My personal experience: I failed the AFF level 3 (release) jump twice, after passing levels 1 and 2. After the second time I failed level 3, I drove to the wind tunnel in Vegas and spent an hour in there. When I came back, I passed 3,4,5,6,7 all in two days without failing any of them. I think even 30 minutes in the tunnel can significantly improve an AFF student's flying skills.
Now if we just had a canopy tunnel ...
Edit to add this:
Does relaxation ability in the tunnel lead to the same in the sky?
Also in my experience, no. Tunnels and jumping are still different enough for me that after spending an hour in the tunnel, I experienced no difference in my arousal level when making the next AFF jump. For me, the only thing that made me relax was getting more skydives. Maybe others have a different experience.
(This post was edited by riddler on Aug 3, 2006, 8:05 AM)