The US National Transportation Safety Board (NTSB) is investigating the Francis Scott Key Bridge collapse after being hit by the container ship Dali. From the Voyage Data Recorder (VDR), the NTSB has reconstructed the Dali’s voyage leading up to the allision.

The VDR recorded audio from both the ship’s bridge and recordings of the ship’s VHF radios. Additionally, the VDR recorded limited system data, including ship speed, engine RPM, rudder angle, ship heading and some alarm information.

The VDR also recorded the ship’s departure from Seagirt Marine Terminal at approximately 00:39 EDT, recorded the ship’s transit outbound in the Fort McHenry Channel and the striking of the Francis Scott Key Bridge.

Watch a video of NTSB investigators on board the Dali inspecting the ship:

Also read: VIDEO: Bridge collapses after being hit by container ship

An overview of events leading up to the allision

On March 26, 2024, the Dali commenced a voyage from Baltimore, Maryland, bound for Colombo, Sri Lanka, with an ultimate destination of Yantian, China. The vessel had a cargo of 4679 containers. According to the NTSB, the displacement of the container ship at the time of departure was 112,383 metric tonnes. The vessel has a gross tonnage of 95,128.

  • At or about 00:40 local time on March 26, the vessel left berth at the Port of Baltimore with two tugs alongside and a pilot onboard, as is the requisite procedure in the Port of Baltimore.
  • At or about 00:55 local time, the aft tug cast off from the Dali.
  • At or about 00:57 local time, the vessel turned to port.
  • At or about 01:07 local time, the forward tug cast off from the vessel as the ship entered the Fort McHenry Channel.
  • By 01:24 EDT, the ship was underway on a true heading of approximately 141 degrees in the Fort McHenry Channel at an indicated speed over groung of approximately 8 knots.
  • At 01:24:59 EDT, numerous aural alarms were recorded on the ship’s bridge audio. Around the same time, VDR ship system data ceased recording, however, the VDR audio continued to be recorded using the VDR’s redundant power source.
  • Around 01:26:02, the VDR resumed recording ship system data. During this time, there were steering commands and rudder orders on the VDR audio.
  • Around 01:26:39, the ship’s pilot made a general VHF radio call for tugs in the vicinity of the Dali. Maryland Transportation Authority (MDTA) data from around this time indicated the pilot association dispatcher phoned the MDTA duty officer regarding the blackout.
  • Around 01:27:04, the pilot commanded the Dali to drop the port anchor and issued additional steering commands.
  • Around 01:27:25, the pilot issued a radio call over the VHF radio and reported the Dali had lost all power approaching the Key Bridge. Around this time, MDTA data shows the following occurred:
    – MDTA duty officer radios two units already, one on each side of the bridge, to close the bridge.
    – All lanes are shut down by MDTA.
  • Around 01:29:00, the ship’s speed over ground was recorded as just under 7 knots. From this moment, until approximately 01:29:33, VDR radio recorded sounds consistent with the collision with the Key Bridge. Additionally, around this time, an MDTA dash camera shows the bridge lights extinguishing. Additional analysis of the VDR audio and comparison of other time sources will be needed to determine the exact time of contact between the Dali and Key Bridge.
  • At 01:29:39, the pilot reported the Key Bridge down over VHF to the US Coast Guard.

Also read: Baltimore bridge collapse may cause supply chain disruption

Casualties and blocked port

Eight road workers were working on the bridge when it collapsed. Two were rescued from the water, while later, the bodies of two more were recovered. Four remain missing and are presumed dead. Due to debris of the bridge, divers have not yet been able to locate the missing people.

The collapse of the bridge also cut off the Port of Baltimore. At the moment, two temporary shipping channels of limited depth have been opened for essential vessels to be able to reach the port.

Picture (top): NTSB investigators on board the Dali (by NTSB).

Also read: VIDEO: First vessel passes through temporary channel around Key Bridge wreckage [UPDATED]