectrum. When one of the
pigments is either partially or totally dysfunctional, abnormal colour „
“perception results. „Protan“
dysfunction results from reduced red pigment function (Protanomalous = partial
dysfunction, Protanope = total red pigment dysfunction ). Green pigment
dysfunction results in „Deutan“ disorders (Deuteranomaly = partial,
deuteranopia = total green dysfunction). Blue pigment dysfunction results in
the „Tritan“ disorders of Tritanomaly and Tritanopia.
The heredity of the Protan and Deutan groups is X-chromosome mediated
and the Tritan group is autosomally transmitted. Together, the Deutan and
Protan groups account for almost ten percent of the male population and just
under one percent for the female population. There may be some variation in the
incidence between races. the Tritan group is much rarer and is not detected by
standard colour vision testing.
Readers interested in further explanation of the inheritance and
physiology of defective colour vision should refer to definitive vision
textbooks or encyclopaedias on the subject..
What Can’t Colour Defectives Do?
Colour defectives have, as a result of the dysfunctional colour receptive pigment in their cones, diminished ability to discriminate between colours. Colour (or „Hue“) is that property of light determined by its wavelength. Whereas colour normals may discriminate between many colours ( perhaps thousands), colour defectives are able to discriminate between many less. Colour vision testing procedures rely on this reduced discrimination ability to detect and grade the dysfunction.
It follows therefore that colour defectives cannot pass colour vision tests. This includes tests which rely on pattern recognition where elements of the pattern are constructed from dots whose colours are taken from the „confusion zones“ for colour defectives that can be calculated on chromaticity charts. The Ishihara test for colour vision is the best known and most widely used test of this kind. There are many other sophisticated tests for colour defective vision and the scientific basis of those tests is well established. Colour defectives are „wavelength cripples“. But they are not „colour blind“.
It follows also that colour defectives cannot reliably identify and name colours as well as the colour normal does.
Finally, it follows that colour defectives cannot as easily as colour normals extract information from systems where wavelength coding is used to non-redundantly encode information. Much rests on this particular point when we examine the use of so-called „colour coding“ in aviation systems.
What Can Colour
Defectives Do?
Apart from the reduced ability to identify
and name colours and to discriminate between colours, passing colour vision tests
and extracting information from non-redundantly wavelength coded systems, colour
defectives can do everything else. Simple as that!
THE DISABILITY
OF DEFECTIVE COLOUR PERCEPTION IS CONFINED TO REDUCED SENSITIVITY TO THAT
PROPERTY OF LIGHT DEFINED BY ITS WAVELENGTH
Colour defectives have the same capacities as colour normals to perceive
form, motion, depth, luminance contrast, and so on.
They have the same capacities as colour normals for complex
perceptual-motor skills that form a part of the myriad activities of daily
living, playing sports, motion in three dimensional space, and flying
aeroplanes.
That colour defectives can fly aeroplanes is self evident. There are
many thousands doing so in the United States and in Australia.
Furthermore:
„Scientific“ Evidence or „Sleight of Hand“?
The Aviation Colour Perception Standard is based on a tenuous thread of
logic that may be summarized thus:
1. Colour is used extensively („ubiquitously“!) in the aviation
environment, both inside and outside the cockpit, to codeimportantinformation.
2. The use of colour enhances the performance (in both speed and
accuracy) of tasks and object recognition for colour normal observers.
3. Colour-defectives are less able than colour normal users to use the
colour-coded information as reliably or as speedily.
4. Restricting the benefits derived by colour normals from the use of colour
coding, in order to accommodate colour-defectives is not an attractive or
practical proposition.
5. Colour-defectives should therefore be screened out of the user
population by rigorous colour vision screening and testing.
6. The Aviation Colour Perception Standard should thus be vigorously
maintained.
The „protectors“ of the standard, without fail, avoid addressing the
specific questions that stem from the above broad proposition:
1. For each instance in the long list of colour
usage in the aviation
industry, WHAT INFORMATION IS IT THE PILOT IS EXPECTED TO EXTRACT AND
INCORPORATE INTO THE FORMULATION OF APPROPRIATE RESPONSES OR BEHAVIOUR?
2. In each case, DOES WAVELENGTH CODING ENHANCE THE ACQUISITION OF
THAT INFORMATION REQUIRED BY THE PILOT? IF SO, HOW?
3. If the answer to (2) above is affirmative for any instance , IS
THE COLOUR DEFECTIVE PILOT DISADVANTAGED BY VIRTUE OF THE DEFECTIVE COLOUR
VISION?
„Research“ by or on behalf of the „protectors of the standard“
invariably incorporates the following strategy:
1. Use naïve subjects who will undergo a brief tutorial on the technical
terms (NEVER USE EXPERIENCED PILOTS!)
2. Set tasks that are operationally (from a pilot’s point of view)
simplistic or irrelevant
3. Convert the test equipment into a DE-FACTO COLOUR PERCEPTION TEST
4. Selectively analyze the data to provide the desired result
The Cole and Macdonald papers are a prime example of this
technique, and may be summarized thus:
In phase (1), two groups of optometry students were used to determine
whether the use of colour in EFIS displays enhanced speed and accuracy of
information retrieval. One group was exposed to coloured displays, the other to
black and white renditions of the displays. The tasks were not ones that pilots
would perform. They were puzzles. ECOLOGICAL VALIDITY was absent.
In phase (2), various groups of colour defective observers, drawn from
the college’s patient lists, were subjected to the same puzzles, but only on
the coloured displays, and their response times compared with those of the
colour normal group who had been tested on the coloured displays. A token
gesture was made to adjust response times for differences in age, sex and
educational levels between the colour defectives and the colour normal students.
The mean age for the colour defective groups were significantly higher than
that of the colour normals. No attempt was made to properly match the colour
normal and colour defective test subjects for these crucially important
factors.
The response times were measured in terms of milliseconds. The
researchers had never travelled in the jump seat of a B767 (whose
instrumentation was used) to observe how pilots use the equipment. They betray
no hint of understanding the thorough checking and rechecking process that is
so much a part of safe and competent piloting.
The conclusions drawn were that colour use enhances accuracy and response
times for colour normal observers, but that the degree of this enhancement
decreased with increasing complexity or clutter of the display. It is
significant that the colour defective group was not tested on the black and
white displays to determine if they might also benefit from the use of colour.
Predictably, colour defectives made more errors and longer response times, but
because of the failure to match the groups for age, sex and educational level
attained, the conclusion that the variable of colour vision was responsible for
the difference in these results could not properly be drawn. The observation
that on at least one task the protan groups performed unexpectedly as well as
the colour normal group raised no suspicion as to the theory being tested.
This research project received very close attention from the AAT in the Denison
case and was rejected by the tribunal for the reasons stated above, and rightly
so. There is simply no scientific equivalent of the rigors of the court room,
where examination and cross-examination put the proponents of theories to the
ultimate test. Such was the case with this project and it fared very badly.
Yet this project is still quoted in the debate, even today, as
demonstrating that: „Colour vision deficients are slower than colour normals at
responding to redundantly colour-coded EFIS displays, and they make more
errors. Protanopes are especially disadvantaged in responding to red ‘fail’
messages“. Make no mistake, the research demonstrated no such thing.
Fundamental principles governing the conduct of research were not
adhered to in this project. It is not for me to advance this observation
further, but simply to point out that the claimed results are therefore totally
unsupported.
WHERE „SCIENCE“
IS USED AS A TOOL TO SUPPORT STANDARDS THAT, WITH THE FORCE OF LAW,
DISCRIMINATE AND TRUNCATE OPPORTUNITIES, THE ETHICAL RESPONSIBILITY OF THE
RESEARCHERS AND THE SPONSORS ALIKE IS ONE OF ENORMOUS MAGNITUDE.
What Pilots Do
and How They Do It.
Everyone knows pilots fly aeroplanes! Probably anyone can learn to do
it, but they need first to learn the basics of aerodynamics, navigation, power
plants, meteorology and the rules of the air. The level of learning increases
when higher licences are aimed for. Secondly they need to develop some
perceptual-motor skills that aren’t at all intuitive. These skills are learned
and rehearsed until they do become to a large extent automatic.
With increasing competence, demonstrated to appropriately qualified
examiners, the pilot will eventually find him or herself in a position of
command, where responsibility is assumed for the safe and successful outcome of
the flight.
From the moment of conception of a particular flight, the planning
starts, in anticipation of the conditions that might be encountered. Weather
briefings, the drafting of a flight plan, the calculation of fuel required, the
intermediate way points are proposed, and the intermediate and destination
landing points will be considered. The aircraft’s performance characteristics
will be studied. The more careful the pilot, the greater the degree of
preparation. Escape routes in the event of bad weather or other unforeseen
circumstances may be considered.
Before flight, the aircraft will be thoroughly checked for defects.
Engines will be ground run and performance checked against published criteria.
Control surfaces will be extended to their full range. Still on the ground, the
prevailing wind will be assessed and used to select a departure runway.
Passengers will be briefed on steps to evacuate in case of emergency. The pilot
will mentally rehearse the steps to be taken in the event of engine failure
during or shortly after takeoff. Checks, double checks and more checks. That is
the pattern. Good preparation indeed. The greater the familiarity with each and
all the factors that may affect the flight, the less the chance of being caught
unawares. IFR traffic in the area is mentally plotted even before takeoff.
Great stuff. Very professional! Hardly the stuff untrained college students can
learn in ten minutes, is it?
After takeoff, airborne, the pilot goes through the careful steps so
diligently learned in the training programme. After-takeoff checks, climb power
settings, and so forth. Practised, familiar, „second nature“. The aim is to get
to the destination enjoyably, safely, and economically. The protection of the
aircraft, passengers and crew is paramount.
To achieve this some fundamental tasks are to:
1. Not hit any other aircraft (collision avoidance)
2. Not hit any part of the ground or structures thereon, apart from in
the controlled landing manoeuvre (maintain obstruction clearance)
3. Keep a sharp lookout
4. Monitor performance of airframe, engine and navigation instruments.
All this and more is planned, rehearsed, studied. The flight involves
knowing from where you came and to where you are going.
When the unexpected does occur, the response, usually pre-considered,
needs to be careful and appropriate. Not at all like in the movies. Depending
on the nature of the unexpected condition, most will require careful
identification and corroboration with other indications. Check and cross check.
That’s how it’s done.
No room for knee jerk reactions, because they are almost always
inappropriate, and can lead to lethal consequences. Planning, anticipation,
identification, confirmation, check and more check and frequently. These are
the tools of the good pilot. In the end, action to correct the problem or avoid
the threat. Get the picture? Problem resolution requires action, but no action
to take place until the problem is unambiguously identified and confirmed.
(This scenario is a far cry from the experimental model that Cole and
Macdonald so impertinently used to „prove“ that colour defectives are slower
and make more errors in acquiring information from EFIS displays. What utter
naivety on their parts!)
The detection and avoidance of contact with other aircraft and fixed
obstacles is an important component of a successful flight. How are they
achieved? By day, in good visibility, luminance contrast against the background
and motion parallax are the indispensable clues to detection of collision risk.
What about by night? Well its exactly the same. The presence of lights on the aircraft
provide the luminance contrast and motion parallax the clue as to the risk of
collision. The brighter the lights, the easier the task of detection and
tracking. This, I invite the reader to consider, is so incredibly self evident.
By day or night in zero visibility (i.e. under the Instrument Flight Rules)
total reliance is placed on radio communication, radio navigation and such aids
as radar. But whether by day or night, whether in VFR or IFR, the mental or
visual „situational awareness“ is one of relative position (horizontal,
vertical and lateral) and relative motion (horizontally, vertically and
laterally) in the three dimensional medium that belongs solely to aviation.
The role of colour coding in assisting the pilot in determining the
distance to, the relative bearing in the three planes and the relative motion
of the target object is easily shown as being non existent. The role of the
coloured navigation lights as presence lights for the purpose of detection and
tracking is vastly inferior to the that of flashing beacons and strobes.
What about obstructions? Fixed obstructions are visible if they are lit
by night and simply invisible if they aren’t. The mere presence of a light
indicates the existence of an obstruction. Its distance and bearing cannot be
coded by wavelength of light (except in astronomy). Its just so simple. The
pilot should avoid contact with any lit object, and any object that has a fixed
relative bearing in all of the three planes will be hit. Do not fly under a
light unless you’re sure its another aeroplane (which is wavelength
independent) and avoid collision with any light by manoeuvring yourself to
increase the relative angular motion of the light in your field of view. It is
fundamental geometry, let alone a fundamental component of many activities that
involve complex perceptual-motor skills (driving, ball sports, contact sports,
taking a walk, grabbing a door knob).
Exactly the same geometry applies to achieving controlled contact with
ground in the process of landing the aeroplane, only the aim here is to
minimize the relative motion in the vertical and lateral planes to achieve a
stable approach. Relative bearing and relative motion are such fundamental
elements of practically everything we do in the way of locomotion, that like
the many learned skills, they come to be processed automatically. Certainly in
aviation, understanding of the concepts of relative bearing and motion, and of
vectors are central to almost every aspect of conduct of flight and navigation.
I won’t labour the point any further. Take a look at the list below,
kindly provided by Dr. Barry Clark, and think about each one, one at a time.
Ask what it is that colour might contribute to the task that confronts the
pilot: recognition and then responding appropriately to the information
derived. In each and every instance the presence of colour can be reliably
demonstrated to be superfluous to what it is the pilot is hoping to achieve. To
argue the case here for each instance of colour usage would extend me well
beyond the scope of this web page. But not so the AAT,
which took 28 days in the Denison case alone to work painfully through the
list, examination and cross-examination, to the point of exhaustion of all the
evidence. No wonder the „Protectors“ are upset. The whole campaign of
protecting the standard relied non-redundantly on detail avoidance.
Dr. Clark states that „colour coding is ubiquitous in aviation, with
many cases of functional colour coding“. In support of this broad
generalization, he provides an extensive list, which is quoted verbatim:
Significantly perhaps, he does not mention
the tower signal gun (Aldis Lantern), which employs red, green and white to
convey instructions to non-radio aircraft. This use of colour forms the basis
of the „practical test“ used in the USA to allow waivers against the standard.
Pilot Assessment and Licensing.
The process of becoming a pilot, as
outlined above, is one of learning the knowledge base and acquiring the
manipulative skills. In this regard it is little different from the acquiring
of a medical degree or becoming a plumber. Learning, training and assessment by
experts in the field are common to all. The experience of colour defective pilots
is no different. They follow exactly the same procedures and utilize exactly
the same clues for every aspect of the process. They are at no disadvantage,
and if the examiner were not told, there should be no indication that the pilot
he is examining is a colour defective. Such is my own personal experience and
that of the hundreds of colour defective pilots I have had contact with. They
do everything exactly the same way as their colour normal colleagues. They
cannot be told apart from their colour normal colleagues, unless and until they
are confronted with a colour perception test, either real or de-facto.
Remember, that is the one thing colour defectives can’t reliably perform.
Piloting an aircraft is not a colour perception test. It is a test in utilizing
knowledge and skills to guide a complex machine through three-dimensional space
and all that that entails.
The colour perception standard is supported
and imposed largely by bureaucrats and academics who have little appreciation
of the details of what pilots do and how they do it. They are bound to an
ideological theorem that does not withstand close scrutiny. After years of
being revered as an icon, an article of faith, the colour perception standard
now has to be „protected“ against the tide of colour defective pilots who
demand to be judged on their practical performance by people qualified to
assess their skills.
It is nothing short of shear arrogance on
the part of the „Protectors“ to claim their wisdom on this matter should carry
greater weight than the instructors and examiners of airmen on whose judgement
the „safety of air navigation“ truly depends. More so the arrogance when the
tide of public judgement, through the agency of the courts, turns to
recognition of the mythological nature of the standard.
I am a colour defective physician. The role
of colour coding in medicine is far greater than it has ever been in aviation.
Red flecks of blood in a brown stool are beyond my capabilities. Histology
could never be my forte, as it uses non-redundant colour coding to convey
important information. But in essence, the impediment of defective colour
vision has no significance to the way I practise my medicine. When in doubt on
a colour related matter, I ask a colleague or the patient. They love to help
this „wavelength cripple“. The inconvenience is trivial. I know my
limitations and I manage very well.
The
Administrative Appeals Tribunal
Australia is indeed a lucky country in many
respects. It is, in comparison to many others, an open and very democratic
country. The Administrative Appeals Tribunal is a branch of the Australian
Federal Court. Individuals who feel aggrieved by the decision of a regulator to
refuse a licence or to vary or cancel a licence may take the matter to the
Administrative Appeals Tribunal to have the decision reviewed independently.
The Administrative Appeals Tribunal is empowered to „stand in the shoes“ of the
decision-maker. Thus when an appeal is upheld, the Tribunal’s decision has the
force of law, just as if the original decision-maker had come to the same
decision.
There were three cases that the AAT
considered from 1985 to 1989. Links to the relevant decisions are provided.
The first case determined established that the
AAT did indeed have the power to hear the appeal, and set the scene for the
later two cases. The time gap was due to the fact that the costs of the cases
were borne largely by myself.
The second case involved the examination of
the substantive issues relating to the aviation colour perception standard. On
legal advice, the case was limited in aim to making any in-road against the restriction
on night flying that colour defective pilots were subjected to. In that aim it
was successful. However, the Department of Aviation refused to extend the
benefit of the decision to any pilot other than myself. Other petty
obstructions were placed by the severely „miffed“ authorities, but eventually
overruled by return to the AAT. This necessitated the conduct of a third and
comprehensive test case that would achieve, if successful, universal relief for
Australia’s colour defective pilots:
The third case, with the support of both
the applicant and the CAA, was conducted as a comprehensive review of all the
evidence pertaining to the Aviation Colour Perception Standard. By agreement,
the evidence submitted in the earlier case on the role of colour coding of
navigation lights was not repeated, but was transposed into the substance of
this hearing. Between the two cases, the total number of days devoted to the
submission of oral and written evidence was approximately forty. Not a single
instance of the use of colour in civil aviation was ignored. The evidence was
comprehensive and was subjected to intense and critical analysis. The Tribunal
performed its function with meticulous impartiality and thoroughness. It
performed what amounts to the most thorough and comprehensive examination of
the issue ever conducted anywhere on the globe to that point in time and since:
The result was a resounding rejection of the proposition that defective
colour perception poses any threat to the safety of air navigation
The evidence heard at the Administrative
Appeals Tribunal was comprehensive and focused on detailed analysis of what
pilots do and how they do it and what, if any, role colour played in the
process. It was the first time in the history of aviation the „problem“ of the
colour perception standard had been so meticulously put to independent
scrutiny.
The resultant liberalization of the
Australian version of the colour perception standard raised, and still raises
eyebrows within the global community of „protectors“ of the standard. Most
react without even having read the decisions and reasons. Responses have ranged
from „ignore it“, „denigrate it“, „do it again, and we’ll show ‘em“, and in
rare instances „let’s take a closer look at this“. The majority chose to ignore
it. But the process is unstoppable. The colour perception standard is based on
the myth that important information (for pilots) can be coded by wavelength
without the considerations of context, shape, size, position, luminance, all
these factors that by definition will render wavelegth information redundant
and superfluous. The piecemeal analysis of each and every instance of colour
usage is tiring and sometimes challenging. But that’s no excuse not to do it.
There are now sufficient numbers of
experienced pilots in Australia alone who have colour defective vision and who
form a ready pool of willing test subjects to resolve the nagging doubts some
may genuinely have as to the wisdom of abandoning the standard. Measure their
performance in real life aviation tasks, and use the same criteria as are applied
to assess the performance of colour normal pilots. Avoid the trap so often
employed by the serious and dedicated protectors of converting the task into a
de-facto colour vision test. That approach always begs the question and is
simply poor science.
If I could afford it, EFIS would be a
welcome addition to my own aircraft’s panel. I make no suggestion that colour
not be used. I, a dichromat, a deuteranope, love it. Though „wavelength
crippled“, my sense of colour enriches my life immeasurably.
I welcome constructive feedback and even
criticism of the ideas put in this publication, and wherever possible, I shall
endeavour to reply honestly and openly to both.