because they had heard it intermittently before. they didn't know if it was valid or not and decided to disregard it but we'll never know. they never discussed it. >> the official french investigative report states that a phenomenon called the startle effect may have played a role. >> it's similar to walking into a room that's dark and somebody jumping out and saying boo, it's that instantaneous scare, if you will, okay, the auto pilot is off. why is it off? do i need to do and you have to process this information in a compressed timeline. >> human beings, when they are very, very, very focused on one task, things will drop out. oral inputs are one of the first to go. so this is consistent with this buy l pilot not hearing the stall warning. >> prior to the crash of 447, airbus and air france recognized