Quantifying the impact of severe weather on NAS performance

Measuring air traffic system performance is difficult due to the dramatic effects of uncontrollable variables, especially weather. An effective performance metric should somehow account for the influence of weather, either to normalize the metric to some base scenario (e.g. a clear weather condition), or to measure the effectiveness of traffic flow management (TFM) strategies relative to historical performance in “similar” weather conditions. Both of these require quantifying the weather influence, which depends primarily on the severity of the weather combined with its correlation to air traffic flows in space and time. We investigate methods for calculating a “weather index” value by correlating convective weather with air traffic data, and demonstrate its practical use for performance measurement.