“Let’s try to shoot the gap there.”
Just after noon in the northern Arabian Sea, the captain of a US Navy fuel ship gave the order to take a shortcut through risky waters rather than take a longer, safer route to their destination.
Two hours later, the 677-foot replenishment oiler USNS Big Horn struck the sea floor at high speed, shaking violently as the vessel ran aground. Music was audible on the bridge as sailors missed key navigational warnings.
The Navy command investigation obtained by Business Insider said that the September 2024 incident, initially characterized as an allision, was caused by “a series of poor decisions, failure to follow procedure, application of open water navigation to restricted waters, and failure to exhibit proper risk calculation.”
The ship suffered more than $20 million in damage.
The Navy’s investigation, the details of which have not previously been made public, reveals that the captain and his watchstanders failed to prepare for the shortcut and failed to monitor navigation alerts that could have averted disaster at the last minute.
“The grounding was preventable,” investigators wrote.
The investigation recommended administrative or disciplinary action against Big Horn’s captain and several officers. Military Sealift Command said that both the captain and the ship’s navigator are still employed. It is unclear if they will be permitted to hold their positions again.
“Pursuant to the investigation, all administrative and disciplinary matters were submitted for appropriate review,” command spokesperson Jillian Morris said in response to Business Insider’s query on accountability and discipline. “However, to protect employee privacy, we do not comment on, nor share the details of, the outcome of those matters.”
US Navy photo
Making a risky choice
Shortly after 12 p.m. local time on September 23, the Big Horn was wrapping up its final replenishment-at-sea with ships from the Abraham Lincoln Carrier Strike Group.
The next move for the Henry J. Kaiser-class replenishment oiler, which refuels warships at sea, was to sail from the northern Arabian Sea to the Duqm port in Oman for a scheduled visit.
The new navigator was drafting route options for the captain to get the Big Horn to a pickup point, where the oiler would embark a harbor pilot to guide the ship into port.
During a conversation with another officer, the transcript of which is included in the Navy’s investigation, the navigator expressed concerns about running aground on a particular route and said they preferred an option through deeper water.
The navigator told the officer that they could take the riskier shortcut and save time. “I’m just scared of right here,” they said, “scared of these shallow points.” The officer said they should present the shortcut to the captain.
The officer said “ask the captain and say, ‘This route is about 10 miles shorter but goes through this. Do you feel comfortable?'”
One route, known as Duqm A, was shorter but ran through known shoal areas. Duqm B was a “deep water” path that added several miles to the journey to the rendezvous point.
Just before 12:30 p.m., with the last replenishment-at-sea ongoing, the navigator asked the captain which route they preferred.
“Let’s try to shoot the gap there,” the captain told the navigator, selecting the Duqm A route, even though it threaded a gap between charted shoals dangerously close to the oiler’s draft. The navigator said that they had checked on the under keel clearance, to which the captain replied: “Rad.”
The Navy investigation into the grounding that followed that decision said that there was no indication that the captain reviewed a paper chart during the decision-making process.
‘Slow down, slow down, slow down’
US Navy photo
About an hour later, at roughly 1:30 p.m., the Big Horn completed its final replenishment-at-sea and set out for the pick-up point for the harbor pilot. Pilots are standard for most harbor approaches because they have the local knowledge to help ship captains navigate through tight channels.
Duqm A took the Big Horn through a gap between two charted areas of shoal — or shallow — water known as the San Carlos Banks that were not deep enough for the oiler.
Navy investigators wrote that “attention to detail and consideration of the risks should have negated Duqm A as an option.”
The Big Horn sailed through the San Carlos Banks at 17 to 18 knots. In transit, the ship’s system triggered safety alarms. They were silenced but had visual cues; there is no indication that they were acknowledged.
Meanwhile, the ship’s fathometer — which measures water depth under the hull — showed the water growing progressively shallower.
At 2:12 p.m., the vessel began vibrating as it struck the sea floor.
“Slow down, slow down, slow down,” the captain said.
“We must have hit a shallow spot somewhere, but there is nothing on the chart,” he said moments later as the ship came to a full stop.
Crew members reported fuel leaks on both main engines.
“We must have hit a shallow spot. We must have hit a sand bank,” the captain said.
US Navy photo
The damaged oiler was anchored and later towed into Duqm.
A ‘preventable’ blunder
Investigators found that the members of the bridge team appeared “unreasonably” focused on meeting a 3 p.m. harbor pilot pick-up time, which contributed to the decision to take the risky shortcut at high speeds.
“We gotta haul ass,” the navigator told an officer at one point. In a separate conversation with the captain, they said they believed they could make it, if only slightly behind schedule.
“If we cut corners we’ll get there,” the captain said, per the investigation.
“Yes sir!” the navigator replied. That was minutes before the ship ran aground.
Although the captain later said he did not believe he was operating in restricted waters and was unaware of any safety hazards or navigational concerns, investigators concluded that the Duqm A track met the definition of restricted waters under Navy policy, meaning a formal navigation brief should have been conducted before entering the area.
“However, no members of the bridge team, including the Captain and Navigator, seemed to realize they were steaming into restricted waters,” the investigation said. “No consideration was given for a required navigation brief, a more detailed plan, or thorough review of the proposed track prior to steaming through.”
The command investigation also found that, when the Big Horn ran aground, the ship was operating with two separate electronic navigation chart databases, and there was some confusion among the officers about which one was in use at the time. Safety contours and the shoal area were not clearly displayed.
Records indicate there was music was playing on the bridge up until the grounding. Tug boats brought the Big Horn into port the following day.
The grounding caused extensive damage to the Big Horn’s hull, internal support structures, port propeller, and port rudder. According to Navy cost breakdowns, expenses included roughly $7.5 million for towing, $8.6 million for services in Oman, $1.9 million for fuel offloading, and $2.4 million in additional costs in the US — totaling more than $20 million.
