Originally Posted by
GE90-115B
If I recall correctly I think crews are allowed to rest in empty J seats as mentioned above, maybe CX will even block off seats on the last row of the rear cabin for this purpose. The reason why you will never see this happen on a 777-300ER is because it has a dedicated crew rest cabin above the ceiling of the row 60s zone in Y class.
correct - there is no crew rest on the A330.
If allowed by the ISM, crew may be permitted to rest in unoccupied J class seats - but that isn't always the case - especially if the flight is full.
In some cases, the entire 2nd mini cabin will be blocked if loads are low (as happened on a flight the other day I was on).
To avoid crew rest issues, booking a seat in the main cabin may be a good idea.