I did the pilapt tests, and improved my aptitude considerably by sleeping off the booze!
I suppose if you can improve aptitude via the medium of practice, then the question remains; How do you genuinely demonstrate ability (or lack thereof) in any given field? I imagine it must be a helluva feeling waking up one day, after spending many £000's, to realise that you just can't handle the job...
JR
p.s. My Pilapt scores were "good" "good" "sexy" "moist" and "chocolate sauce"
p.p.s. (
sorry 
)