Takata's analysis is very thorough and looks conclusive.
However, being a skipper on the A330 myself, I have some doubts for operational reasons:
- deciding to leave the track for a turnback is a serious matter and would be coordinated, if ever possible, with ATC.
- If unable due to urgency or no contact, broadcasting the intention on 121.5 is certainly a high priority.
- Assuming, the reason was for a crippled aircraft: VHF #1 is connected to the DC-essential bus and available in ELECTRICAL EMERGENCY CONFIG. Assuming there was no complete electrical loss at the time of a turnback-decision (which would render a turnback almost impossible because of flight in MECHANICAL BACKUP), another aircraft should have catched such a transmission.
I would also like to hint to funfly's conclusion with no signs of an ongoing preparation for an emergency in the cabin (e.g. deployed lifevests)
Thomas