With regulations for flying drones over the United States slowly but surely coming, theres serious scrutiny on their safety. Meanwhile, a new Washington Post report may cast some doubt on military models reliability: documents obtained by the paper detail how more than 400 large drones have crashed since 2001 — from communications failures, from mechanical errors and pilot mishaps, and occasionally sent straight into mountains to avoid catastrophe. Although none of the crashes caused deaths, the report isnt rosy for the future of unmanned flight. …