Pilot fatigue from an untreated sleep disorder contributed to a January 2010 accident in Port Arthur, Texas, that dumped 462,000 gals. of oil into the Sabine-Neches Ship Channel, federal investigators concluded.

The 810’ tanker Eagle Otome collided with the 297’ barge Kirby 30406 being pushed by the towboat Dixie Vengeance. The Eagle Otome’s tanks were torn causing the state’s largest oil spill since 1990 when a Norwegian tanker spilled 5.1 million gals. while offloading crude southeast of Galveston.

The National Transportation Safety Board (NTSB) said one of the two pilots was tired because of sleep apnea and a schedule that didn’t provide enough rest. In addition, “contrary to pilot association guidelines, the first pilot on the Eagle Otome was conducting a radio call at a critical point in the waterway, and the radio call interfered with his ability to fully focus on conning the vessel,” the agency said in its report released this week.

The Sabine Pilots Association disagreed with the NTSB’s assertions.

“We have looked at the schedule of both of these pilots. The No. 1 pilot had well over 18 hours of rest prior to this assignment,” said Capt. Charles Tweedel, the presiding officer at the time of the incident. The second pilot had 14 hours rest. “I just can’t make the connection.”

Large ships are difficult to handle in the narrow waterway, “and the pilot did everything he could to try and regain control of the vessel,” said Tweedel, who attended the NTSB hearing in Washington, D.C.

Testimony also indicated that the second pilot was reading a newspaper during the transit.

“I don’t think that’s the professional behavior that we would expect of people. They’re not on there to read the paper,” said NTSB member Robert Sumwalt. “The pilots were not acting as a team.”

The pilots are there to spell each other, Capt. Tweedel said. They have an hour on navigation control and an hour off, “so you can be fresh when it’s your hour at the wheel.”

NTSB chairman Deborah Hersman focused on the agency’s conclusions, saying, “The NTSB has long been concerned about fatigue in the marine industry, and this accident highlights the very real consequences of degraded performance.”

The NTSB issued new safety recommendations to the Coast Guard, the pilots association and the Jefferson and Orange County Board of Pilot Commissioners. It also suggested that state governors require local pilot oversight organizations to implement fatigue mitigation and prevention programs.

Weather, mechanical failure, and drug or alcohol use were not factors in the accident that closed the waterway for five days, the NTSB said. No one was injured.