Colour Vision Requirements for Aircrew

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Ryan E Brookes, September 2015

DTA Report 405

New Zealand Defence Force - Defence Technology Agency

Colour Vision Deficiency (CVD) is a condition that results in individuals being unable to distinguish differences between certain colours. The condition is most commonly inherited, affecting approximately 8% of men and a smaller proportion (0.5%) of women. Exclusion of applicants with CVD reduced the number of potential candidates available for selection as aircrew.

A continuum exists in the severity of CVD. At the most benign end of the continuum an individual may have near normal colour vision. At the opposite extreme, an individual may be monochromatic. The latter is extremely rare.

The compatibility of CD with crewing aircraft is assessed by medical personnel using clinical diagnosis tests. These clinical tests were developed specifically to detect the presence, nature and severity of CVD. No clinical tests yet provide a measure of vocational performance in operating an aircraft.

Despite the lack of relevance to vocational performance, arbitrary pass marks have been assigned to clinical tests such that a failing candidate will either be subject to operational restrictions or excluded completely. The prescribed clinical tests and associated pass marks vary considerably between regulators. While an individual may be subject to no restrictions in one jurisdiction, they may be excluded in another.

In many civil and military populations, waivers have been given to CVD subjects demonstrated competency in an operational environment. In some cases, waivers were issued simply to achieve intake quotas. There is no record of such candidates suffering difficulty on operations as a result of their CVD. To the contrary, there is much evidence to indicate that candidates with CVD, when aware of their condition, have been able to perform operational tasks to the required levels of competence.

This report presents and discusses available literature which indicates that aircrew with CVD are able to operate safely and effectively. The evidence raises questions about the suitability of current clinical test regimes as a means of restricting or disqualifying applicants. Consistent with the findings of NATO and the practice of some regulators, it is instead recommended that a practical or operational check, to identify practical handicaps as a result of CVD, is a more relevant and fair method by which to determine when an applicant can safely crew an aircraft.

The Puzzle of the Crash of Fedex Flight 1478:  Implications for Colour Vision Standards in Aviation

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Dr Arthur Pape, co-written by Prof Boris Crasini, October 2013

Published in the Journal of Australasian Society of Aerospace Medicine

During the final approach to land on Runway 9 at Tallahassee Regional Airport, Federal Express (FedEx) Flight 1478 crashed into a forest about a mile short of the Runway 9 threshold. The Precision Approach Path Indicator (PAPI) device servicing the runway was supposedly showing four red lights during this final approach, providing colour-coded information that the approach was too low for a safe landing. The First Officer, piloting Flight 1478, had a colour vision defect, and the crash has raised the question of whether colour vision standards in aviation should be more stringent than they currently are.

In this paper, we argue that the crash of FedEx Flight 1478 raises the more fundamental question of whether colour-coded information should be used at all in aviation. The basis of our argument is this puzzle: While the First Officer, piloting, had defective colour vision, the Captain and the Flight Engineer, both actively involved in the approach to land of Flight 1478, had normal colour vision, yet did not seem to see, and certainly did not make use of, the colour-coded information supposedly provided by the PAPI device. We describe how the National Transportation Safety Board’s (NTSB) Report implicitly acknowledges and attempts to explain this puzzle. We propose an alternative explanation of this puzzle, and conclude by considering the implications of this alternative explanation for colour vision standards in aviation.

Colour Perception Standards in Aviation: Some Implications of the AAT Decisions Regarding Colour Perception and Aviation

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Dr Arthur Pape, co-written by Prof Boris Crassini, December 2011

Published in the Journal of Australasian Society of Aerospace Medicine

The International Civil Aviation Organisation (ICAO) colour perception standard may be analysed as a form of argument; that is, it may be considered as a conclusion drawn logically from three assumptions. These assumptions are (i) that colour is used extensively as a feature of informationpresentation systems in aviation; (ii) that normal colour vision is necessary for safe information processing from such systems, and consequently, safe performance of the duties of aviation, and (iii) that defective colour vision results in unsafe information processing from such displays, and consequently, unsafe performance of duties in aviation. For the application of the ICAO colour perception standard to be evidenced-based, the truth or falsity of each of these assumptions needs to be evaluated using appropriate empirical tests.

An informal demonstration of an empirical test of the second assumption is presented showing that the presence of colour is neither sufficient nor necessary for appropriate information processing from one information-presentation system. The limitations of the kind of evidence provided by the demonstration are noted and a proposal for the collection of more appropriate empirical evidence is proposed. This proposal is possible because of two landmark decisions made some 20 years ago by the Administrative Appeals Tribunal (AAT) in Melbourne, Australia, in relation to the aviation colour perception standard. Because of these decisions, pilots with defective colour perception were able to gain extensive flying experience commanding modern, sophisticated aircraft. That is, a group of pilots with defective colour perception now exists having similar flying experience to the flying experience of pilots with normal colour perception. These two groups of pilots provide a pool of possible participants for a more-appropriate empirical test of the assumption underlying the colour perception standard than had been possible before the AAT decisions. A proposal for such an empirical test is outlined.

Aviation Colour Perception: A Time to Reassess

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Dr Arthur Pape, September 1997

Published in ‘Avmedia’ – Journal of Aviation Medicine Society of Australia and New Zealand

Congenital Deutan Defects of Colour Perception in NASA Mission Specialists

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John Sotos MD, December 1998

Published at