As the flight bound from Incheon in South Korea approached San Francisco after its 11-hour journey across the Pacific Ocean, three out of four pilots aboard were in the cockpit.
Lee Kang-kuk, who was still completing his initial training on the Boeing 777 and had never before flown one into San Francisco, was at the controls, Ms Hersman said on Tuesday.
Beside him and in command of the aeroplane was an instructor pilot, flying in that capacity for the first time, Ms Hersman said.
In the jump seat behind the two pilots was a relief first officer who had flown to San Francisco five or six times as a monitoring pilot. A fourth crewman, serving as relief captain, was in the cabin as the plane landed, and was still being interviewed by investigators on Tuesday.
As the plane approached on a clear day, the pilot in control of the plane was cleared to land. About 34 seconds prior to impact, the plane was flying at 500ft and at about 134 knots (154mph; 248km/h), when the instructor pilot realised it was flying too low.
He told the pilot to pull back on the stick, and seconds later he realised that the automated throttle controls, which had been engaged, were not maintaining the correct speed of 137 knots. About eight seconds before impact, the pilot in control pushed the throttles forward to speed up.
Less than two seconds before the crash, the pilot tried to abort the landing, but it was too late. The plane came in much too shallow. The main landing gear struck a sea wall well short of the end of the runway, then the tail struck and was ripped off the rear of the aircraft.
The aeroplane then rotated left and went into 360-degree spin before coming to rest to the left of the runway.
The first officer was hospitalised with a cracked rib, and neither of the two pilots were seriously injured.
