A Terminal Doppler Weather Radar (TDWR) system detects and reports hazardous weather in and around airport terminal approach and departure zones. The TDWR identifies and warns air traffic controllers (ATCs) of low altitude wind shear hazards caused by microbursts and gust fronts, in addition to reporting on precipitation intensities and providing advanced warning of wind shifts.
TDWR antennas are located near but not on a primary airport site. The radar is specially designed to operate in a high clutter environment normally present in the vicinity of airports. It makes use of a variety of methods to minimize clutter and to eliminate the influence of such moving targets as birds, aircraft and automobiles. In this way the TDWR can accurately measure the radial wind speed and its fluctuation from which low level windshear can be computed.
The ATCs use the TDWR reports to warn pilots who are potentially affected by the hazardous weather patterns.
TDWR was first used operationally in the USA in the 1990s where it has gradually replaced anememometer-based low-level wind shear alert systems in USA. TDWR is also being installed in other countries outside USA where wind shear and microbursts are a particular hazard.