BEagle
>We never found the need to use any sort of screen in the RAF - occasionally the odd student had to be made to wear a visor if he tried to cheat<
I confess I haven't had your military experience; but I know a man who has. He tells me that:
a) Screens are used in some military types (eg he used them on the Harrier)
b) Visors are used by all ab-initio students in their training (eg on Jet Provosts and Tucanos)
That said, you might have a point about them there screens!
