It turns out to be an unreasonably large search area, and that is with some assumptions. Most notably I've assumed that the aircraft was able to achieve the specified pitch forwards, which was not clear from the flight data up to disconnect because most of the flight was backwards. But if it switched to failsafe RTH then it will have rotated to face the home point. Anyway, based on the nominal RTH speed of 8 m/s and the range of wind speeds estimated from the flight, that leaves the following 0.4 km² area for the aircraft location at autoland:
View attachment 96486
@sar104 thank you for the work you’ve put in to help find the MM. Much appreciated.
The weather is good today so I’ll be heading out shortly to search again.