The National Transportation Safety Board (NTSB) has published an investigation report regarding an incident where a pilot of a towing vessel on the Mississippi River left the helm unattended for several minutes, leading to a grounding near Thebes, Illinois on 29 July 2023.
The incident
On 29 July 2023, about 1449 local time, the towing vessel City of Louisville was upbound on the Upper Mississippi River pushing 11 barges when it grounded near mile 42.6, about 1.4 miles south of Thebes, Illinois. The grounding damaged the hull, flooding the engine room and the machinery and aft accommodation spaces. An estimated 30 gallons of gear oil were released into the river. There were no injuries. Damage to the vessel was estimated at $2 million.
Analysis
While the City of Louisville was upbound on the Upper Mississippi River pushing 11 empty barges, the towing vessel ran aground near mile 42.6 in a charted shallow and rocky area. The grounding caused fractures to the vessel’s bottom plating underneath the engine room, leading to water flooding into the engine room, machinery, and aft accommodation spaces.
The pilot of the City of Louisville was alone on watch in the wheelhouse when the grounding occurred. The pilot told investigators that, before the grounding, he had left the helm and was on the port side of the wheelhouse. He estimated he was away from the helm about 5 minutes. Leaving the helm unattended is contrary to prudent navigation practices when operating on rivers. The Mississippi River, in particular, has frequent turns, and the potential for strong currents and heavy traffic.
Due to these factors, inattention to a vessel’s path, even for a brief time, can result in encountering other vessels and hazards such as shallow areas or structures on the banks nearby. During the time the pilot said he was away from the helm, he missed a 9° course change to starboard on the sailing line (the recommended route). The pilot said that, before he left the helm, he checked the ECS. However, the ECS would have displayed the upcoming change in course.
Further, the pilot did not identify that the tow had begun to progress closer to the right descending bank while he was away from the helm, which should have been apparent from his reported position on the port side of the wheelhouse. The City of Louisville was fitted with a pilothouse alerter system, which was designed to sound first in the wheelhouse and then in other vessel spaces to alert other crewmembers that the operator was not responding.
Investigators found, several weeks after the grounding, that the power supply was missing, but they could not determine when it had been disconnected. Investigators were also not able to determine the interval that the alarm was set for (how long the operator could not move the rudder levers before the first alarm would sound in the wheelhouse).
The secondary alarm did not sound in the relief captain’s stateroom or the crew lounge before the grounding. Therefore, given the pilot’s estimate that he was away from the helm for 5 minutes, the system either had a time interval to alarm set to greater than 5 minutes or was disabled or nonoperational.
Conclusions
Probable cause
The National Transportation Safety Board determines that the probable cause of the grounding of the City of Louisville was the pilot leaving the helm unattended while operating his tow on the Mississippi River.
Lessons learned
- Using Pilothouse Alerter Systems
A pilothouse alerter, when used as intended, is an effective tool that can help ensure a towing vessel operator remains awake and vigilant while on duty (and notify another crewmember if the pilothouse alarm is not acknowledged). Established procedures for the operation and use of the system should be outlined in the company safety management system and should include the time interval for reset of the alerter system, which should be set based on the vessel’s navigational risk and proximity to navigational hazards (including traffic), as well as measures to ensure the system cannot be unintentionally reset.
