Seeing as a new thread has been started, I thought it would be useful to include a link to the 1989 Australian court case to which outofwhack refers.
Re Hugh Jonathan Denison and Civil Aviation Authority [1989] AATA 84; 10 AAR 242 (7 April 1989)
There’s quite a lot of reading, but I highly recommend anyone with an interest takes the time to read and study it as it will give you a good appreciation of what was examined and the thoroughness of what was involved. Witnesses were called including vision experts and professors in optometry, ophthalmology and psychology as well as experienced airline pilots.
To quote a few pertinent paragraphs from the case:
“31.
Signal lights are rarely used now because of the reliability of communication between air traffic control and pilots. They are used only where radio communication cannot be maintained.
We consider that the possibility that a pilot with defective colour vision may not be able to identify signal lights is not a reason for prohibiting him from flying by night…”
"40. …We are satisfied that, because of the size and brightness of the VASIS lights, changes from one colour to another will be perceived by pilots with defective colour vision as changes both in colour and in intensity. Deutans will almost certainly perceive the red light as such and any other colour as something different. Protans will see the red light as having significantly decreased intensity compared with the other colours.
So there is no significant risk of protan or deutan pilots maintaining the incorrect height during their approach to an aerodrome because of inability to make proper use of the VASIS.”
“44. Dr Samuel gave evidence that a person who had never had very precise colour vision was not going to be particularly reliant on the perception of colour. Consequently, such persons were less dependent on chromatic cues than those with normal colour vision. They might depend more on recognising shapes or changes in luminosity.
He said that it was impossible to tell on the basis of clinical and laboratory tests what a person would do in the real world. He was unaware of any evidence published that protans or deutans had more difficulty passing flight tests than persons with normal colour vision. That appeared to indicate that, when they were tested on practical tasks, they had no difficulty in performing them and that their failure to pass colour-naming tests did not really have any correlation with how they could fly an aeroplane and perform the tasks required for doing so.”
"75. Having given consideration to all of the very considerable amount of evidence presented during these proceedings and with our knowledge of the evidence which was presented in the proceedings in Re Pape,
we have come to the conclusion that a pilot who is a deutan does not, simply because of his defective colour vision, pose a significant and unacceptable risk to the public by flying an aircraft at all or at night or by flying an aircraft equipped with EFIS and EICAS instrumentation.”
"77. As the respondent has requested us to do so, we have stated our views inrelation to pilots who are protans. In summary, we are satisfied that,
so far as the instrumentation of aircraft is concerned, a pilot who is a protan will not be at a significant disadvantage compared with a pilot with normal colour vision.”
"78. We
recommend that suitable practical tests should be devised so that a protan can be tested individually…”
“79. Finally, while recognising that the Tribunal has no power to review decisions of the Authority to set medical standards under regulation 62, we suggest that protanomals ought not to be totally prevented, as they are at present, from meeting the colour vision standard.”
It's interesting to note that even in paragraph 31 above, that the tribunal agreed way back in 1989 that control tower signal gun lights were all but irrelevant in the modern age. Yet it's ironic, that even today in 2012, CASA are still using this as a"practical" test.
It also specifically mentions in paragraph 44 that laboratory tests (eg. CAD, farnsworth lantern test?) were found to be unreliable and beared no correleation to how a pilot would perform in the real world.
Even twenty three years later, ICAO’s own Manual of Civil Aviation Medicine states in section 11.8.29
“The problem with colour vision standards for pilots and air traffic controllers is that there is very little information which shows the real, practical implications of colour vision defects on aviation safety.”
The only “practical” way to assess a person’s CVD and its effect on aviation safety is to do so in an aircraft or simulator. This is already being done in Australia, with hundreds (if not thousands!) of CVD pilots now working at the highest levels of the industry including as airline captains. We pass our regular check rides to exactly the same standard as colour normals!
This would never have occurred if it wasn’t for Arthur Pape’s persistence and dedication to the cause. Through CVDPA, we can begin to coordinate legal challenges around the world so that others can enjoy the same freedoms as us in Australia. It can only be achieved though through us all uniting and showing our support.