"Since LAND 3 comes on at 1500 feet RA it seems to me that the isolation takes place at this time."
The "seems" part is the bit I was trying to avoid, Aviator ;-)
I was hoping for some eye witness accounts (preferably not in a simulator). This way I could write to Boeing and tell them that their manual needs correcting... or at least clarifying.
By the way, on our aircraft, with one autopilot engaged before Loc intercept and the APP button pushed, all three CMD buttons light up. I believe there are variations to this. Hopefully, my eyewitness would be flying the same type.
Rgds.
Q.