This document analyzes Army aviation mishap data from fiscal years 2008-2012 in Operation Enduring Freedom to determine periods of highest risk during deployments. It finds that while the conventional wisdom is that the first and last 60-90 days of deployments pose greatest risk, the data shows that mishap rates actually decrease over time as units gain experience. However, the significant drop in minor "Class E" mishaps late in deployments suggests under-reporting due to complacency. More study is needed to understand how seasonal factors and time deployed interact to impact risk. The key findings are that unit proficiency gained over time reduces risk more than other factors, and vigilance against complacency is important throughout deployments.