It is not that simple
. The point stating the 11° was very far down on their check-list, and they never arrived at that point (performed only the first page of the 4 pages long procedure). So the 10° was what the Capt decided to hold as the best option from his experience (vast
) as given him the best compromise between sufficient speed for not stalling and sufficiently low speed for not breaking-up when hitting the water.