The National Transportation Safety Board (NTSB) has found that a crucial mistake by a harbor pilot caused a tanker to hit a refinery pier during a routine undocking in California.

This incident took place on October 14, 2024, when the 820-foot crude oil tanker Platanos was leaving the Martinez Refining Company Wharf in the Carquinez Strait. At around 4:12 AM local time, the ship's side hit a concrete fender structure, resulting in over $500,000 in damages. Fortunately, there were no injuries or pollution.

The NTSB reported that the accident happened because the pilot mixed up the positions of two assist tugs on his reference card and mistakenly gave commands for one tug to the other.

The undocking maneuver was standard. Two tractor tugs were stationed on the tanker’s starboard side—one at the front and one at the back—to help pull the vessel away from the dock against a current of about 1.9 knots. The pilot's plan was to pull the back of the ship away faster than the front to counteract the current and safely clear the pier.

However, the swapped tug commands resulted in the opposite effect.

According to investigators, “the bow [was] rapidly pulled away from the pier, causing the stern of the ship to move toward the pier,” which ultimately led to the collision.

Data from the voyage recorder shows things got worse quickly. Just seconds after the pilot directed an increased pull from what he thought was the back tug, the vessel’s stern closed in and hit the pier.

The ship's captain noticed the potential danger and warned the pilot that the stern was “too close” about 30 seconds before the impact. However, by that time, it was too late to fix the maneuver. Investigators concluded that there were no practical steps the bridge crew could take to avoid the collision, especially given the confusion about the tug positions and the limited visibility in the dark.

The NTSB found no mechanical issues with either the vessel or the tugs, and the weather was good. The investigation instead highlighted human factors, describing the error as a typical “slip or lapse” during a routine task.

The pilot, who had over 30 years of experience and knew the berth well, had incorrectly written down the tug positions on a handheld “radio card” meant for quick reference during maneuvers. This mistake led to a flawed understanding of how the ship would react to tug commands.

Investigators pointed out that the pilot had only around 4.5 hours of sleep before the early-morning operation, and the incident happened during a time of low alertness between 3 AM and 5 AM. Although fatigue might have played a role in the loss of attention, it was not ruled as the direct cause.

The damage to the Platanos included a hull breach above the waterline into a pump room, as well as buckling and cracking along the port side. The pier suffered from concrete damage and structural cracking to the fender system.

After the incident, the vessel was able to proceed to a safe anchorage.

The NTSB concluded that the likely cause was the pilot’s mix-up of tug positions and the resulting incorrect commands during the undocking process.

For more details, the full report can be accessed on the NTSB website.