MM, respectfully I don’t think we’re disagreeing on the core of the issue. We’re just getting there through different avenues.
The aircraft is Cat C so it is legal to fly the circling approach.
Cat D are not authorized to circle even if they are light and use a Cat C speed.
The aircraft is still Cat D and therefore prohibited.
Now….a crew flying said Cat C aircraft are legal to fly a higher speed and it would be prudent to use the higher Cat D minima.
Which in this case would indicate they should not accept the circling approach as cleared by ATC.
Vref is Vref by its definition, it’s not a stall speed. One knot below Vref does not mean instant doom and neither does a standard rate turn at Vref.
Now from the discussion here it appears normal circling speed for the 605 is 150kts which means the crew should have used the Cat D minima and at the lack thereof………