A quick squiz at the pommie rules indicates why they use the CAD test: They are stuck in the Dark Ages (to which CASA is trying to return Australia).
The pommie rules point to Annex IV to the EASA Aircrew Regulation. In relation to colour vision, that Annex says:
MED.B.075 Colour vision
(a) Applicants shall be required to demonstrate the ability to perceive readily the colours that are necessary for the safe performance of duties.
…
Straight out of the 19th Century Big Book of Ship Sailing!
The rule assumes as true that which
used to be true but has been proved to be untrue in modern aviation. The ability to perceive actual colours is no longer necessary for the safe performance of pilot duties.
What the EASA rule would say, if it were based on evidence, is that applicants must demonstrate the ability to perceive readily the meanings of signals, symbols and indications that may be coloured and are necessary for the safe performance of duties.
As I’ve observed before, the current rule is just like the language test that used to be imposed on potential immigrants to Australia to ensure the ‘wrong ones’ were filtered out: “Applicants shall be required to demonstrate the ability to understand readily the languages that are necessary to become a good Aussie citizen.” The prejudice was dressed up as an objective criterion for achieving an unassailably important policy outcome.
This language test is necessary for the preservation of the fabric of our nation! Who would want to risk weakening the fabric of our nation?
Well, as a matter of fact, the test was not necessary for the preservation of the fabric of the nation, but rather the product of narrow-minded, paranoid bigotry.
The ability to perceive colours readily is necessary for the safety of air navigation! Who would want to risk the safety of air navigation?
Well, as a matter of fact, the ability to perceive colours readily isn’t necessary for the safety of air navigation.
MED.B.075 of the EASA Aircrew Regulation goes on to say:
(b) Examination
(1) Applicants shall pass the Ishihara test for the initial issue of a medical certificate.
(2) Applicants who fail to pass in the Ishihara test shall undergo further colour perception testing to establish whether they are colour safe.
…
Because the basic rule is that the applicant must be able to perceive colours readily, it’s no wonder that they’ve opted for the CAD test, because the CAD test is just a glorified colour vision test which, as noted by the AAT, just tells us what we already know: The applicant doesn’t have the ability to perceive the colours that a proper, red-blooded, patriotic pilot can perceive, so the applicant must be a danger to the safety of air navigation. Who could argue with that?
PS: For the person who PM'd me but whose inbox is now full, the UK CAA medical assessment review and appeal process is explained here:
http://www.caa.co.uk/docs/49/2015010...hHearingV6.pdf