The U.S. M1 Abrams tank is the safest tank ever built. Dozens of safety features enable the crew to survive accidents and enemy action, including hits by all manner of anti-tank weapons. But even when it's just driving around, it's a dangerous beast. Every years, fires break out in about one percent of M1's each year. Although America currently has about 7,900 M1's, far fewer are in active service. The most common causes are those that have made tanks dangerous from the beginning; hydraulic systems, fuel leaks and electrical problems. The M1 has added to this list the NBC (nuclear, biological, chemical) protection system, which causes fires about as often as the other three older items. Because of all the safety features, these fires rarely cause injuries or death. Let this be a reminder. No matter how well designed your combat vehicles is, these complex machines are still dangerous.