On April 14, 1994, two U. S. Air Force F-15 fighters accidentally shot down two U. S. Army Black Hawk Helicopters over Northern Iraq, killing all twenty-six peacekeepers onboard. In response to this disaster the complete array of military and civilian investigative and judicial procedures ran their course. After almost two years of investigation with virtually unlimited resources, no culprit emerged, no bad guy showed himself, no smoking gun was found. This book attempts to make sense of this tragedy - a tragedy that on its surface makes no sense at all. With almost twenty years in uniform and a Ph. D. in organizational behavior, Lieutenant Colonel Snook writes from a unique perspective. A victim of friendly fire himself, he develops individual, group, organizational, and cross-level accounts of the accident and applies a rigorous analysis based on behavioral science theory to account for critical links in the causal chain of events. By explaining separate pieces of the puzzle, and analyzing each at a different level, the author removes much of the mystery surrounding the shootdown. Based on a grounded theory analysis, Snook offers a dynamic, cross-level mechanism he calls 'practical drift' - the slow, steady uncoupling of practice from written procedure - to complete his explanation. His conclusion is disturbing. This accident happened because, or perhaps in spite of everyone behaving just the way we would expect them to behave, just the way theory would predict. The shootdown was a normal accident in a highly reliable organization.