The cockpit voice recorder of Asiana Airlines Flight 214 appears to show the pilots attempting to abort the landing just 1.5 seconds before it crashed at San Francisco International Airport, the National Transportation Safety Board chairman said Sunday.

The pilots appear to have increased speed 7 seconds before impact, and they then "called to initiate a go-around 1.5 seconds to impact," Deborah Hersman said.

The NTSB's preliminary assessment of the plane's cockpit and flight data recorders show the flight was coming in too slow and too low, but Hersman stopped short of pinning the blame on the pilots.