The Empire Strikes Back! on Colour Defective Pilots

[Arthur Pape]

I am heartened by the many wonderful and thoughtful contributions to this thread since its inception. I thought I would explain, in as few words as possible, what I see as the fundamental issues at the core of this topic.
The Aviation Colour Perception Standard (ACPS), as specified by ICAO and replicated by practically all signatory states, requires that: “The applicant shall be required to demonstrate the ability to perceive readily those colours the perception of which is necessary for the safe performance of duties.”

At its philosophical/scientific core, this so-called “standard” represents a conclusion (or argument) based on three implicit assumptions, as follows:

• There is extensive use of colour-coded information in the aviation environment.
• The “safe performance of duties” in the aviation environment is dependent on “the ability to perceive readily those colours necessary etc etc……..”.
• Without ‘the ability to perceive readily those colours, the perception of which is necessary for the safe performance of duties”, these duties will be performed unsafely.
  
  The validity or “truth” of the ACPS relies entirely on the validity or “truth” of each of the three assumptions. In turn, the validity or “truth” of each of the assumptions relies on evidence, as opposed to opinion and/or established prejudice.
  
  Let’s consider the first assumption. At the dawn of aviation, over a hundred years ago, colour coding was used solely in the form of signalling by means of coloured flags or lights, as the means of communication between people on the ground and in the air. It was suggested that people who could not readily perceive the colours of those signals might perform their duties “unsafely”, and that suggestion, under the circumstances of the day, would have had some merit. Out of this there arose the ACPS, whose wording has changed little from those heady days of cloth covered aeroplanes and simple instructions to pilots using simple coloured objects in a simple “code”.
  Since then there has been an exponential increase in the use of colour throughout the aviation environment, both in the aviation physical environment and in and on aeroplanes. The list of uses of colour is enormous, and the validity of the first assumption is self-evident to anyone with even a minimal knowledge of the aviation environment.
  Result: Assumption 1 is “True”.
  
  Assumption 2 is, however, problematic. For this assumption to be valid, it needs to be demonstrated that the perception of the colour(s) is sufficient and necessary to see the information that is required for the “safe performance of duties”. In other words, “see the colour” equals “see the information”, which results in “safe performance of duties”. This assumption could be tested empirically, but this type of work has never been done in respect to the aviation environment.
  Result: Assumption 2 remains an unproven assumption
  
  Assumption 3 is also problematic. To paraphrase assumption 3, would go like this: “see no (or different) colour” equals “see no (or wrong) information” which results in “unsafe performance”. To digress briefly, let me state that the existence of individuals with colour vision deficiencies (CVD) is a proven reality. That 8 to 9 percent of the male population and just less than 1 percent of the female population have one or other of the various types of CVD is beyond any doubt. Further, there are numerous reliable and proven tests available to detect and classify the severity of any particular CVD condition. Let me add also that the CAD test is an excellent test to diagnose and quantify CVD conditions.
  So, in short, the ACPS, via the implicit Assumption 3 would predict that people with CVD should perform the duties (involved in flying an aeroplane) unsafely. This proposition could be tested empirically (i.e., by measurement, observation and analysis). No formal empirical testing of assumption 3 has ever been conducted.
  
  It is a fact that pilots with CVD have been around for a very long time and in considerable numbers. For almost a century, the FAA has applied a wide variety of colour vision tests and practical tests, whereby tens of thousands of CVD pilots either passed the ACPS or were granted waivers against the standard. Since 1989, a few thousand Australian CVD pilots have enjoyed the freedom to fly at night and many hundreds have achieved successful careers in airline operations. If Assumption 3 were “true” one would expect there to be evidence of “unsafe performance of duties” by these pilots. This should be particularly evident in the incident and accident records kept by the aviation authorities of the USA and Australia. A landmark study in the mid 1970s by two researchers (Dille and Booze) working for the FAA examined the accident records of the large group of CVD pilots with a “waiver” and found not even one accident where the existence of a colour vision defect could have contributed to the cause. Furthermore, the accident rate for this group was no different than that of the general pilot population (accidents per 100,000 hrs of recent experience). Until 2002, the FAA had no record of any accident attributed to CVD, and since 2002 there have been none. The significance of 2002 is that in that year a Fedex B727 crashed while on a PAPI-guided night visual approach, and the CVD status of the flying FO was attributed a causal role in the crash. However, two other crew had normal colour vision and did not see what the PAPI should have been showing them. The relationship between this crash and the significance of CVD is highly contentious. The ATSB and CASA have admitted they have no record of any accident attributed to CVD.
  
  The Australian experience since the Denison case in 1989 has provided excellent positive evidence against the “truth” of Assumption 3. There are estimated to have been several thousand CVD pilots operating with either no restriction or minimal restriction in the period in question, and a significant number at the highest level of airline operations. I can say with confidence that we have examples of even the most severe kinds of CVD working as captains and FOs on the full range of airline type aircraft. These pilots are surveilled, trained, tested and examined in exactly the same way that pilots with normal colour vision are handled. They pass and keep on meeting all requirements “necessary” for the “safe performance of their duties”, and these assessments are made by duly qualified examiners of airmen, as opposed to aviation medical doctors or optometrists. This is taken by many informed commentators as evidence that Assumption 3 is “false”, and raises the question as to whether the ACPS serves any useful role in modern aviation.
  
  It is abundantly evident that the appeal by John O’Brien and the unprecedented interrogation of CASA on this topic in the Australian Senate has triggered a tsunami of hysterical and irrational activity within CASA. It is my view that CASA’s actions and the responses by the Director and the Principal Medical Officer to the Senate Estimates Hearings reflect an absurd and indefensible position. Claims of “medical evidence” by both in support of their stance cannot be substantiated because such evidence does not exist.
  
  There is no “rocket science” in any aspect of this saga.