Investigators believe the ferry Sewol capsized when an inexperienced third mate steering it suddenly performed a sharp turn.
Park Han-gyeol (26) had worked aboard the ferry for only around four months and this was the first time she navigated the ship through the treacherous coastal waterway from Incheon to Jeju Island, investigators said.
Originally, the first mate was supposed to navigate the Sewol, but the ferry left Incheon two hours later than scheduled due to heavy fog and he handed over to Park at the end of his shift.
Normally, three teams of navigator and helmsman work four-hour shifts aboard the ferries. The team with the third mate at the helm took over at 8 a.m. as scheduled. If the Sewol had departed on schedule at 7 p.m. on April 15, it would have passed through the coastal waterway two hours earlier with the first mate at the helm.
There are no regulations preventing third mates from navigating vessels in difficult waters, prosecutors said. But the captain must direct a vessel when it is passing through a narrow passage or in potentially threatening situations. The Sewol's captain was not on the bridge but in his quarters when the ship capsized.
"The ship's captain does not have to work shifts so his timeframe of responsibility is broader," an investigator said.
Park told prosecutors that she changed the ship's direction at normal speed but is refusing to say why. The helmsman who was steering the ferry on Park's watch claims he merely obeyed her instructions.