No OM, it's over the sea, just an IAP - both the skipper & the jumpseater picked up the DME discrepancy inside the IAP.
Easy to sit in front of your PC & theorize - try doing it on a dark night at 180 knots when all other indications are what you're used to seeing & there's no flags.
These guys did a great job & we can all learn a lesson here.
4HP