Thread by @propublica

In the early hours of Aug. 21, 2017, the USS John S. McCain took an unexpected left turn & collided with a tanker. 10 sailors lost their lives.

In an internal investigation, the navy blamed the destroyer’s crew.

But that’s not the whole story. Not even close. (THREAD)

2/ We recreated the events leading to the crash. It happened fast. Only 3 minutes and 19 seconds. Was it solely the sailors’ fault? Or did the fancy new technology set them up to fail?

3/ We join the McCain 20 miles from Singapore, while the crew was navigating one of the world’s busiest shipping lanes. The 23-year-old at the helm was steering with the new touch-screen navigation system called the Integrated Bridge and Navigation System, or IBNS.

4/ The captain was on the bridge to assist in the complex maneuvers ahead. He ordered one sailor to take over steering while another sailor controlled speed. The idea was to avoid distractions by having each man focus on a single task. Here’s what the controls look like:

5/ Let’s pause to talk about how this is supposed to work. It’s important to understand that the captain of the ship had put the new system into backup mode, giving him greater control over navigation but removing some safeguards.

6/For example, normally when transferring steering between terminals, both users must press a button to acknowledge the change.
In backup mode, only 1 user has to press the button. This caused confusion about who had control over steering & thrust. Here’s what they're looking at:

7/ A panel in the top left corner of each screen displays who has control of steering, but for new sailors and those not fully trained on IBNS, this might not be clear.

See for yourself how small that box is:

8/ When the sailor who was **supposed** to be controlling the steering went to test the wheel, the rudder didn't respond because control of steering had been transferred to the other terminal.

“Loss of steering,” he called out, believing there was a malfunction in the control.

9/ This created a problem with the transfer of the thrust controls.

Each of the ship’s two main shafts needed to be transferred to the other station, but this process was interrupted by the “loss of steering” call.

Instead, only control of *one side* was transferred.

10/Meanwhile, the McCain was drawing closer to the path of the 600-foot commercial shipping vessel.

11/ When control for both shafts was finally transferred, they were no longer in sync.

So when the sailor attempted to decrease speed, only one side decreased. It was like being in a rowboat with one side pulling harder.

12/ With the throttles not in sync, the McCain veered sharply to the left and toward the path of the tanker.

Nobody knew who was in control of the ship. It was time to press the big red button.

13/ Pressing the big red button on the control panel overrides everything else and sends control of the ship to the station that pressed it.

14/ It seems straightforward, but not everyone knew what the big red button *actually did.*

Some sailors *believed* that pressing the big red button transferred steering specifically to the rear station.

15/ Those sailors heard the order, pressed the button, and thought they had sent control to the correct location.

Instead, they had transferred it to themselves.

16/ After swapping control 3 times in under 30 seconds, the correct crew members were finally in charge of the ship’s navigation, but it was too late. Within seconds, the McCain crossed in front of the tanker, whose bow crashed into the Navy ship’s port side.

17/ In an internal investigation, the Navy did not address how the design of the steering system may have contributed to the fatal accident.

18/But in response to emailed questions, Navy officials said they had taken steps to fix the “complex touch-screen controls” of the navigation system. They said they had improved training on the system throughout the fleet.

19/ We’ll be dropping another big navy investigation *really* soon. Sign up to get it in your inbox:
go.propublica.org/bigstory-social