How’s Your Situational Awareness?

Tenth Anniversary of the USS Greeneville Collision 

The USS Greeneville – SSN 772

Wednesday February 9th marked the ten-year anniversary of one of the most inexplicable marine accidents in modern history.  The USS Greeneville, a fast attack submarine, struck the Ehime Maru, a Japanese flagged vessel in the waters off Oahu.  Nine people on the Ehime Maru were killed.  It’s a unique story of the extreme importance of situational awareness and how it can be lost through poor communication and artificial pressures.

The Greeneville, with a crew of 106, 16 civilian VIPs and the Chief of Staff COMSUBPAC, left Pearl Harbor for a show-and-tell which included a tour, lunch with the skipper, and maneuvers including an emergency surfacing drill.  They were due back to Naval Station Pearl Harbor by early afternoon.  While underway, VIPs were on the bridge, in the control room and some steered the ship under close supervision.

Tracking Contacts

Surface and submerged contacts are tracked using a system where the sonar team interacts with the fire control team.  The fire control team does target motion analysis: speed, heading, etc.  Together they work to monitor and assess contacts: whether a ship’s bearing has them “closing” or “opening” with the sub.  Part of pinpointing a target’s course is dependent on the sub making turns to provide new angles for evaluation and to clear their “baffles”, the area astern of the vessel where tracking is impaired by propulsion noise and they are acoustically deaf.  That day, personnel were tracking three or four contacts, described as “a light workload”.  Crews were routinely used to tracking 20 or 30 and occasionally 40 contacts at once.  First contact with the Ehime Maru was at 12:32.

Afternoon Maneuvers

Lunch ran late causing the maneuvers to start behind schedule. There were conversations between members of the crew, including the Commanding Officer (CO), about a late arrival at Pearl or whether they should cut the cruise short. The CO said that he would push his Officer-of-the-Deck (OOD) presumably to make up time. It is hard not to conclude that time pressure helped lay the groundwork for what followed. A Navy Board of inquiry termed the CO’s behavior as creating “an artificial sense of urgency.”

Around 13:00, 16 visitors entered the control and sonar rooms and the sub commenced a series of high speed turns and depth changes.  During this period and later, the CO failed to allow the OOD to drive the ship and was “overly directive” in the words of investigators.  He seemed to step in and out of the picture.  Crew would later report they did not have a good read on surface contacts before beginning maneuvers.  The OOD had not ordered course changes to improve the target analysis and the CO was not aware of that fact.  (At 12:40 a “baffle clear” was conducted where the Greeneville turned to a heading of 240 degrees.  It actually put one of the contacts in their baffles negating the purpose of the procedure.)  The CO also did not review the plot chart being kept by the navigation team.  There was little communication between the CO and OOD.

The Greeneville had lost situational awareness and communication in the control room and with the sonar room was largely ineffective.

Crew members gave multiple examples of how the large number of visitors interfered with normal operations, hindered their ability to see instruments, make needed updates and move about the control room.  The total number of people (crew and VIPs) in the control room was estimated to be, at various times, between 25 and 30.  At battle stations there are 31 crew members in this area.

The Move to Periscope Depth

At 13:31, the CO ordered 1) preparations to go to periscope depth and 2) that they should be there (at 60 feet) in five minutes.  These commands violated the CO’s own standing orders.  The artificial deadline resulted in the CO and the OOD failing to complete standard operating procedures, a key goal of which is to gain an accurate picture of all contacts before approaching the surface.  Fire control personnel felt rushed trying to finish their tasks. One of them had adjusted his solution for the Ehime Maru from an opening to a closing target and from 16,000 yards to 4,000 yards, both correct assumptions.  The lines on his screen began to converge, an indication of an accurate reading, but he missed that fact.  The Ehime Maru was only about 2,500 yards away moving generally southbound at 11 knots.

Tomorrow – Part Two:  Collision at Sea.

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Also on FireGeezer…

• How’s Your Situational Awareness? (Part 2) – February 11, 2011