didnt they featcher that on Air Crash Invesigators?

Probably, wake vorticies have caused several accidents including some big ones.

I did always think it was the aircrafts size that made the wake less effective, such as a 747 beacuse of its larger wing span to a DC-9 its wake was bigger

It's not actually so much wingspan as it is weight and speed and configuration. The worst comes from planes that are heavy "clean" and slow. It's a sort of a function of how much lift is being generated and spilled over the wingtip. So yes the bigger planes make worse ones but it's more to do with weight and lift than the specific wingspan. Wingtip vorticies from big planes also do annoying things like sink and get pushed around by the wind so you have to be careful when you're near a big plane.

*Nods* Nothin' sets the mood like a pile of smokin' wreckage and corpses.

someones been playing AC again

Actually, no. Played Terminator: Dawn Of Fate, and today, Terminator: Rise Of The Machines. I will be playing 04-0-5 after that though.

These are airplanes, after all, so I guess the amount of fucking around they want to discourage is pretty high. :P

So fuck waiting for those "scared straight" videos later on in the classes, they're gonna get started on scaring the stupid out of you right away in the manuals. xD