The Asiana Airlines captain who crashed a Boeing 777 at the San Francisco airport in July told investigators he was stressed out and "very concerned'' about attempting a visual approach landing.

Lee Kang Kuk says he was worried because the runway's automatic warning systems were out of service due to construction. An investigative report was released today at the start of a daylong NTSB hearing into the accident.

Also in the report: Federal investigators say a teenage girl who survived the crash only to be fatally struck by a fire truck actually was run over by two rescue vehicles in the accident's chaotic aftermath.

The documents released Wednesday indicated that the motionless girl was struck by two vehicles.

The head of the National Transportation Safety Board says there is an issue with automation in aviation that needs to be dealt with.

"We can always do better, and when we have accidents we have to learn from them, and that's what this event gives us the opportunity to do," said Deborah Hersman between sessions of a hearing looking into the July crash of an Asiana 777 at SFO.

Documents released at today's hearing show that the pilots were aware the plane was traveling too slowly and tried to correct it.  They also show the co-pilot thought the autothrottle on the jet might not have been operating.