On 19 April 1989, the Number Two 16-inch gun turret of the United States Navy battleship USS Iowa (BB-61) exploded.
The explosion in the center gun room killed 47 of the turret’s crewmen and severely damaged the gun turret itself.
On April 19, 1989, the day of the blast, the ship was preparing for live-fire training at Vieques, Puerto Rico Naval Training Range.
At 08:31 on 19 April, the main turret crewmembers were ordered to their stations in Turrets One, Two, and Three. Thirty minutes later the turrets reported that they were manned, swivelled to starboard in firing position, and ready to begin the drill. Vice Admiral Johnson and his staff entered the bridge to watch the firing exercise. Iowa was 260 nautical miles northeast of Puerto Rico, steaming at 15 knots
At 09:53, about 81 seconds after Moosally’s order to load and 20 seconds after the left gun had reported loaded and ready, Turret Two’s centre gun exploded.
A fireball between 2,500 and 3,000 °F and travelling at 2,000 feet per second with a pressure of 4,000 pounds-force per square inch blew out from the centre gun’s open breech.
The fireball spread through all three gun rooms and through much of the lower levels of the turret.
Shortly after the initial explosion, the heat and fire ignited 2,000 pounds (910 kg) of powder bags in the powder-handling area of the turret. Nine minutes later, another explosion, most likely caused by a buildup of carbon monoxide gas, occurred.
All 47 crewmen inside the turret were killed. The turret contained most of the force of the explosion. Twelve crewmen working in or near the turret’s powder magazine and annular spaces, located adjacent to the bottom of the turret, were able to escape without serious injury.
These men were protected by blast doors which separate the magazine spaces from the rest of the turret.
The blame game and the cover-up
Two major investigations were undertaken into the cause of the explosion, one by the U.S. Navy and then one by the Government Accountability Office (GAO) and Sandia National Laboratories. The investigations produced conflicting conclusions.
The first investigation into the explosion, conducted by the U.S. Navy, concluded that one of the gun turret crew members, Clayton Hartwig, who died in the explosion, had deliberately caused it. During the investigation, numerous leaks to the media, later attributed to U.S. Navy officers and investigators, implied that Hartwig and another sailor, Kendall Truitt, had engaged in a homosexual relationship and that Hartwig had caused the explosion after their relationship had soured. In its report, however, the U.S. Navy concluded that the evidence did not show that Hartwig was homosexual but that he was suicidal and had caused the explosion with either an electronic or chemical detonator.
The Senate committee asked the GAO to review the U.S. Navy’s investigation. To assist the GAO, Sandia National Laboratories provided a team of scientists to review the Navy’s technical investigation.
During its review, Sandia determined that a significant overram of the powder bags into the gun had occurred as it was being loaded and that the overram could have caused the explosion. A subsequent test by the Navy of the overram scenario confirmed that an overram could have caused an explosion in the gun breech. Sandia’s technicians also found that the physical evidence did not support the U.S. Navy’s theory that an electronic or chemical detonator had been used to initiate the explosion.
In response to the new findings, the U.S. Navy, with Sandia’s assistance, reopened the investigation. In August 1991, Sandia and the GAO completed their reports, concluding that the explosion was likely caused by an accidental overram of powder bags into the breech of the 16-inch gun.
The U.S. Navy, however, disagreed with Sandia’s opinion and concluded that the cause of the explosion could not be determined. The U.S. Navy expressed regret (but did not offer apology) to Hartwig’s family and closed its investigation.