Sea Eagle, I have to take issue with some of your comments.
Firstly Two documents are required to legally pilot an aircraft, a suitably endorsed licence and a separate medical certificate. Mr. Hepel had the former but not the latter.
As for CASA being able to prevent Mr. Hempel from using an aircraft, please give them some credit. Exactly how are they able to do this in the face of a decision by someone to deliberately break the law?
Road users are occasionally caught without licences. Mr. Hempels situation is not much different from a car driver. Since aircraft are very expensive and flown by multiple pilots, "wheel clamping" is not a practical option.
It "may" be possible to detect an offence by detecting an aircraft associated with a particular person, but you can't pull over an aircraft.
With regard to medical standards, yes they do exist for train drivers and other rail personnel. I 've linked to the standard and its administration below.
In my limited opinion, I wish pilots were treated as well as train drivers. The standard is quite specific and a model of administrative clarity compared to the arcane and some would say capricious and unfair aviation medical system pilots have to endure. I particularly like the rail categories of "fit for duty, subject to review" and "temporarily unfit" that seem to be more useful than the "on/off" system used in aviation.
Perhaps if Mr. Hempel had the benefit of the train drivers system this accident wouldn't have happened.
http://www.ntc.gov.au/filemedia/Repo...ol2May2004.pdf