Tell that to the American 757 Crew a couple of years back who correctly followed the QRH during an electrical malfunction and placed the 'Standby Power' switch ON but didn't have the systems knowledge to realize that that meant the battery was running the show. The Battery (which I think was advertised as good for 45 minutes) lasted an amazing 1:40.....and then systems started rapidly dropping off line. The plane diverted to KORD and went off the side of the runway.

I'm not saying we need to know how to build the airplane, but the level of systems knowledge we now get is pathetic. It's going to bite us in the butt one day.