...but what's the CAA's proof?...The only hard evidence is the breaking of the Op's manuals 30 min ECT deadline.
How much more do they need? Thems the rules.
As for performance/engine failure, it would seem to me that a non-RNP departure is no different to an RNP departure
Its quite a bit different. An escape path that can have curved legs wherever you want, guided by GPS instead of straight lines to/from a navaid, dead reckoning, arcs and timed turns. Who said the RNP T/O minima is 1000'?
I can't imagine an RPT jet operation zooming up to the base of the cloud, having a look and then figure-of-eighting back down because they were going to go IMC on the Visual Segment
Yep, its true.