Seabreeze,
In any regulatory change, CASA has the responsibility for a process that fundamentally starts with the justification of the rule, roughly the "safety case".
As we know, despite the "rules for rules" being Government policy, and despite any number of apparently authoritative guides to the process, the latest being the "Brown Book", the Australian Government Guide Regulation,
<https://www.cuttingredtape.gov.au/handbook/australian-government-guide-regulation>
this and similar are all too often ignored by CASA and quite a few other government organisations.
If an airline wants a concession, they have to make the case for the concession.
Despite Government policy that seems to suggest the opposite, the internal CASA "policy" is "we can do anything we like". Just ask Polar Air. They will tell you it cost them $1.5M to find out CASA can do whatever they like.
Tootle pip!!