To respond to Duck Pilot, Mark Skidmore told me that he was leaving CASA because he was sick of "banging his head against a brick wall".
In his case that would have be the Department, acting on behalf of the Minister, because he otherwise controlled the CASA agenda.
Regardless of press releases, the Department is mortified about change, they need the status quo so that the Minister can never be blamed if something goes wrong.
When something does go wrong, as with Angel Flight, then the response must be more regulation, regardless of whether it actually addresses the problem. the Minister is then seen to have acted and all is now well again.
Well done Minister!