WASHINGTON: The captain of an amphibious US tour boat that sank during a sudden storm, killing 17 people, briefed passengers on lifejackets when the water was still calm, investigators say.
The National Transportation Safety Board (NTSB) is probing the July 19 incident involving a "duck" boat, which went down on Table Rock Lake near Branson city, Missouri.
It said it had completed a preliminary review of a digital video recorder system recovered from the vessel, which carried 29 passengers and two crew.
A survivor, Tia Coleman, who lost nine family members in the disaster, had said the captain told his charges, when the boat was already in the water, that they "won't need" life jackets.
"When it was time to grab them, it was too late and I believe that a lot of people could have been spared," she told Fox59 TV.
According to the NTSB, which on Friday released a chronology derived from the recording, at about 6:50 pm (2350 GMT) the captain began a safety briefing before the boat entered the water.
"The briefing included the location of emergency exits as well as the location of the life jackets. The captain then demonstrated the use of a life jacket and pointed out the location of the life rings," NTSB said.
"The water appeared calm," when the boat entered the water at about 6:55 pm, it continued. That was about 25 minutes after a weather warning had been issued.
The NTSB said that at roughly 7:00 pm whitecaps rapidly appeared on the water and winds increased, prompting the boat driver -- its second crew member -- to lower clear plastic side curtains.
That crew member died during the sinking, the sheriff's office has said. The captain survived.
According to the NTSB's summary, a bilge alarm sounded at 7:04 pm, stopped, and then sounded again at 7:07 pm.
In the final minutes of the recording, "water occasionally splashes inside the vehicle's passenger compartment," the NTSB said.
It cautioned that "no conclusions regarding the cause of the accident should be made from this preliminary information," as investigators continue their work.
The hybrid "duck" boats, with wheels allowing them to drive on roads but which can also travel on water, are popular with tourists in many cities.
They have been involved in previous fatal accidents. In 2002 the NTSB recommended that amphibious vehicles provide "reserve buoyancy" such as through watertight compartmentalization, to keep them afloat in the event of flooding.
The advisory followed the 1999 sinking of Miss Majestic, a former US Army landing vehicle, with the loss of 13 lives in Hot Springs, Arkansas, because of "inadequate maintenance," the NTSB said.