End of Assault On Matmata (veteran)?

I'm playing this on Xbox 360 at the moment and I've got the the courtyard at the end with the AA gun in the middle.

I took cover under the alcove on the right while I picked off the rooftop soldiers. I'm then told to man the AA gun and I reach a checkpoint.

Unfortunately the first aircraft has already begun its bombing run and it kills me instantly about 2 or 3 seconds after the checkpoint. I can't seem to find any safe position in those few seconds that will prevent me dying.

There doesn't seem to be any way of going back to previous save games. Is there anything I can do, or do I have to do the whole mission again (including that very difficult beginning)?