NTSB Reports on the Cause of the MV Dali Hitting and Collapsing the Bridge in Baltimore

On today's episode of What's Going On with Shipping, the NTSB reports on what caused the motor vessel Dolly to crash into the Francis Scott Key Bridge.

I'm your host, Sal Maglano.

Welcome to today's episode. So, November 18th, 2025, the National Transportation Safety Board is hearing from its investigators today about the crash that took place on March 26, 2024 that resulted in the collapse of the Francesc Key Bridge, the killing of six road workers on it.

And today, the NTSB investigators are laying out what they have found that transpired that day on the ship. I want to do a brief synopsis that covers the moment from when the ship lost power until it struck the bridge because there's some new evidence that comes out in this and some fuller descriptions and details.

Plus, I I want to comment a little bit on the testimony. I've been watching it all day.

It's it's it's it's wrapping up toward uh evening now, but I want to hit on a couple of key factors that I think maybe not hit enough or emphasized enough by the NTSB investigators.

Matter of fact, it took the chairman and the board members to kind of pull some of this out.

So, if you're new to the channel, hey, take a moment, subscribe to the channel, and hit the bell so be alerted about new videos as they come out.

Now, we've covered the dolly quite extensively here on what's going on with shipping.

From the very first morning when the incident happened all the way through the event, we have discussed uh multiple issues uh regarding the dolly and the events. But today, I really want to break down for us what the investigators have found. So, this is the board that is hearing the testimony.

Jennifer Homde who is the chairwoman of the National Transportation Safety Board and two of its members Thomas Chapman and Michael Graham. These are the investigators that presented before the board today.

But in particular, I want to focus on the testimony of Captain Marcel Muse who provided I think the the best kind of blowby-blow second by second analysis here. But I'm going to throw in stuff that has been testified on by other members and really pull the string on some of the events that Captain Muse talks about, but I don't think in enough detail at the time.

So, let's go ahead and break this down for you.

This graphic displays the ship's power management system.

Glowing yellow parts represent online machinery or live electrical circuits.

The dolly was propelled by a single slow-speed 57,000 horsepower diesel engine which was directly connected to a propeller.

A vessel's rudder was moved by rams and up to three steering pumps. So this is from the report done by the NTSB.

This shows you on the left a view of the dolly's main engine looking aft looking back toward the back of the ship.

So you're above here. you're from uh basically on the platform where the engine control room is, the engine control room is in a sealed space away from the noise of the machinery.

And then two decks down behind the engine. This is your view looking forward.

So here's the engine right here in the center. You can see this large shaft right here. That is the propeller shaft that's going down.

Now this is two decks above where the main engine is seen on the left.

That's going to be important later on when we start talking about a flushing pump.

>> The ship's electrical power was supplied by four diesel generators.

The diesel generators were connected to a high voltage main electrical bus that directly powers certain shipboard equipment, including the main engine lubricating pumps, the bow thruster, and refrigerated containers.

>> So, real quick, want to talk about the bow thruster for a moment because this does come up during the uh testimony.

The bow thruster is only useful for the ship under three knots. Uh the ship is going to hit the bridge at anywhere between seven and eight knots.

So even though you do have power for the bow thruster at certain points during this 4 minutes, the bow thruster provides you no useful power uh to move it.

It's designed to help and assist you maneuver the vessel on and off of birth.

It's really not designed to steer the vessel or give any sort of course assistance while underway on power.

>> The dolly had a low voltage bus which is powered from the high voltage bus through a pair of redundant step down transformers depicted here as TR1 and TR2.

>> So those step down transformers are really important.

So the ship is operating off TR1. TR2 is kind of the backup.

One of the things that they noted in the testimony was that the low voltage step down transformers were set to manual.

Meaning that you you basically have two configurations here.

Either manual or automatic. If you are on automatic when you lost power across one of the transformers, the other one would kick in. You would basically transfer transfer the power across that transformer.

In this case, they're on manual.

And as noted here, the configuration was left to the ship's crew.

There was no company or regulatory requirements to be in automatic.

So, it's not that we're dinging the crew here at all. It's just noting the configuration of the system.

>> The low voltage bus supplied electrical power to Dolly's remaining equipment and services, including the steering gear, main engine cooling water pumps, fuel oil pumps, and vessel lighting.

So the low voltage bus is going to be key because when you lose the low voltage bus, you're going to lose power to certain key systems on board the ship.

And when that HR1 breaker trips and now all of a sudden you don't have power going to the low voltage bus, that means you're going to lose essential systems and some systems that should not be an issue, but they are because of the way this ship is configured. The vessel was also equipped with an emergency diesel generator which was designed to start automatically following a blackout and supply power to the emergency bus and some critical systems. The components and circuits shown here that are glowing yellow show the configuration of the vessel as it got underway prior to the accident.

Generators three and four were running and powering the vessel.

The bow thruster was on but was not being operated.

The low voltage power was being supplied from step down transformer number one. About 0108, the ship entered the Fort McHenry channel.

The senior pilot let the assist tugs go and as the ship lined up in the channel, he turned the con over to the pilot in training.

Speed was then increased to slow ahead.

All of that is very routine.

There's nothing out of the ordinary there.

Uh you would usually use the tugs just to get you on and off the birth which additional.

They do not accompany or escort you out of the port of Baltimore.

Again, there are ports that do require that, but not Baltimore.

And more importantly, it's not just a matter of having the tugs follow you.

They need to be hooked up and they need to be of sufficient size to be able to do something.

When you have a 100,000 ton ship propelled at 8 knots going down the channel, the two pilots on board, fairly standard at the time. You have a pilot in training and then you have the senior pilot.

Turning over to the pilot in training, very routine.

Again, that pilot, while it sounds like maybe somebody new, it's not. They have years of experience.

uh becoming a pilot takes a long time and and believe me uh what the pilots do in this scenario and what happens here is top-notch performance by them.

>> At 0125 as the ship approached the intersection of the Curtis Bay channel with the Fort Mckenry channel breaker HR1 unexpectedly opened the ship and the ship experienced a low voltage blackout.

As a result, the vessel lost steering, the ability to operate the bow thruster, and most of the vessel's lighting and equipment essential for operations.

>> So, it's at this point I would explain what caused that power outage.

Now, they do go into detail talking about it here in a minute, but I'm interject here because I think it's important to say what it is, and it's very simple.

It's it's a loose wire, believe it or not.

a loose wire, a poor connection creates an undervoltage that triggers the uh breaker here to trip the HR1 breaker to let go.

Uh under voltage, not enough voltage going across the breaker that causes it to open it up. And the reason for the loose wire is is really incredible.

So this is the engine control room on the dolly. Uh what you tend to look at here is the panels.

These are the electrical panels.

This is probably looking toward forward side of the ship.

uh looking after you would be looking out over that main engine that you saw, but it's an enclosed room, so it's soundproof, so it's not as loud as being in the engine. But inside these panels are just circuits after circuits.

And these control circuits have these terminal blocks in them. And what you do is you plug these wires in and it allows you to connect switches together.

So you're not splicing wires together and you're using this as kind of creating a series of switches. And what you see here is they're all plugged in.

And they have these blue caps that allow you with numbers to match where they need to go.

Now, in the case of the dolly, what happened is the fereral, the part that goes inside that terminal block was obstructed.

So, this video here kind of takes you in. So, you take these wires and you put the fereral in and it kind of snaps and locks into place.

Uh, what you do is you use a small tool to kind of spring open the locking mechanism.

You put the wire in. If you ever used kind of an automatic splicer or something like that, what you do is that fereral there, that blue cap kind of locks it into place. So, it's all the way in.

You've got enough wire in there to make your connection.

Well, the problem they had in the case of Dolly, is that the label should be above the fereral.

But in the case of this wire, what they're calling wire one, they found that the label had actually gone over the fereral. Now what that does is it prevents the fereral from going fully in and locking into place. So in this cutaway kind of the same thing.

You spring this open and what they found was a wire that was not fully inserted in because of the label and said you got a very loose connection. And what they determined was that during tests they found this wire that was loose and they replicated it and they did it again and again and again and they found the same thing happened.

It created an undervoltage to the HR1 circuit and it opened up the breaker and it depowered the transformer going to the low uh voltage uh bus board. Now I I don't know what this wire does. Uh they never go into detail about it. They just call it wire one.

What they noted is that synergy required inspections but really no practical guidance. That there are thousands of these signal wires and terminal connections and that checking each by hand is just too labor intensive and and a challenge. And that if you manually manipulate them, you can cause this premature failure is like what happened here.

And so I think one of the issues here is is how you do it.

And they talk about the idea of using thermal imaging cameras to find the connectors to do a more thorough inspection to find it. Again, I really want to know what this wire did because it's kind of disturbing that one wire triggered this, but that seems to be what they have found.

>> 8 seconds later, the cooling water pumps essential for the main engine to operate shut off due to the low voltage blackout.

>> And when that cut out, the main engine triggered it to shut down and the engine began to spiral down. Remember, this is a slow speed diesel engine.

The engine is directly connected to the propeller shaft and the propeller. So that when the engine slows down, that's it.

The prop comes to a a halt. It just stops.

There's there's no transmission, no flywheel.

It's going to stop right then.

Now, according to what they found, the main engine was configured to shut down on a low cooling water pressure.

The automatic shutdown was a classification society rule that was put in place at the time of the vessel construction.

However, it is no longer required.

So, the engine is designed to protect the engine.

If you don't have cooling water going in, the engine sits there and says, "Oh, I may get damaged if I don't have cooling water. I'm going to shut down.

" Even though there is a cooling water tank above the engine that can free flow water in, that is not enough for that engine. That engine's going to shut down.

Now, the main engine was needed to operate and effectively steer the vessel because the ship was in shallow water.

When you lose propulsion of the vessel, uh you need the thrust, you need the wash from the propeller going past the rudder to give yourself uh the ability to steer the ship.

And unfortunately, this system did not have a redundancy that was built into it.

So that number one, you can turn that off so that the you can run the engine.

You could run the engine without cooling water.

you were obviously going to damage it just like any other engine, but at least you would have it for a period of time until uh you got past the bridge, but again, that system was in place.

You had the automatic shutdown all set.

>> The main engine as well as the bow thruster remained off throughout the remainder of the casualty. At 125 and 58 seconds, almost a minute after breaker HR1 unexpectedly open, causing the blackout, the vessel's engineering crew manually closed breaker HR1 and LR1, restoring low voltage power.

So, the crew, when the power goes off on a ship, you have emergency lighting.

Emergency lighting comes up. They're looking at the board in the ECR, the engine control room, and they've seen that, okay, the HR1 has tripped, and what we need to do is kind of reset it. Now, they don't know what caused it to trip.

Now, this is the other thing.

The underlying cause, that loose wire is not known at this moment.

But what they did is, okay, we're going to reset everything, get back to where we are. This should give us power back to the low voltage uh bus board, and hopefully we can start a main engine restart and get the main engine buck back up online. According to uh testimony today, that's about a 30-se secondond process, but again, you have to have everyone in place to do that.

Uh, and I don't think everybody's in place at that moment to do a main engine restart.

I think it's going to take a little bit longer than that to do that.

But as you're going to find out, when they lost the low voltage bus, they're going to lose some key systems here.

Much of the equipment that had shut down with the initial loss of low voltage power began to automatically restart, including most of the vessel's lighting and steering gear pumps.

The electric pump supplying the fuel to generators three and four was not capable of restarting automatically following the restoration of power and remained off.

To restart this pump, a crew member had to do so manually from a local station.

Okay, I I this is the part that got me. I not going to lie.

I I literally was kind of screaming at the screen at the moment this happened.

This is one of those elements right here where okay, a loose wire that's going to happen on a ship. It's going to be really hard to find. thousands of wires worked its way loose over 10 years.

I mean, there's no telling. This is the one that gets me because those motors, the generators three and four should get fuel to them automatically. The pumps to them should start automatically.

However, in this case, this crew has done something to bypass those pumps.

So, later in the presentation, this comes up.

The configuration of flushing pump as a service pump.

So diesel generators 3 and four were supplies with fuel from a single fuel pump.

The flushing pump stopped when power was lost.

Now what's a flushing pump?

It's exactly what it sounds like.

You use this pump to flush out fuel lines.

When you're operating within the waters of the United States, you're in what's called an environmental control area.

You have to burn clean fuel, either marine gas oil or very low sulfur fuel oil or high sulfur fuel oil. But you run that high sulfur fuel oil through a scrubber.

In the case of Dolly, engines three and four, generators three and four are not configured to the scrubber.

So you either have to run low sulfur fuel through it or marine gas oil.

They're running marine gas oil through it.

However, to run the marine gas oils to engines three and four, if you use the normal fueling system, you've got to clean out the high sulfur fuel.

You've got to flush it. You've got to get it out.

That takes time, effort.

There's there's a lot involved in it.

What the crew on the dolly did and not just Dolly because they find out that this actually was took place on another ship operated by Synergy.

They set up this flushing pump.

This flushing pumps directly marine gas oil, the clean oil, the clean fuel directly to just generators three and four.

The problem with this system is number one, there's no backup to it.

Second, when they lost power on the low voltage uh busboard and then they got it back up, the flushing pump did not have an automatic start. So, the pump's not able to start. To get it to start, you've got to send a crew member two decks down to the flushing pump and start it automatically. And this thing does not meet classification requirements at all. Now, they went in and talked about the fact that, you know, Synergy, the company operates Dolly, should have oversight over this, although they note that Synergy was unaware of the use of the flushing pump.

I have my doubts about that. I I really do.

I don't think so. They said they found it on another ship. I think this is rampid throughout them.

They're doing something to get away. And again, it just saves them time.

They're basically bypassing the normal fuel pumps and using this flushing pump to save time, clean up effort. It's just designed in an inappropriate way. It doesn't have backups and most importantly, it's not meeting the classification society.

I am sure the classification society would be aware of this or else the crew would take this system down when they went through their reclassification.

>> Generators three and four remain running by consuming the remaining fuel in the supply line.

The ship was closing with the bridge at 8.6 knots.

The vessel developed a starboard rate of turn of 4 and a half degrees per minute and a senior pilot gave a port 20 degree rudder command.

He also called his dispatcher by cell phone and requested the bridge be closed to vehicle traffic.

He then called for tug assist by radio.

So, a couple of things on this statement here that's really fascinating.

Number one, the procedure for calling about closing the bridge had just changed 20 days before this event takes place.

The procedure had been to call the dispatcher and then the dispatcher will call the Maryland uh transportation authority and the Coast Guard. They changed that and they said, "No, you call directly the Coast Guard and then the Coast Guard will do it." Well, the pilots didn't do that.

They called directly their dispatcher.

Fortunately, they did because the dispatcher was able to immediately get up with the Maryland dispatcher.

They were able to shut traffic down on the bridge.

Unfortunately, they could not get the alert soon enough to the road crew and seven of them go in the water.

Six of them eventually drowned. The other thing that you start seeing here is the ship begins its swing to the right to starboard.

And there's a reason for that.

When the ship was above this point in the track, it's in the channel.

It's in the Fort McHenry channel. And as the ship goes through the channel, the bow pushes water away from it. It creates a positive cushion against the banks.

And that's pushing against the bow.

It keeps you in the center. But when the ship got closer to the bridge on the right side of the vessel, the the the starboard side of the vessel, what happens is you open up the water here, because there's a channel that goes from east to west here.

It's the Curtis Bay channel.

What that means is there's no more force acting on the starboard bow, the right bow of the vessel. instead all the force is on the port bow which means if you're heading straight and all of a sudden you have open water off to your right the ship is going to head into that open water because it's getting pushed off the bank there. At the same time the propel the ship starts to pivot a little bit about a quarter to a third of the way after the bow. The stern starts getting a little bit closer to the bank and the stern wants to grab the bank.

It wants to actually suck in.

It's called bank suction. Wants to pull in.

So the ship begins its turn.

Everybody talks about that turn they see in the video.

That's what's causing the turn at this point.

>> Sensing the loss of power to the emergency bus, the vessel's emergency diesel generator automatically started and powered the emergency bus at 126 and 10 seconds.

Okay, here we have another incident with this ship that doesn't go according to plan. So, an emergency diesel generator provides power for essential systems. Cannot run the ship.

It's like a basically a big truck generator, big truck engine.

uh maybe for a larger truck, but that's what you have here.

Regulations say it's supposed to start in 45 seconds. This one didn't start for 70 seconds. Now, it was in a standby start configuration.

However, what they noted on the ship on the dolly specifically is that the radiator damper position could prevent the generator from starting.

And that's what seems to be the case here. It didn't allow the generator to start in the required 45 seconds.

This provides you emergency lighting.

It provides you navigation lights and more importantly, it gives you power to one of the three steering motors for the ship. Now, you don't have full steering, but at least you have some steering.

But when the power went out and the emergency generator does not come on for 70 seconds, there's a block period of time there, 70 seconds, where there is no power to the rudder at all.

As the fuel pumps for gener generator 3 and four had still not been manually restarted, what fuel remained in the supply line was insufficient to keep the two generators running, and the generators began to stall.

Sensing the underperformance of generators three and four, the vessel's automat automated power management system automatically started standby generator number two. 66 seconds after the low voltage power was initially restored and before generator 2 could come up to speed and connect to the high voltage bus, the power management system disconnected generators three and four.

So you've now disconnected generators three and four cuz they're sputtering.

They don't have fuel. You're getting low voltage out of them. And so the power management system once again trips the breakers HR1 LR1. And now there's no power going to both the high voltage bus and the low voltage bus. So, it's a different reason for the second blackout.

The first one was the loose wire.

Now, it's because generators three and four are not getting fuel because they're using that flushing pump to put fuel into the motors to bypass the normal systems. >> This resulted in a second blackout.

This time, both the high voltage and the low voltage buses blacked out.

The emergency generator continued operating and powered the emergency bus through the second blackout, which supplied power to some of the vessels lights, navigation equipment, and a single steering pump.

3 seconds later, at 127 and 7 seconds, generator 2 reached a rated speed, and the power management system automatically connected it, repowering the high voltage bus.

One diesel generator alone could run all of Dolly's power at needs. At this time, generators three and four remain running in a degraded state and were unavailable to be connected. On the navigation bridge, the pilot ordered the port anchor let go and increase the rudder command to hardport or 35°. So, a couple of things there. A question about the anchor.

There is no anchor that's going to stop you. Understand anchors are designed to hold a ship in place when it's not designed to stop a ship going at 8 knots. No, you've seen the battleship, the movie battleship with the battleship Missouri. That's not the way it works. Number one, you have to drop that anchor from the anchor.

You don't do it with a button up on the bridge.

Second, it takes you a little bit of time to get that anchor dropped.

Third, it's just not going to stop you.

It's going to bounce along the side.

Granted, there's something you got to do, and they're going to go ahead and drop the anchor, but in truth, it is not going to do much. They're trying to do anything they can to slow down this vessel and get it to shear away from that southern pillar. And that's why they dropped a port anchor.

>> At 127 and 36 seconds, the vessels engineering crew manually closed breakers HR2 and LR2, restoring power to the low voltage bus this time through step down transformer number two.

So many people are going to want to second guess the crew on board. Why didn't they do this immediately? Why didn't they open up uh transformer 2 earlier?

Open up HR2 and LR2. Again, you've got to practice that.

You got to be in the habit of doing that. And again, one of the statements that's made during this hearing, which I find I unconvincing is that that they only switched over between these two like twice a year.

I I I mean, when I sailed, and granted that was a while ago, you know, we would do shift overs of power weekly. And I'd be love to hear from comments of people what they do on their ships because I think if you're only doing this once every six months, it's one of the problems they had here.

It's probably why you have a loose wire that you never found before.

Second, it gets your crew out of the habit of doing this in efficient manner.

Now, granted, it's not that hard to do it. You just got to throw switches to do it and close those breakers.

However, it you've got to train on this so that it's instantaneous.

You go through the motions without even thinking about it.

I train firefighters. I'm telling you right now, if you don't train the way you execute, you know, your mission, then it it becomes a problem because you got to think about it. You need this to be muscle memory when it happens.

Again, similar to the recovery from the initial underway loss of power, much of the equipment that had shut down due to the second loss of power began to automatically restart, including most of the vessel's lighting and two additional steering pumps.

Unlike the fuel pump for generators three and four, which required a manual restart, generator 2's fuel pump was set to automatically restart following the restoration of power.

The ship was now on a heading of 155, 1,200 ft from the bridge and closing at 7 and a half knots.

>> 1,200 ft. This ship is just about 1,000 ft.

I I mean, you're not going to be able to do anything. I again, I did that video on the 4 minutes and I can't tell you the bottom of my heart sinks when I I think about the crew on the ship and the people up on the bridge about what is about to happen here because there there's no force on the planet that's going to stop this ship from maneuvering.

The only thing that could have prevented it was keeping power on, having some sort of maneuverability and control of the of the rudder and and keep that main engine up and running.

Uh it's just there are too many forces acting on the ship that is not hurling it toward that southern pillar at this moment.

>> The rudder was hard over which had little effect without any propulsion.

The right southbound lane of the bridge had previously been closed and MDTA officers were stationed on either end of the bridge to assist with traffic.

About this time, they were told of the emergency and instructed to close both ends of the bridge to all traffic.

About a minute before the contact, the crew manually restarted the fuel supply pumps for generators three and four.

The generators returned to a normal speed.

displayed is the configuration of the system when the ship made when the ship contacted the bridge at 129 and 9 seconds.

>> So note that configuration.

Generators three and four are back up and running, but they're not up to speed yet providing power.

2 is providing power for the vessel.

The emergency generator is up and running.

They're going through the step down transformer number two. Number one is not being used. The bow thruster is not energized and the main engine is offline.

And again, you know, this happened in the span, we've taken about 30 minutes to go through this.

This happened in the span of four minutes.

Four minutes. And that's the situation that crew found him in. And it's just absolutely horrifying to think that in four minutes, that's what transpires.

And again, you know, I I I got to come back here and say a lot of things that this crew and this company were doing should be raising red flags.

uh they were trying to get some shortcuts and workarounds and disturbingly enough these were not found.

The classification society did not ping them for it.

Maybe they hid them from the classification site.

We don't know. Port control, the US Coast Guard that goes on board to do their inspections did not find it.

Tough to find. These are not easy find, you know, things.

You're not going to find a loose wire out of thousands of wires.

The flushing pump, I don't know how they had it rigged and how they had that configured.

That would have been a tough one to find unless you knew the configuration of the vessel.

Uh this ship and crew were doing a lot in the company to get around laws and unfortunately what we have is this accident transpire.

It's why we need to be thinking about more safety in and around our harbors. Uh reinforcing our infrastructure, maybe thinking about these these escorts for ships going in and out.

What are we going to do to ensure that we have safe operations so that we don't have a tragedy like this again?

shut the port of Baltimore down for two months. The 11th 12th largest port in the United States, 2 to 3% of US imports or exports. What happens if this happens in LA, Houston, Savannah, New York, New Jersey, be catastrophic to the economy, let alone to the number of people who could be hurt or killed.

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Hope to follow up with some more videos on this.

Going to finish watching the entire hearing.

Uh it's a lot today and hopefully when the report comes out we'll have some more further information.

until the next episode