Wind-Shear System Cost-Benefit Analysis

A series of fatal commercial aviation accidents starting in the 1970s led to the identification of thunderstorm-related wind shear as a critical hazard to aircraft takeoffs and landings. In aggregate, these accidents resulted in over 400 fatalities and pressured the Federal Aviation Administration (FAA) to develop effective warning technologies. In response, the aviation community invested in and deployed wind-shear protection systems, ranging from pilot training for avoidance and recovery to sophisticated Doppler-radar detection algorithms for wind-shear warnings and detections. This intense research effort led directly to the creation of Lincoln Laboratory's Weather Sensing Group, and the aggressive development and implementation program that followed resulted in the operational deployment of the Terminal Doppler Weather Radar (TDWR) at 46 airports during the 1990s and a Weather Systems Processor (WSP) modification for 35 existing Airport Surveillance Radars (ASR-9). In parallel, other organizations made improvements to the existing Low-Level Wind-Shear Alert System (LLWAS) for smaller airports. To date, there has not been a wind-shear-related accident at an airport that operates one of these modern wind-shear detection systems. The safety improvement was driven not only by the deployment of ground-based systems but also by improved pilot awareness and airborne onboard forward-looking radars (Predictive Wind-Shear System, or PWS). In addition, deployment of ground-based systems with automated alerts and associated training have enhanced air traffic controllers' awareness of wind shear and greatly improved their ability to provide pilots with proactive advisories of hazardous conditions. Mitigating thunderstorm wind-shear threats for aircraft near the ground has been an important issue since the 1970s, when several fatal commercial aviation accidents were attributed to wind shear. Updating the knowledge base for airport wind-shear exposure and effectiveness of detection systems has become critical to the Federal Aviation Administration as they consider options for aging systems and evaluations of new systems.