1. Did they really choose to fly over red blobs at 200 feet with the RADALT complaining?
As has been pointed out already, they were in GMAP mode and so the islands would have been Magenta 'blobs', and this raises the very real possibility that the return for Blackrock could potentially have been partially masked by the magenta waypoint symbol and name label. I'm sure SAR crews will have been experimenting with this already by now to see if they can replicate it.