Fatigue the Key Cause of Tugboat Collision with USCG Cutter


A frame from video captured by the Tampa’s stern camera at the time of contact. A yellow arrow highlights the Cerro Santiago, which was traveling stern first. In the foreground is the temporary shelter on the helicopter deck for the cutter’s detainees. (Photo courtesy of Coast Guard)

In April 2017, while transiting northbound through the Panama Canal, the Panama-flagged tugboat ‘Cerro Santiago’ collided with the USCG cutter ‘Tampa’ in Miraflores Lake, Panama. Although the tugboat was not damaged, the cutter sustained $170,018 in damage to the stern, as well as to various systems in the steering gear room. The NTSB issued an investigation report on the incident.

The incident:

About 0020, the Tampa was following a northbound vessel, the Bahamas-flagged containership Atlantic Acanthus, toward the west lane of the locks. The Atlantic Acanthus was proceeding on a course over ground of 314 degrees at a speed of 1.4 knots.

Around this time, the pilot and navigation team on the Tampa identified a southbound tugboat—later determined to be the Cerro Santiago, which had passed down the starboard side of the northbound Atlantic Acanthus—approaching on a course where it would also pass down the starboard side of the cutter. At 0023, the Cerro Santiago navigated to a position ahead of the Sun Ploeg to clear the approach for the Atlantic Acanthus.

According to the members of the Tampa’s navigation team, the tugboat’s deck lights were so intense that the lighting impacted their night vision. After the tugboat passed safely down the starboard side of the Tampa, the pilot and navigation team aboard the cutter focused their attention on the approach to the locks and the vessel traffic ahead. However, the Cerro Santiago suddenly rotated to starboard from its southerly course and, while still traveling stern first, began heading toward the Tampa. At 0029, the tugboat collided with the stern of the cutter to starboard.

Damaged stern of the Tampa, which was moored postaccident in the anchorage off Colón on the Atlantic Ocean side of the canal.

Although investigators were not allowed to interview the master of the Cerro Santiago to explore the results of his most recent merchant mariner physical examination or his medical conditions, they determined that fatigue was a factor in this accident, based on his work/rest cycle preceding the accident, on the increased workload placed on him, and on the time at which the accident occurred.

As explained, the collision between the Tampa and the Cerro Santiago occurred at 0029, not too long after midnight, at a time of morning when individuals are biologically predisposed to sleep. The master had been working in the wheelhouse alone for a period of time that exceeded 8 continuous hours. It was his seventh consecutive day of similar shift work followed by the overtime he was working while awaiting his relief; consequently, as he acknowledged, he was “tired.”

On the early morning of the accident at 0029 on April 18, the master had just completed his seventh consecutive 8-hour shift and, though scheduled to be off duty, was working overtime until his relief arrived.

NTSB notes that long work hours and extended shifts lead not only to fatigue, but also to physical and mental stress. Furthermore, working schedules that alternate daytime work with nighttime work in the same week can diminish performance and result in sleep deprivation. In these situations, a worker is not able to get sleep of sufficient duration because of the insufficient time between work shifts, along with the logistics associated with commuting to and from the worksite and the often-competing demands for his/her time for family and personal life.

Probable Cause:

NTSB determines that the probable cause of the collision between the tugboat Cerro Santiago and the US Coast Guard cutter Tampa was the failure of the master of the Cerro Santiago to maintain a vigilant watch due to fatigue.

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Source: NTSB


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