If it is exactly as you describe (I mean he is OK in the flight and only gets sick at the end, and always gets sick at roughly the same point), then I agree that this sounds more psychological than anything else.
But "psychological" doesn't mean "not real" - the evidence is in the bag so to speak! Probably he got sick on the first flight and this has become an unconscious habit.
You need to be utterly convincing and tell him you know how to help him get over it. Dont say anything else about it having become a habit. Try flying circuits a few times so he experiences the base/final turn without having time to get queasy. Then go off and fly the approach and landing pattern as an upper air exercise with him handling the controls, hopefully again he should be able to do this without being queasy. Then come back for a few more circuits without landing, then go for a landing without telling him which one you are going to land from.
The aim is to break the association in his mind that seems to be there between the final stages of the circuit and feeling sick.
I've no idea if this will work, but I reckon its worth a shot. Its what I would try in your situation.
Its worth not making a big deal about airsickness - lots of good aircrew can suffer from it.
hope this helps
H
Last edited by Heston; 15th Aug 2012 at 16:30.