With regulations for flying drones over the United States slowly but surely coming, there's 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 isn't rosy for the future of unmanned flight. First, each crash can cost millions of dollars. Second, the crashes happened as frequently as fighter jet and attack plane crashes, despite representing a much smaller percentage of missions and flight hours. The Post's report, available here, also features a video of a Predator drone coming down.