The Navy captain who slammed the USNS Mercy into the USS Arizona Memorial in May apparently did so after he “lost track” of his own ship.

After seven months of investigation, the Navy concluded that Capt. Thomas Giudice was unable to control the tug boats pulling the USNS Mercy. The captain and the ship’s pilot lost complete track of where the ship was for three minutes, a crucial misstep that caused the ship to ram straight into the USS Arizona Memorial’s dock.

The momentum of the ship’s propellers sent the dock 12 feet backwards. The entire museum was closed for a week after the USNS Mercy incident as the military repaired the dock.

In the final Navy report, the branch chalked up the incident to human error. An off-duty witness quoted in the report said that the ship very nearly crashed into the memorial itself.

“… somewhere at 30 yards or less from the Memorial, I could see prop wash,” the sailor said. “I could look down and see the turrets of the sunken ARIZONA. I could tell our “ahead bell” had been ordered based on the shaking of the ship and prop wash. If the ahead bell hadn’t been ordered when it was, we would have wiped out the memorial.”

The USS Arizona is the submerged tomb of 1,177 sailors and Marines who perished in the Attack on Pearl Harbor on Dec. 7, 1941. Though most of the wreckage remains at the bottom of the harbor, tourists may visit a memorial and museum right above it to learn about the battle and remember the thousands who died.

Check out the redacted report here.