Low-level windshear alert system
A low-level windshear alert system (LLWAS) measures average surface wind speed and direction using a network of remote sensor stations, situated near runways and along approach or departure corridors at an airport.Arriving aircraft on descent, generally within six nautical miles of touchdown will fly within this low level, maintaining a glide slope and may lack recovery altitude sufficient to avoid a stall or flight-into-terrain if caught unaware by a microburst.Air traffic controller (ATC) users at local, ground and departure positions in the ATCT relay the LLWAS runway specific alerts to pilots via voice radio communication.The LLWAS-RS program began in response to the National Transportation Safety Board (NTSB) investigation of the USAir Flight 1016 accident at Charlotte, North Carolina, in 1994.From that accident, a determination was made that LLWAS-II must regain and retain its original capability, often degraded by tree growth and airport construction such as hangars that obstruct or deflect wind near LLWAS remote station sensors.
wind speeddirectionremote sensorWind sheargust frontsmicroburstsvertical shearderechosanemometerAir Traffic Control ToweralgorithmsAir traffic controllerprecipitationFederal Aviation AdministrationEastern Air Lines Flight 66Project NIMRODTed Fujitaweather radarTerminal Doppler Weather RadarNational Transportation Safety BoardUSAir Flight 1016Index of aviation articlesAirborne wind shear detection and alert systemCenter Weather Service UnitNEXRADmeteorological equipment and instrumentationAtmometerBarographBarometerCeiling balloonCeiling projectorCeilometerDark adaptor gogglesDewcellDisdrometerDropsondeField millHeat flux sensorHygrometerIce accretion indicatorLightning detectorNephelometerNephoscopePan evaporationPyranometerPyrheliometerPresent weather sensorRadiosondeRain gaugeSnow gaugeSnowboardSnow pillowSolarimeterSounding rocketStevenson screenSunshine recorderTethersondeThermo-hygrographThermometerTide gaugeTransmissometerWeather balloonWeather buoyWeather vaneWhole sky cameraWind profilerWindsockweather stationsAircraft report (AIREP)Automated airport weather stationAutomatic weather station (AWS)Binary Universal Form for the Representation of meteorological data (BUFR)Hurricane HuntersMesonetMeteorological Aerodrome Report (METAR)Pilot report (PIREP)Weather shipAircraft Communication Addressing and Reporting System (ACARS)Aircraft Meteorological Data Relay (AMDAR)Automated Meteorological Data Acquisition System (AMeDAS)Deep-ocean Assessment and Reporting of Tsunamis (DART)FluxNet Project (FluxNet)Global Atmosphere Watch (GAW)Global Sea Level Observing System (GLOSS)Prediction and Research Moored Array in the Atlantic (PIRATA)Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA)Tropical Atmosphere Ocean project (TAO/TRITON)Voluntary observing ship programCitizen Weather Observer Program (CWOP)Coastal-Marine Automated Network (C-MAN)NEXRAD radarSnow Telemetry (SNOTEL)Remote Automated Weather Station (RAWS)Road Weather Information System (RWIS)Tropospheric Airborne Meteorological Data Reporting (TAMDAR)