HRO 9j Collision at Sea-Sequence of Events7
This post finishes the analysis of the order given by the Commanding Officer (CO) of the USS JOHN S MCCAIN (DDG 56) (JSM) to add an additional watchstander for ship control as the ship was entering the Singapore Strait Traffic Separation Scheme (TSS). It provides a short summary of the events that occurred from the time watchstanders began to execute the CO’s order until the collision. I abbreviated the reference details to conserve space. Refer to the original post for the complete information.
References
(a) Navy Report of the Collision https://www.doncio.navy.mil/FileHandler.ashx?id=12011.
(b) National Transportation Safety Board (NTSB) Report of the Collision https://www.ntsb.gov/investigations/accidentreports/reports/mar1901.pdf
(c) International Rules of the Road https://en.wikisource.org/wiki/International_Regulations_for_Preventing_Collisions_at_Sea.
(d) U.S. Navy Regulations, Chapter 8, https://www.secnav.navy.mil/doni/US%20Navy%20Regulations/Chapter%208%20-%20The%20Commanding%20Officer.pdf
(e) Standard Organization and Regulations of the U.S. Navy, OPNAVINST 3120.32D CH-1, dtd 15 May 2017, https://www.secnav.navy.mil/doni/Directives/03000%20Naval%20Operations%20and%20Readiness/03-100%20Naval%20Operations%20Support/3120.32D%20W%20CH-1.pdf
Sequence of Events (continued)
In the prior post, I averred that an order has three parts observable by outsiders:
the context in which the order was given (what was going on at the time),
the order itself, and
how the order was carried out (the focus of this post).
In the prior post, I discussed the first two parts. Throughout my analysis of the collision between the JSM and MV ALNIC, I have scrupulously avoided labeling any of the things people did or decisions they made as “errors.” In my analysis of the collision, there are no errors, only actions. The reason for this is my belief that labeling someone’s actions as an error afterward doesn’t help you understand why those actions made sense to the actor at the time (Dekker, 2004). Understanding how the CO and watchstanders on the Bridge of the JSM made sense of the situation is not possible because of the way the post-accident reports were written. That’s not an error either.
* Dekker, S. W. A. (2004). The hindsight bias is not a bias and not about history. Human Factors and Aerospace Safety, 4(2), 87-99.
In my description of the context in which the CO gave his order between 0519 and 0520, I described what an experienced Surface Warfare Officer in the U.S. Navy could observe by being on the Bridge of the JSM. The personnel on the Bridge of the JSM were likely aware of the context: entering the Traffic Separation Scheme (TSS) in the dark, very close to the ALNIC and other ships, overtaking the ALNIC at twice its speed. We have no idea how they actually *processed* this information (i.e., what they thought about it).
For the second part of the CO’s order, the accident reports don’t tell us *how* he gave the order to the OOD to change the configuration of steering and engine control (ref (a), p.46). For my analysis, lacking the details of how the CO gave the order (i.e., whether he specified how and when to carry it out) doesn’t matter. I am not the lead accident investigator. I am just trying to learn from the information contained in the accident reports.
The third component of the CO’s order was how it was carried out by the watchstanders. What mattered now was not just that the new watchstander configuration required a change in rudder and engine control mode in the middle of overtaking another vessel at close quarters at twice its speed while entering the TSS in the dark. I believe the most important thing at this point was the decision to execute the CO’s order at that moment. Even if the CO insisted that his order be carried out immediately, this decision normally belongs to the OOD. Unfortunately, we can’t learn anything about the OOD’s decision about how to carry out the order from the reports. Both reports focused instead on how Bridge watchstanders changed the configuration of the Ship Control System (SCS), which I believe is much less useful from a High Reliability perspective.
With the the port and starboard shaft synchronized (“ganged”) and producing revolutions (RPM) for a ship’s speed of 18 knots (kts), in the roughly four minutes that elapsed between beginning to carry out the CO’s order and the collision, the following major events occurred:
The Boatswain’s Mate of the Watch transferred control of the port shaft to the Lee Helm control station. This unsynchronized the shafts (“unganged” them) in accordance with normal system programming.
Seconds later, steering control was transferred to the Lee Helm, causing the Helmsman to report a loss of steering because his control station no longer operated the rudder. No one knows how this happened and there was no evidence of a system fault.
Displays for both the Helm and Lee Helm would have indicated that the lee helm station had control of steering, but the Helmsman, Lee Helmsman, and BMOW did not report observing this (p.25, ref (b)).
With the crew focused on the reported loss of steering, no one on the Bridge was aware that the Lee Helmsman only had control of the port shaft.
With the ALNIC on the port beam of the JSM, the ship’s heading changed 13 degrees to port, toward the ALNIC. This was not a malfunction.
Contrary to the JSM’s Loss of Steering Standing Order, the OOD ordered the Conning Officer to reduce the RPM of both shafts to produce a speed of 10 kts and not bare steerage way.
Only the port shaft RPMs were reduced because the shafts were still not synchronized. The starboard shaft continued rotating the RPM necessary to produce 18 kts. This discrepancy was not noted by Bridge watchstanders.
The After Steering control station, the location of steering system motors and other components, took control of steering in response to the CO’s order to do so.
Seconds later, the Helmsman transferred steering control back to the Bridge. This was not what he intended, but it was the proper system response for the button he pressed.
The Helmsman reported that he had control of the rudders.
The CO ordered the the Conning Officer to turn the ship right, away from the ALNIC.
Thirty seconds before the collision and before the Helmsman could comply with the order to turn right, watchstanders in After Steering again took control of the rudders to comply with the CO’s previous order. The rudder input signal at the After Steering control station was 33 degrees to port.
Bridge watchstanders reported seeing the rudders move to 15 degrees port before After Steering changed the rudder input to 15 degrees to starboard.
The JOHN S MCCAIN crossed in front of the ALNIC and was struck by its bulbous bow at the waterline aft of midships on the port side. The destroyer’s hull was breached, causing flooding in several spaces, including berthing areas where Navy sailors were sleeping.
“From the time when the CO ordered the Helm and Lee Helm split, to moments just before the collision, four different Sailors were involved in manipulating the controls at the SCC” (p.59, ref(a)). The collision caused the death of 10 sailors in a berthing compartment located near the impact point on the JSM. 48 others were injured. There were no injuries aboard the ALNIC.
