Ehime Maru and USS Greeneville Collision - Incident - Prelude

Prelude

On January 10, 2001, the Ehime Maru, a Japanese fishing trawler owned by the government of Ehime Prefecture, 191 feet (58 m) in length and weighing about 500 tons (500,000 kg), departed from Uwajima Fishery High School, a secondary school in Uwajima, Ehime Prefecture, Japan. The ship, captained by Hisao Ōnishi, headed for Hawaii on a planned 74-day voyage to train high school students who were interested in pursuing careers as fishermen. A total of 35 people were on board Ehime Maru: 20 crewmembers, 13 students, and two teachers. The ship's curriculum included long-line tuna fishing, maritime navigation, marine engineering, and oceanography. The ship docked at Honolulu Harbor on 8 February.

On 9 February, the USS Greeneville, a U.S. Navy nuclear-powered attack submarine, prepared to depart Pearl Harbor, Hawaii, to conduct a public relations mission under the USN's Distinguished Visitor Embarkation (DVE) program. The program took civilians, members of Congress, journalists, and other "opinion makers" for rides on nuclear submarines to demonstrate the submarines' capabilities; its goal was to demonstrate the need to maintain a fleet of nuclear-powered submarines. Greeneville had previously participated in several DVE missions, carrying notable civilians like Tipper Gore and James Cameron. For this mission, Greeneville was to carry 16 civilian DVs, including 14 CEOs and a sportswriter and his wife. The CEOs were in Hawaii to support a fundraising effort to restore the retired battleship Missouri. This DVE visit had originally been arranged by retired Admiral Richard C. Macke. Accompanying the DV civilians on the mission was Navy Captain Robert L. Brandhuber, Chief of Staff for Rear Admiral Albert H. Konetzni Jr., the commander of the submarine component of the United States Pacific Fleet, abbreviated as COMSUBPAC.

Before departing on the mission, the captain of the Greeneville, Commander Scott Waddle, was informed that the ship's Analog Video Signal Display Unit (AVSDU) was inoperative. The AVSDU was an analog video monitor, located forward of the submarine's periscope in the control room, that displayed information from the sub's three sonar stacks and screens. The monitor helped communicate sonar information to the officer of the deck. Waddle decided to continue with the mission without attempting to repair the monitor, believing that it was not a crucial piece of equipment.

Greeneville departed Pearl Harbor on time at 08:00 local time (HST) with a crew of 106 in addition to the 16 DV passengers and Chief of Staff Brandhuber. As the submarine transited the ship channel from Pearl Harbor, Waddle noticed that the weather was "hazier than normal", but he thought that the haze would burn off shortly. Greeneville reached its dive point south of Oahu (21°6′N 157°55′W / 21.1°N 157.917°W / 21.1; -157.917) slightly later than scheduled, at 10:17, and submerged. The DVs were scheduled to be served lunch in two sittings, the first from 10:30 to 11:30 and the second from 11:30 to 12:30. After lunch, the submarine was to display its operational abilities and then return the DVs to Pearl Harbor for a reception that was scheduled to begin at 14:30. The lunch service ran late, and other Greeneville officers repeatedly reminded Waddle that the submarine needed to begin its demonstration maneuvers or it would be late back to port. Finally, at 13:10, Waddle entered the submarine's control room and prepared to execute the demonstration. Fifteen of the 16 DVs and Brandhuber entered the control room to observe the maneuvers.

Meanwhile, at 12:00, Ehime Maru had departed Honolulu harbor en route to fishing grounds about 300 nautical miles (560 km) south (14°N 156°W / 14°N 156°W / 14; -156) of Oahu. By 12:50, the ship was proceeding at 11 knots (13 mph; 20 km/h) about 8 nautical miles (15 km) south of Oahu and was nearing the area where Greeneville was conducting the DV cruise.

Three crewmen were on duty in Greeneville's sonar room. At 12:30, the submarine's sonar operators detected a surface vessel in the vicinity and designated the contact as "Sierra 12" (S-12). A few minutes later, they detected a second vessel about 20 nautical miles (37 km) away, which was designated as "Sierra 13" (S-13). S-13 was Ehime Maru. Also tracking the sonar contacts in the control room was Patrick Seacrest, Greeneville's sole fire control technician on duty at the time. Seacrest was responsible for "determining the course, speed, and range of surface and submerged vessels (or targets) potentially posing a threat to the submarine." At 12:58, Seacrest designated the track of S-13 as heading away from Greeneville's location. Beginning at 13:00, Seacrest elected to discontinue updating the Contact Evaluation Plot (CEP) in the control room. The CEP is a "labor intensive" paper display that plots ship data and contact information for reference by control room personnel. Seacrest stated that one of the reasons that he decided to stop updating the CEP was that the DV guests were standing between his watchstation and the CEP.