SANTA BARBARA, Calif. -- The Conception dive boat, which sunk on Labor Day killing 34 people off the coast of California, did not have a crewmember on roving overnight watch as required by its certificate, according to the National Transportation Safety Board.
"A crewmember sleeping in the wheelhouse berths was awakened by a noise and got up to investigate," the report says. "He saw a fire at the aft end of the sun deck, rising up from the salon compartment below. The crewmember alerted the crew behind the wheelhouse. As crewmembers awoke, the captain radioed a distress message to the Coast Guard."
Sumwalt told CNN in an interview that the incident is a "horrible, horrible tragedy" and the worst US transportation accident in some time.
The report came as experts are giving alarming safety assessments of small passenger and recreational vessels like Conception.
The preliminary report made no recommendations for safety improvements. The NTSB typically waits until its investigation is completed to make recommendations.
Truth Aquatics, owner of the Conception, did not respond to CNN's requests for comment.