Bernd Wannenwetsch groped the dozing woman on a flight from Amsterdam to Aberdeen on November 11 last year.
The Aberdeen University professor thought the 26-year-old woman's closed eyes meant she was enjoying it - but she was actually trying to sleep.
He also asked the woman, who cannot be named, if she enjoyed being touched by him - despite the fact she woke up terrified as he grabbed her breast and thigh.
During the trial, Wannenwetsch, 53, admitted committing a "moral wrong" by touching the woman on the plane - but he denied sexually assaulting her. The ordained minister claimed it was a consensual act that he has regretted "every day".