Originally Posted by
matkat
Stu/Blake if the seat was from the cockpit it may well be the engineer previously mentioned and manifested.
I believe the engineer's body has been recovered (based on the obituary postings on FB from those who knew him). And engineers who accompany flights which is common in Indonesia normally sit in the cabin (something to do with cockpit authority gradient) and usually at the back or emergency exit row if not taken by a passenger who has paid more for the extra legroom.