Belgique..
Sorry to be the bearer of unpallatable news (pun intended
) but pallets shift..often! Usually they are, as 411 says, empty and are of minor inconvenience. They only cause embarassment to the loaders and a banging noise in the cabin.
If a heavy pallet shifts (and they have) expect touble.
I am not saying that this incident was caused by shifting cargo, but it is a possibility.
I have no axe to gring here just offering (I hope) constructive comment.