Looking at the pictures;
It appears that the top floor is catered using an overwing door.
The catering truck has to carefully position itself over the top of the leading edge to access this door.
Is this a normal procedure?
If so, then surely an incident like this was inevitable?
Could very well be. From this side pic, it appears the door is directly over the leading edge fillet. Not sure exactly how they manoeuvre the catering truck into postion for the upper deck.
