While it may seem harsh to those that fall foul of the medical requirements, there are genuine reasons for having those requirements and they are actually linked.
For example:
People claim that the hearing requirement for the IR is unnecessary. Chuck Yeager once said "I may be deaf but isn't that what volume knobs are for?" Thus I can sympathise with them when talking about single pilot operations. The medics however claim that the hearing test is not simply a measure of current ability - it allows for reductions before the next test.
As for the colour blindness issue:
IO540 is correct to state that a light at night on a collision course will be steady. That makes it difficult to see. More important then that the pilot seeing that light can differentiate it from the stars or ground lights that may also be seen. Furthermore there is a big difference between what the law requires us to do when we spot a green light converging on us to what we must do when a red light is converging on us.
It must also be remembered that being in IMC has nothing to do with being a) in cloud or b) in reduced visibility. It possible to be in IMC and see an aircraft 10nm away. The rules of see and avoid apply always. However, logic dictates that if you can not or did not see the other aircraft then one could not see or avoid it. There can be reasons other than IMC which make detection of the other aircraft difficult or even impossible - military no lights flights at night - operating at such a speed in the visibility/ airspace that gives insuficient time to etect and avoid other aircraft. The minimum vision requirements including colour perception for those that want to fly at night is only part of the system.
The IR gives pilots the privilege of being able to fly at night without having completed any night take-off or landings within the past 90 days. Thus it is simply logical that the applicant should have demonstrated the ability to fly at night i.e. PPLs need to hold a night qualification and CPLs don't because they had to complete night training to get the CPL.
I wonder how many people are told that they can not be an electrician because they are colour blind? What do they do? Do they try to get the wiring systems changed?
Regards,
DFC