Asiana Airlines crash pilots knew speed was low

An Asiana Airlines Boeing 777 plane is engulfed in smoke on the tarmac after a crash landing at San Francisco International Airport in California on July 6, 2013, in this handout file photo provided by passenger Eugene Anthony Rah, released to Reuter
An Asiana Airlines Boeing 777 plane is engulfed in smoke on the tarmac after a crash landing at San Francisco International Airport in California on July 6, 2013, in this handout file photo provided by passenger Eugene Anthony Rah, released to Reuters on July 8, 2013. Pilots of an Asiana Airlines plane that crash-landed in San Francisco in July were aware that the plane was travelling too slowly and tried to correct it in the final seconds before impact, documents released on Wednesday, Dec 11, 2013, by US aviation safety investigators show. -- FILE PHOTO: REUTERS

WASHINGTON (REUTERS, AP) - Pilots of an Asiana Airlines plane that crash-landed in San Francisco in July were aware that the plane was travelling too slowly and tried to correct it in the final seconds before impact, documents released on Wednesday by US aviation safety investigators show.

The crash on July 6 killed three people and injured more than 180, the first fatal commercial airplane crash in the US since February 2009.

The co-pilot of the jet, who was training the pilot flying the plane, thought the auto-throttle on the Boeing Co 777 plane might not have been operating, the documents show. The pilot who was flying the plane said he wasn't sure whether auto-throttle was maintaining speed, documents show.

Lee Kang Kuk, a 46-year-old pilot for the Korean airline who was landing the big jet for his first time at San Francisco, “stated it was very difficult to perform a visual approach with a heavy airplane,” according to an investigative report released Wednesday.

He told investigators he was stressed out and “very concerned” about attempting a visual approach because the runway’s automatic warning systems were out of service due to construction.

The low, slow landing caused the plane's tail to hit a seawall short of the runway. The plane spun 330 degrees as it broke apart and caught fire, strewing wreckage along the runway.

The National Transportation Safety Board released dozens of detailed documents related to the crash as it opened an investigative hearing into its causes.