NTSB Releases "Black Box" Timeline of Baltimore Bridge Strike

Published Mar 27, 2024 10:20 PM by The Maritime Executive

On Wednesday, the National Transportation Safety Board released an initial timeline of events in the tragic collapse of the Francis Scott Key Bridge, which was struck by a container ship and destroyed early Tuesday. The agency has received an initial tranche of voyage data recorder (VDR) information from the U.S. Coast Guard and can now sketch out a rough outline of what transpired aboard the vessel. 

At about 0039 hours on Tuesday morning, the boxship Dali got under way from Baltimore's Seagirt Terminal with 21 Indian crewmembers, two local pilots and 56 hazmat containers on board. The pilots released the docking tugs shortly after, and the vessel entered the ship channel. 

At 0124 hours, Dali was under way in the channel, making eight knots and steering 141 degrees. At about 0125, multiple alarms went off, and the VDR ceased recording the ship's electronic system data. Using backup power, the VDR kept recording bridge audio, and it captured the pilot's verbal rudder commands. 

One minute later, at 0126, the VDR was able to resume recording the ship's electronic data. Shortly after - at 0126:39 - the pilot made a general VHF call for tug assistance. This was the first distress call from the vessel. 

At about this time, a dispatcher at the pilot's association contacted the duty officer at the MDTA, the state authority that operates the Francis Scott Key Bridge.  This gave the MDTA enough early warning to begin shutting down the bridge to traffic, an action that officials have credited with saving many lives. 

At 0127:04, two minutes before contact with the bridge pier, the pilot gave the order to drop Dali's port anchor. He also gave additional steering commands.

At 0127:25, the pilot made a general radio call over VHF to warn that the Dali had lost all power and was approaching the Key Bridge. By this time, MDTA's duty officer had dispatched units to shut down all lanes of traffic.  

The ship was still making seven knots at 0129:00, the moment that the VDR began recording the audible sounds of the allision. The noise continued until 01:29:33, and the pilot made a VHF call to report the bridge's collapse a few moments later. 

NTSB began interviewing crewmembers today, agency chair Jennifer Homendy said at a press conference. The first interviews with the pilots are scheduled for tomorrow. For the immediate term, the agency's focus is on collecting any evidence that could be erased by activity at the site, preserving data before salvage operations begin in earnest.   

Homendy noted that some of the containers on the bow have been breached, including some hazmat containers, and that a sheen has been spotted on the water. The area is dangerous to access, and federal and local responders are aware of the damage. 

Though the composition of the sheen and release is not known, the ship's hazmat cargo was mostly corrosives and flammables, along with miscellaneous hazmat - a typical classification for lithium-ion batteries.