Alarms Sound, Then A Scramble To Save Lives: See The Timeline Of The Key Bridge Collapse

BALTIMORE, MD — Over the course of four minutes, alarms sounded as a ship lost power and scrambled to avoid striking the Francis Scott Key Bridge in Baltimore. The 984-foot cargo ship called for help, but it was too late. The ensuing bridge collapse killed six construction workers — two bodies have been found and four are presumed dead.

Here is the timeline of what happened in the early hours of Tuesday, March 26, according to officials with the National Transportation Safety Board:

12:39 a.m. — The ship, named Dali, departs the Seagirt Marine Terminal.

1:07 — Dali enters Fort McHenry Channel.

1:24 — The ship moves trough the channel at 8 knots, or 9 mph.

1:24:59 —Numerous alarms sound, as recorded on the ship's bridge audio. Dali's voyage data stops recording, but the audio communications continue recording because of a second power supply.

1:26:02 — The ship's data resumes recording. Steering commands and rudder orders can be heard on the audio during the lapse in data recording.

1:26:39 — The ship's pilot requests the assistance of tugboats nearby over the VHF, or Very High Frequency, radio. The Association of Maryland Pilots dispatcher phones the Maryland Transportation Authority around this time to alert the MDTA duty officer of the blackout.

1:27:04 — The pilot orders the crew to drop its port (left) anchor and gave additional steering commands.

1:27:25 — The pilot reports via VHF that Dali has lost all power approaching the Key Bridge in the Patapsco River. MDTA data from around this time shows that the duty officer notifies two police units via radio, one already stationed on each side of the bridge. The MDTA Police duty officer orders those units to close Interstate 695 approaching the crossing. Officers successfully shut down all lanes onto the bridge.

1:29:00 — The ship's speed is recorded at just under 7 knots or 8 mph.

1:29:33 a.m. — For about 33 seconds, the ship's audio records sounds consistent with the Key Bridge collapsing. Investigators said they need more data to determine the exact second Dali struck the Key Bridge.

1:29:39 — The pilot reports that the Key Bridge had collapsed in a VHF radio call to the U.S. Coast Guard.

Read all of Patch's Key Bridge collapse coverage here.

Next Steps For Investigation

The NTSB hopes to publish a preliminary report in two to four weeks. A final report on the causes and recommendations is expected within 12 to 24 months.

"It's a massive undertaking for an investigation," NTSB chair Jennifer Homendy said at a Wednesday press conference. "But this is not new for the NTSB. We've conducted other investigations of bridge strikes, bridge collapses."

All of the ship's data and VHF radio calls came from its Voyage Data Recorder or VDR. The VDR is required to record 30 days of history. The NTSB has received six hours of VDR data, from 12 a.m. to 6 a.m. Tuesday, and still needs to analyze the rest.

The Coast Guard recovered the VDR and gave it to the NTSB, which is leading the investigation.

The NTSB is an independent federal agency. It investigates every civil aviation accident and significant events in all modes of transportation, including bridge collapses and marine accidents.

The NTSB is convening a group of experts to analyze the VDR and transcribe the audio transmissions from the calls. The audio quality varies because of the significant background noise. Investigators must filter the audio to hear verbal communication more clearly.

"Our mission is to determine why something happened, how it happened and to prevent it from reoccurring again to save lives," Homendy said.

NTSB investigators said they boarded the vessel Tuesday night. They said Tuesday was focused on ushering in resources from around the country, setting up their family assistance program and getting their bearings.

Investigators said they won't give any safety recommendations or conclusions while on-site. Their focus on the scene is collecting any perishable evidence.

"That's documenting the scene. It's taking photographs. It's taking any sort of electronics or components," Homendy said. "Whatever goes away once the scene is cleaned up, we need to collect that information for our investigation."

Dali had 21 crew members and 2 pilots onboard at the time of the accident. Pilots are local, state-licensed navigators required to take control of ships as they enter and exit the Port of Baltimore. The pilot is only in charge in the Baltimore area. The captain returns to control afterward.

The NTSB started interviewing crewmembers on Wednesday. It will interview the pilots and first responder witnesses in the Key Bridge area on Thursday.

Investigators will gather facts from the Coast Guard, the MDTA and the Association of Maryland Pilots during its fact-finding phase.

The NTSB has requested the cooperation of Dali owner Grace Ocean Private Limited and operator Synergy Marine Private Limited.

Investigators have requested the ship's maintenance and inspection records. Engineers will examine Dali's design, vessel propulsion, steering and power operations.

It also requested bridge inspection records from the MDTA, which operates the Key Bridge. Homendy said the bridge was in "satisfactory condition."

The NTSB also plans to sample the fuel to see if it was contaminated. It will also determine if the ship ever lost power before the day of the crash.

"The world relies on us to be independent, thorough, fact-based," Homendy said. "It is meticulous work, but because we do that, we get to the right solutions as part of our investigation."