The pilot who was navigating an 810-foot tanker through the Sabine-Neches Ship Channel in 2010 was tired and suffering from a sleep disorder, while the second pilot was reading a newspaper, according to a National Transportation Safety Board report.

Federal investigators said Tuesday that these factors, in conjunction with lax regulations, contributed to the state’s biggest oil spill in 20 years.

The Eagle Otome tanker struck a towboat, dumping 462,000 gallons of oil into the waterway on Jan. 23, 2010. There were no deaths in the incident, but the collision shut down the busy 64-mile waterway for five days. The NTSB adopted the report on the incident at a Tuesday meeting in Washington.

Capt. Charles Tweedel of the Sabine Pilots Association, which is responsible for the safe movement of ships along the channel, disputed the NTSB’s report, saying the second pilot did assist in attempts to navigate and correct course during the incident. He also said that both pilots had adequate rest periods before beginning the assignment.

The NTSB report said the tanker’s pilots were not following the communications guidelines of the Sabine Pilots Association, violating rules that said one pilot should be navigating while the other handles radio communications. The NTSB ruled that weather was not a factor, nor was drugs or alcohol.

The maritime law lawyers at Schechter, Shaffer & Harris, L.L.P., Accident & Injury Lawyers represent offshore oil workers injured in accidents, and families of offshore workers killed in accidents.