National Transportation Safety Board
Office of Public Affairs
The National Transportation Safety Board is continuing its investigation of the February 9, 2001 collision between the nuclear submarine, U.S.S. Greeneville, and the Japanese fishing vessel Ehime Maru. Nine of the 35 persons aboard the Japanese vessel, which sank after the collision, are missing.
The following is updated factual information documented by NTSB investigators in Washington, D.C. since the departure of the Board's investigative team from Hawaii on February 24.
The USS Greeneville was equipped with a sonar data logger that recorded sonar data and "own ship" data once per second. Data for the accident were transferred to a data tape (normally used for archiving data). This data tape is en route to NTSB headquarters for analysis. However, the Navy has provided the NTSB with a preliminary data file containing parameters extracted from this tape. Heading and keel depth from this data file are plotted for a 10 minute period that includes the collision in figure 1. The NTSB has not applied any instrument corrections to these data.
Figure 1: Preliminary Greeneville Depth and Heading
Although the submarine's position was not recorded, it is possible to derive the Greeneville's track from recorded heading, speed and pitch data. Figure 2 shows this derived track with the radar track of the Ehime Maru.
Figure 2: Preliminary Greeneville and Ehime Maru Track
Figure 3 shows the radar track of the Ehime Maru and the last 15 minutes of the derived Greenville track before the collision and the Greeneville's return to the accident site on the surface in 3 dimensions. The surface dimension is 2 ½ by 2 ½ nautical miles.
Figure 3: 3D view
NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.