Airborne school slots aren't too common to get for 11Bs throughout the 101st (division pathfinders lost their active jump status like a year ago, and they were the last Airborne unit). All 11As I've met went through during West Point or ROTC before Ranger School, but only some of the more senior enlisted (or dudes who PCS from Airborne units) rock the winged 'chute around here.
Air Assault School on the other hand, is extremely common. Something like 90% or more of a line Infantry company is Air Assault qualified (and yet division as a whole is only at like 40%, thanks POGs), new guys are sent within a couple weeks of reporting, and get (hazed, then) sent back if they don't pass. I don't know how you guys are going to recreate the silliness of AASLT in Arma, but if I weren't out of the country right now I'd dig up the old Sabalauski Air Assault School handbook for you. There's probably a digital version floating around the internet anyway.