Two seperate issues here, one is the integrity behind the process and validation of granting control of duty limits to business operators. The reason put forward is that fatigue management rules need to take into account the scientific findings concerning the subject matter. I believe that the previous CAO 48 did just that, it was devised by mature aged aviators who had experienced the wider spectrum of life experiences and used that as the basis to determine what are reasonable and safe limits for periods of work.
In my view this research based approach carries just as much validity as scientific research limited to one (biological) aspect of the human condition. I am unsure about the scientific evidence used to support that fatigue will be reduced by granting control to the business operator. Imperical data may suggest otherwise. Within this new framework part of the operator's obligation to set controls for management of fatigue is to take into account the environment under which the work will be performed, however there does not appear to be any scientific formula as to how these factors will applied instead it will be left to the discretion of the operator.
The other issue is, if a bargain is struck for X amount of remuneration for Z amount of working hours, if an industrial agreement is tied to a regulatory document that is substantively altered to its previous form does this mean one will carry out duty for thirty seven and half hours per week or seventy two hours per week?