I've had to restart this area three times now due to a bug that prevents completion - on the PC, if you burn the trees in the order that you're supposed to, the plane breaks incorrectly and you cannot complete the DLC.
I've found a few links (1, 2) that claim to have workarounds, but they're very unclear (eg. "Start with the right-most fire" does not help, as there are two rightmost fires!)
Also, apparently Eidos believes they fixed this issue, but they definitely have not, as I just today encountered it (PC, Steam version, latest update).
So, what order do I have to light the fires to work around this bug?
21 Answer
Was able to complete tomb after just stepping outside of it and coming back in, You will hear a distinctive tone indicating you've left the tomb, at that moment you can turn around and the glitchy part in the plane seems to have resolved itself in your absence.
