Resumen
Since most NextGen Operational Improvements (OIs) have been implemented recently, there is no traditional safety statistics, such as the number of accidents and/or incidents available to perform their formal safety evaluations. In this paper we present a process of safety assessment using precursors that may lead to unsafe outcomes. We use the radar track data to estimate traffic separations before and after NextGen OI implementation at Memphis International Airport (MEM). The FAA implemented Phase 1of wake re-categorization (RECAT) separation standards at MEM in November 2012. We examine the counts of wake, proximity, and anomalous trajectory events for two 30-day samples of pre- and post-RECAT periods. While the paper focuses on the methodology and is not intended to provide a detailed safety evaluation of RECAT, the findings suggest that RECAT implementation did not adversely affect the air traffic safety.