Not sure if it qualifies as sexual abuse, but one of the first times I flew down here (being 23 or 24), I was seated next to a man who was about 50. I was by the window and he had the aisle seat. After a brief chat, found out he was coming down for business.
He fell asleep pretty quickly, and as I was settling in, he laid his arm across my lap. Thinking he had just passed out and maybe wasn't use to tight quarters, I pushed his arm off. Until he did it a second time... and I became suspicious he wasn't really sleeping. I shoved his arm off, wedged the pillow between our seats so he couldn't slide it over, and then couldn't sleep the rest of the flight for fear he might try sonething else. I thought about asking a flight attendant to be moved, but the plane was pretty packed, and I didn't want to cause trouble or a scene.
Maybe he was just unaware, but I doubt it. Pretty uncomfortable.
Guy was American, for what it's worth.