Spiegel's Nicola Abé wrote a very interesting story on The Woes of an American Drone Operator. It includes the conversation between two drone pilots, right after firing a Hellfire missile only to see a kid appear on their targeting screens a second before impact:

"Did we just kill a kid?" he asked the man sitting next to him.

"Yeah, I guess that was a kid," the pilot replied.

"Was that a kid?" they wrote into a chat window on the monitor.

Then, someone they didn't know answered, someone sitting in a military command center somewhere in the world who had observed their attack. "No. That was a dog," the person wrote.

They reviewed the scene on video. A dog on two legs?

Terrifying. No wonder our drone pilots are burning out. [Spiegel]