Federal investigators have yet to discover evidence that the two radars on the Cosco Busan malfunctioned before the ship hit the Bay Bridge, as crew members have said.
The bar pilot — the man tasked with steering the cargo ship out of San Francisco’s waters — has alleged that distortions on the radars led operators to switch over to an electronic charting system to help guide the vessel in heavy fog.
Questions have been raised about the “symbology” on the electronic system and whether operators in fact steered toward the bridge’s base when they thought they were headed for safe passage between the two towers.
Investigators with the National Transportation Safety Board, which will offer a report and safety recommendations when the investigation is completed, interviewed the pilot who brought the Cosco Busan into San Francisco as well as the pilot who took over the vessel after the collision.
Capt. John Cota, who piloted the ship during the accident, said both the short-range and long-range radars on board the Cosco Busan became unreliable at the same time, NTSB spokesman Peter Knudson said.
A technician has also reviewed the two radars and the electronic charting system, investigators said.
“We have not received any reports of specific equipment problems on the vessel,” said Debbie Hersman, an NTSB board member.
John Meadows, Cota’s attorney, has said his client told authorities that when he boarded the ship that morning, he found the radar did not work properly. The ship’s captain and Cota fixed it before leaving the berth, but south of the Bay Bridge the radar image became “distorted,” Meadows said.
Switching to the electronic charting system, the captain identified what was thought to be the span between towers on the charting system, he added.
The NTSB is also examining whether the Coast Guard’s Vessel Traffic Service fell short by failing to warn the ship’s pilot that he was in danger. The VTS, which plays an advisory role to ships in the Bay, monitored the ship’s course as it approached the bridge but chose to go silent for about two minutes before the collision.
VTS personnel didn’t attempt to warn the pilot he was in danger, Hersman said.
The ship drew the attention of the VTS when the vessel began traveling parallel to the bridge. The VTS staff radioed to the ship to ask its intentions, Hersman said.
When Cota replied, the watch standers intentionally went silent, during “what they perceived as a critical maneuver,” Hersman said.
It was about two minutes between the VTS inquiry and the pilot’s radioed report that he had struck the bridge tower fender, Hersman wouldn’t comment when asked whether the VTS should have advised the pilot the ship was in danger.
“We are looking at what [VTS’] guidance is, what their qualifications are and what the standards for communication are — whether or not there are any obligations beyond advisory info,” she said.
The Associated Press contributed to this report.