The captain of Asiana Flight 214 blamed no runway lights at San Francisco International Airport for a “very stressful” approach that became a crash, according to a federal reported released on Wednesday. Pilot Lee Kang Kuk also told the National Transportation Safety Board that he mistakenly thought the automatic throttle was engaged when it was not, which led to the plane being 34 knots under its required landing velocity when it crashed. While the report sheds light on the pilot’s frame of mind, the NTSB has not made formal conclusions about the cause of the crash. Boeing representatives said safety is ultimately the responsibility of pilots, not automated flight systems. The crash left three dead and more than 180 injured.