Verticality, unless both pilot and co-pilot are GIANTS and the real-world ones were dwarves. Look at the eyeline of each. And look at the shoulder width of the mimics? They don't look even vaguely real, unless modern pilots are all 6` 6", and I KNOW they aren't - I'm 5` 8 and still taller than many of my mates in the flying club, although many of the veterans have shrunk because of all the `g` they've pulled!