Tying Fatigue Troughs to Collision and Grounding Precursors

The third mate on the Exxon Valdez had slept five to six hours in the 24 before grounding on Bligh Reef. The Cosco Busan pilot's cognitive state was compromised when the ship allided with the Bay Bridge. The fatigue troughs were already in the record. The precursor correlations were not.

In the NTSB Marine Accident Report on the Exxon Valdez, the third mate's sleep in the 24 hours before the grounding is documented at five to six hours. The NTSB lists fatigue among the probable causes. A generation later, the NTSB report on the Cosco Busan allision with the San Francisco Bay Bridge cites degraded pilot cognitive performance — medication effects combined with bridge communication failures — as a cause of the 53,500-gallon spill. A VLCC and a Panamax container vessel, two decades apart, same cognitive signature in the casualty file.