flying mom,
if euthanasia isn't option for you, there are couple of points to consider...
your son is 15, by the time he hits 18 and experienced the delights of the opposite sex*, cars, etc the game plan could well have changed. there is hope for you !
however, in the event that his head is not turned by the fairer sex, job prospects that offer financial reward, stability and security you will have your work cut out, so will he.
at the age he is there is still opportunity to gain advantage, physics and mathematics will be of key importance right now as the career does use these subjects considerably (unfortunately second guessing JAA/EASA/ What it will be in future is not an academic subject).
has he looked at the air cadets ? at his age that may be a good start.
also, in all honesty any medical conditions that could preclude a class 1 medical ? eyesight problems, balance problems, any family history of psychosis etc etc.
before you go even thinking about blowing a large amount of money on pursuing a career for him you want to be sure he is going to be able to get a medical and have the academic base to deal with the subject matter and study.
don't push him away from it as DU suggested but be supportive as well as honestly practical about the reality. there are many people that have dropped away from completing their professional licenses, through medical or personal problems, many who have attained them but not found the openings to allow them to pursue the application of their license and many that have gone on to enjoy a good career in the industry.
* in order to be PC compliant the reader is free to substitute 'female', with 'male' or 'trans-gender' or 'Cherie Blair' as applicable.