With zero specific knowledge of the system(s) at Toronto, I suspect that @767-300ER has nailed it. 300-series airplanes (767 and especially 777) are extremely long frames. While your nose wheel may be ON the center line and in exactly the right place, I think it is possible that the gate approach curve is simply too short for the remainder of the aircraft to become straight-in and before you reach the absolute STOP line. Maybe?
I've heard other 773 drivers mention this about a few other airports, but not at Toronto.
I have no idea how many position sensors the most current automatic docking systems use, but I'm sure that they measure and consider a lot more than the position of your nose wheel.
Have you considered asking your OPS folks to inquire of the folks who operate those systems as Toronto? Sure, there is a tiny degree of tolerance for variations in 'red light generating' position signals, but the 777 drivers need to know what they are. In the case of a few taxiways, alleys and apron gates that are extremely tight, I think a few airports have provided a second,
clearly marked guide curve for for the super-longs. I can see the need when parking the A380 and the 747-8.
Does ANY airport currently use 'automagic' gate approach/parking systems for for the latter two?
This is way out of my league, but I'm curious... One heck of a great question!
