I got a buddy into brewing and he immediately tried a high gravity beer as his second batch. (I think OG was around 1.08 or something.) Skip to a few months later and he is pretty disappointed because the batch has a strong fusel taste. (The beer has a strong estery taste with a pretty intense fusel finish. It is solventy, coats the throat, and won't go away.) I went back over his process with him and think I've found the culprit. Wanted to get a second (or third or fourth) opinion, though.
Basically, I think he pitched way too hot. He was using a Belgian strain (he forgets which one, but remembers it mentioned "Abbey" in the title; my guess is WLP530) and is confident that it was rated for the high 70s. He pitched two smack packs at the time, but remembers the kettle still being slightly warm when he pitched. (My guess is the wort was in the 90s.) His actual fermentation was in the high 60s to mid 70s, and he racked to a secondary (which I lent him) after three weeks. About five weeks in secondary at ambient temperatures (~72) and then into the bottles.
My thought is the fusels developed in those first few hours when the wort was too hot. I don't think he under-aerated because he poured the "cooled" wort into the fermenter through a strainer. I also think he had enough yeast since he used two smack packs (although I told him a starter next time would be a good idea). Anyone think there is something else I might be missing here? It seems the two most common fusel creators--under aeration and insufficient yeast--can be ruled out.