I'm thinking, though, Great Britain? And Foster ends up a professional test pilot at 28.

I'd still go with Foster joining the RAF to become a pilot - at least then you don't have to worry about how he was earning his money to get flying lessons. 

Also - since I've been researching the RAF for Freeman's backstory - since Foster would have needed either a college degree or gone to the RAF College for 2 to 3 years to become an officer and pilot (unless I've read everything completely wrong) going RAF would make even more sense. He could go in at 17, maybe even younger, and get in his schooling. No problem getting his pilot's ticket at 20, then.

Of course there's the option that when Foster says he's been a pilot for 8 years - that time could be construed as overlapping his time as a test pilot. So his total time as a pilot is 8 years and he got his pilot's license at 22. He got his degree in whatever at University before going becoming a pilot. 

Congratulations 

I double checked - if Foster had gone through the RAF school for three years, he would have been signed on for an 18 year term. And in 1971 they went to college grads only for flight school and officer training. So Foster is a college grad and I think Matt has him as an aeronautical engineer, so that works nicely.

The USAF test pilot course takes 6 months (at least it used to and I doubt it's been changed). They don't teach flying, but how to understand what's going on with the plane in flight and how to write it down so the engineers understand it.

If Foster was an engineer before getting his pilot's ticket, then he might have been ahead of the game for becoming a test pilot. I don't know if the big aerospace companies have test pilot schools or if there's a commercial one - there probably is.

It's nice to have confirmation on these things. The next nit-picky point is apparently the RAF requires a 12 year commitment for their pilots and air officers but it looks like Foster was released after 6 years (not long after his second UFO sighting) - and with test pilot training to boot.

Good thing this is fiction. 

My biggest concern is that if the RAF simply flushed him for something like 'mental instability' for seeing flying saucers, that would negatively affect his beginning career as a test pilot. Unless there was another excuse they could use to save face - their own as well as Foster's.

Kofax didn't seen to be aware of any prior issues with Foster and I figure he would know people who would tell him if there were.

Maybe Foster had earlier tested a VAC plane for the RAF and Kovacs openly wanted to hire him. That would give the RAF an excuse to 'down-size' Foster out of the service without admitting that they let someone who sees UFOs into test pilot training. And maybe, just maybe, the person who got Foster's sighting reports 'suggested' to the RAF that they not put anything into Foster's record that might come back on them later and/or they cut a deal with Foster that he could keep his flight rating so long as he kept his mouth shut about seeing things.

Just some thoughts. 

Okay, with that scenario, if Foster had been given 'non-active' status with the RAF (not sure exactly how that would work but it sounds good) to work with VAC, then his actual departure from the RAF would have been after the crash of the XV-104 and most likely when he joined SHADO.

Now leaving the RAF (or even VAC) for a film company might raise questions, but those could be explained away by claiming he had physical injuries from the crash that kept him from continuing as test pilot and there were still questions concerning the crash itself.