Again, the questions merely expose the underlying complexities. An exemption from compliance with a regulation is not the same as the approval of an Ops Manual paragraph. The Renmark tragedy illustrates that CASA sometimes approves Ops Manuals with dangerous procedures in them. That’s why CASA is sometimes a defendant in negligence claims arising from aviation accidents.
I’ll try to explain it like this. Captain Sullenberger and his crew suffered an emergency and ditched into a river (probably above MLW). He did what he judged necessary in the circumstances. No lives were lost.
Nonetheless, Captain Sullenberger was ‘put through the ringer’ by, among other agencies, the NTSB. The NSTB didn’t shrug and say, oh well, Sully had authority to vary the rules as he deemed necessary so we’ll just move on.
The few defences built into the Australian rules – which no PIC has the authority to ‘vary’ when the PIC ‘deems necessary in an emergency’ – are a tiny, withered fig-leaf over the PIC’s exposures that have nothing to do with prosecution action. If I’m involved in accident – touch wood – the least of my worries would be prosecution action.
But I'm again mindful that I'm drifting into legal issues rather than the simple task of location of the requested regulation.