Prior to the other day I probably would have said to go ahead and start
him. I was at a safety semenar the other day and several people had had
their teenagers start flying at your son's age. Both their sons ended
up not becoming pilots (one had been a CAP cadet and involved in
aviation his whole life).
As the father of two pre-teen boys and a BSA leader I understand that
it takes boys a lot of energy to ramp up to a large challenge like
learning to fly. One thing I've found for sure is that boys don't like
to ramp up twice. Another thing is that kids today are very, very busy
with school, outside activities, sports, etc. While most of us were
just working 9-5 while we learned to fly most kids today are busy from
6am-9pm with activities.
So, all that said, the experience of those at this semenar was that
their boys ramped up and achieved their solo, then got busy with other
stuff (since they had a year to get their private) and then had an
impossible time re-engaging when it was time to take a checkride.
Both my boys will be in your son's situation in a few years and I'll
wait until they're old enough to go right through and get their
private.

-Robert, CFI

Jay Honeck wrote:
My son is 15. He'll be turning 16 in August, and starting his Junior year
of high school.

He's been flying since he can remember, and has many hours in the right
seat. (He's got over 1500 hours as a passenger with Mary and me.) His first
dozen or so hours behind the yoke were "IFR" -- because he couldn't see over
the panel! He can do everything except land the plane -- and I'm fairly
certain he could do that, but I'm not about to risk our lives (or my plane)
to find out.
"