The guided-missile destroyer USS Fitzgerald collided with the ACX Crystal merchant vessel Saturday morning off Japan.
CNN  — 

Whether it’s an aircraft carrier or any other warship, a United States Navy vessel never sleeps on the open sea thanks to a complex orchestra of people and systems tracking its course.

A deadly collision Saturday between the USS Fitzgerald and a container ship off Japan’s coast raises questions about how military vessels operate. Here are the basics:

How does a Navy ship navigate?

Service members rely on a constant flow of information from satellite technology, radar, the Global Positioning System and visual cues to track their course and monitor other vessels. Ships receive normal weather updates and imagery from satellites but no real-time imagery of ocean traffic is available.

How much attention they pay to each signal depends on the situation, said CNN national security analyst John Kirby, a retired rear admiral in the US Navy.

Vessels approaching shore or heavy traffic use more feedback to adjust position minute to minute, he said. As a vessel gets farther out into lighter traffic the crew uses less feedback to modulate its position.

“It’s a multifaceted, multilayered application of a series of sensors in real time that are providing feedback not only about where your ship is but where other ships are,” he said.

On a destroyer, the information flows into the Electronic Chart Display and Information System, which interfaces with the ship’s GPS receivers and navigation sensors, such as speed and wind indicators, to give watchstanders a computerized real-time view of position and movement.

Who’s actually operating the ship?

Unlike merchant vessels, which may not necessarily be manned at the same level at all times, the bridge is staffed 24 hours. In a normal rotation, a typical bridge watch team consists of six to 10 members responsible for safe navigation and operation under the officer of the deck, who reports to the commanding officer.

The helmsman is a sailor who controls the direction of the ship based on orders from the conning officer. The quartermaster is the direct representative of the ship’s navigator who monitors the surface search radar system and other charts to provide a continuous navigational watch on the bridge. The boatswain’s mate of the watch is a petty officer who assists the OOD and ensures all bridge watch stations.

Below the bridge is the combat information center, a watch team of six to 10 officers and enlisted specialists responsible for the weapons system. The CIC includes a radar operator who monitors ships within range and a navigation chart plotter who also monitors the electronic chart display and navigation system.

Outside the ship, lookouts are typically stationed at the back and near the front on or close to the bridge. Part of the bridge watch team, their job is to constantly scan the horizon with binoculars as a backup to radar in case it misses a small fishing boat or picks up big waves in a heavy sea.

“Many times the radar picture may be convincing you of one thing and what you see doesn’t match up,” Kirby said. “You need an extra layer of context and you can only get that from what you can see.”

Everyone is in constant contact over different types of radio communications, some classified, some not, he said. To communicate with other vessels they use bridge to bridge radio, the maritime version of a CB radio, in which they pick up a microphone and find the common frequency to talk in real time.

What assistance does a ship have from any dispatch or central authority?

Higher headquarters maintain a regional picture of activity, tracking a ship’s progress and location. But once a vessel receives orders, it tends to be self-directed under the aegis of the commanding officer. He has “singular authority” over the vessel, making him a constant presence in the bridge, especially in busy environments involving high levels of feedback, Kirby said.

“Every commanding officer has full authority to defend his or her ship with weapons if he or she deems another vessel poses a hostile, direct threat to the safety and security of his ship and crew,” he said.

The commanding officer of the USS Fitzgerald was in his cabin when the collision happened, suggesting the immediate environment did not warrant his presence in the bridge, Kirby said.

“The captain would be on bridge if coming into port or leaving port or in a highly trafficked area, because it’s more dangerous,” he said.

“The fact that he was down in his cabin tells you this wasn’t that kind of environment.”

What sort of training is involved?

A lot. It starts at the US Naval Academy or Officer Candidate School and continues through an officer’s career, taking different paths depending on the person: classroom time, tests, simulations, on-the-job training on different warships.

Navy ship bridge teams in particular complete a management course that includes team-building and communications training, from situational awareness, analysis of error chains, voyage planning, stress and fatigue, among other skill sets.

“By the time an individual is standing watch on the bridge of a warship they have gone through an extensive amount of training and education and on-the-job experience to get to that point,” Kirby said.

Why don’t destroyers hit cargo ships (or vice versa) more often?

Because of all the precautions noted above, collisions involving Naval ships are uncommon, Kirby said.

“There is nothing the Navy takes more seriously than the safety and security of its ships and its sailors. Period. And, that’s why collisions at sea are so rare,” he said. “Do they happen? Yes. But it is exceedingly rare because the Navy takes safety and security so incredibly seriously because the stakes are so incredibly high.”

The commanding officer has several options if a cargo ship deliberately targets a destroyer – a rare scenario that Kirby suspects is not the case with the USS Fitzgerald. A vessel can change course or speed or fire a warning shot if the captain perceives a threat. It has happened as recently as January; the USS Mahan fired warning shots at Iranian boats as the vessels came within 900 yards.

What could have prevented the USS Fitzgerald tragedy?

It’s too soon to tell, Kirby said. Because the radio room was hit hard, the degree to which radio communications were used before and after the collision will likely come under scrutiny, he said.

Otherwise, he said one thing is certain. “The Navy will investigate completely and thoroughly and they will use what they learn in schools so it will never happen again.”