Low-Level Wind Climatology Related to Potential Wind Compression

Unanticipated adverse path-based wind shear can significantly affect airspeed of two or more aircraft being sequenced through a specific volume of airspace, possibly resulting in dangerous loss of separation known as wind compression. This compression of aircraft can be especially problematic when occurring on descent and final approach into Terminal Radar Approach Control (TRACON) airspace where there can be little room to maneuver, where mitigation / correction opportunities are more limited, and where controller and pilot workload is already high. Air Traffic Management (ATM) decision-makers currently seek to mitigate wind compression impacts by evaluating wind observations and weather model forecasts, but these efforts lack critical and explicit awareness of key objectively-identified and operationally-relevant wind shear thresholds and typical altitudes and wind directions commonly associated with adverse wind shear.

This paper helps address these operational wind shear needs by describing the wind climatology, generated from airborne wind observations at extended Terminal Radar Approach Control (TRACON) altitudes (1-28 kft), at seven key airports that commonly experience wind compression constraints. This climatology provides a valuable baseline on the characteristics and variability of horizontal winds by altitude, season, and time of day at each airport, noting environments where these winds may favor potential wind compression. To explicitly characterize the vertical distribution of winds during potential wind compression periods and how they may vary relative to underlying climatology, a focused climatology specifically targeting periods during which compression-contributing adverse shear was present will also be described.