Two years after a devastating collision in Singapore that claimed the lives of ten U.S. Navy sailors and injured 48 more, the National Transportation Safety Board (NTSB) has determined that a lack of training was a key factor in the August 21, 2017 tragedy. Inadequate bridge operating procedures and a lack of operational oversight also contributed to the incident involving the USS John S. McCain, a destroyer, and the Liberian-flagged Alnic MC, a chemical tanker.

There were no injuries to the crew of the Alnic MC.

Where it happened

The collision occurred in the Singapore Strait, one of the busiest waterways in the world. In 2016 alone it accommodated 83,700 vessels of more than 300 gross tons. It occurred when the John S McCain – with a crew of 280 – and the Alnic MC were both headed towards Singapore in the westbound lane of the Singapore Strait Traffic Separation Scheme.

How it happened

As the John S McCain entered the Singapore Strait, steering and thrust were being controlled by a single watchstander – the helmsman – from the helm station. The commanding officer directed the lee helm station be manned as well and the crew took actions intended to transfer propeller thrust control from the helm to the lee helm station. The NTSB concluded that during the process of shifting thrust control, a John S McCain watchstander unintentionally transferred control of steering from the helm to the lee helm station, which resulted in a perceived loss of steering by the John S. McCain’s helmsman. In fact, steering control was available at all times in the accident sequence. The NTSB further concluded the unintentional transfer was possible because the system was being operated in backup manual mode, which removed a safeguard against inadvertent transfer of steering control.


The NTSB determined the probable cause of the collision was a lack of effective operational oversight of the destroyer by the U.S. Navy, which resulted in insufficient training and inadequate bridge operating procedures. Contributing to the accident were the John S McCain bridge team’s loss of situation awareness and failure to follow loss of steering emergency procedures, including the requirement to inform nearby vessel traffic of their perceived loss of steering. Also contributing to the accident was the operation of the steering system in backup manual mode, which allowed for an unintentional, unilateral transfer of steering control.

The NTSB also concluded in its report that the inability to maintain course due to a perceived loss of steering, the mismatch of port and starboard throttles producing an unbalanced thrust, and a brief but significant port rudder input from after steering combined to bring the John S McCain into the path of the Alnic MC. The decision to change the configuration of the John S McCain’s critical controls while the destroyer was in close proximity to other vessels increased the risk of an accident, according to the NTSB’s report.

Property damage resulting from the collision exceeded $1.2 M. There was no report of pollution associated with the accident.

Recommendations made to the US Navy

Based upon its investigation of the collision, the NTSB issued seven safety recommendations to the US Navy seeking:

  • Issuance of permanent guidance directing destroyers equipped with the Integrated Bridge and Navigation System to operate in computer-assisted steering modes, except during an emergency.
  • Issuance of guidance to crews emphasizing the importance of appropriate use of very high frequency radio for safe navigation.
  • Ensuring design principles in ASTM International Standard F1166 are incorporated when modernizing complex systems such as steering and control systems within the Integrated Bridge and Navigation System.
  • Revision of written instructions for bridge watchstanders on destroyers equipped with the Integrated Bridge and Navigation System to include procedures for shifting steering and thrust control between all bridge stations.
  • Revision of Integrated Bridge and Navigation system technical manuals to include a description of and procedures for ganging and unganging throttles.
  • Revision of training standards for helmsman, lee helmsman and boatswain’s mate of the watch for destroyers equipped with the Integrated Bridge and Navigation System to require demonstrated proficiency in all system functions including transfer of steering and thrust control between all bridge control stations.
  • Instituting Seafarers’ Training, Certification and Watchkeeping Code rest standards for all crewmembers aboard naval vessels.

The US Navy is acting on a number of its own measures to address safety issues identified in the wake of the John S McCain accident and other recent western Pacific region accidents.

Marine Accident Report 19/01 is available online at

Portions of Marine Accident Report 19/01 have been designated as Controlled Unclassified Information by the US Navy and those portions have been redacted.