Departure flow efficiency and the identification of causes for inefficiencies

As a proposed indicator of operational efficiency in the National Airspace System (NAS), a new Departure Flow Efficiency (DFE) metric has been formulated. For a major metropolitan airport, the DFE considers flight times from departure to a 175 nautical mile (NM) radius from the airport, with population stratification by aircraft performance, departure runway, and azimuth of a flight's radius crossing (i.e., the measure of the angle, from zero to 360 degrees, formed from the Airport Reference Point¹ to the point of radius crossing). As more flights follow efficient lateral and vertical profiles, the average daily DFE metric value goes up. For a given day, a high DFE metric value implies that many flights were expedited, indicating efficient departure operations. An “exception report” is needed to identify operating conditions that may result in an inefficient departure when a low DFE metric value is computed. The intent is to test for a correlation with meteorological or other conditions. Three cases are examined: (1) flights exhibiting a nominal speed, but traversing an extended distance, (2) flights traversing a nominal distance, but exhibiting a slow speed, and (3) impeded short-hop flights. Case 1 may be caused by flight deviations around severe weather areas. Case 2 may be caused by a conventional climb profile against a strong headwind or an altitude profile with an extended period of low altitude flying to stay under severe weather. Case 3 may be caused by arrival constraints at the destination airport. Analysis to discern these three cases involves the use of flight track data, as well as Rapid Update Cycle (RUC) winds data and National Convective Weather Diagnostic (NCWD) data. In addition, an algorithm for the detection of holding patterns and delay vectors in archived operational data was employed for Case 3.