On the morning of July 6, 2013 a Boeing 777-200ER from Asiana Airlines is on approach to runway 28L in San Francisco. Everything seems fine in the cockpit as the aircraft descends down. It soon becomes apparent that flight 241 is too low on the glideslope but by the time the flight crew notices this, it's too late. Why did The pilots continue? Why was this not noticed sooner and why did the autothrottle system not activate?