HR or not?

[BaBa Booey]

I called it a ground rule double. I didn't have a rule / case book handy when I got home, but I was pretty sure once it hit the fence it was no longer in flight.

The coach argued that it was the same as Jose Canseco knocking the ball over the fence, but that ball WAS still in flight as it hadn't hit anything before hitting Jose in the head.

Thanks for the responses!