May 20 (UPI) -- The National Transportation Safety Board, which is investigating Saturday's deadly crash of a Mexican Navy tall ship into New York's Brooklyn Bridge, is focused on the ship's guide tugboats and sudden acceleration. The NTSB told reporters Monday that it was still working with the Mexican government and had not gained access yet to the military ship, called the Cuauhtémoc. "We are optimistic we will have that access very soon," said NTSB board member Michael Graham .