His reasoning was that most people's eyes move left to right when examining something - which mimics their eye movement when reading text (at least in Western societies. In R-L countries I guess the opposite would be true).
He said that by position the nose/cockpit of the aircraft on the left side, people's eyes would always go to where the 'little humans' would sit first, then move away towards the right. Similarly if you had scale model humans in a diorama setting - place them on the left hand side.
Placing the vehicles going against their eye movement would also make their attention 'catch' and stop at details of the object 'moving' in the opposite way (something about how people who drive cars are just more instinctually aware of something that is moving against their direction of travel). Whereas if they had to scan in the same direction the vehicle was moving, their attention would just slip past interesting points.
I've used those lessons in most of my UX design nowadays. Placing buttons and important items towards the right of a page, with lesser items further right. The only exception is if it is a destructive action call (deleting a record etc.), then I usually place the button all the way to the right so it isn't in visual way and too tempting.