Scatter Cat and Sunnywa. Your posts are honest and loyal to the SAR community which I respect a lot.
a lot of confusing and sometimes conflicting information on this thread. However we know that descending below MSA over the sea, can only ever be safely done with an ACCURATE RADAR IMAGE. FLIR and NVG add value but the RADAR and the RADALT are priority.
I have operated under 2 assumptions for 30 years, 1. that the radar locks out at 0.5 Nm and 2. You need to start the RADAR with as full and cluttered an image as you can tune in, and then back it off for clarity. This may not have been the correct scientific approach.
This crew were monitoring the radar. The CVR has calls accordingly. Something went tragically wrong with the WX radar setup, serviceability or software.
While in the SAR community there will be options now to recommend NVGs IFR letdowns etc, taking into account all possible safety systems, for the O&G community, they continue to do this kind of letdown in solid IMC (ARA) with ONLY the RADAR to rely on.
In older aircraft I have flown where the RADAR has its own "Telly" not much went wrong. It either worked or it didn't. However in modern multidisplay overlay technologies I have experienced a few kinds of software glitches which I am ashamed to say, fixed by some reconfiguration and rarely reported.
If this terrible event was caused by a faulty radar image or overlay problem we as a community need to start accurately documenting the insidious issues with overlay technology.