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WAAS Ground Segment

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Title WAAS Ground Segment
Edited by GMV
Level Basic
Year of Publication 2011
Logo GMV.png

The Wide Area Augmentation System (WAAS) is the United States Satellite Based Augmentation System. The programme, started in 1992, is being carried out by the Federal Aviation Agency (FAA)[1] and is specially developed for the civil aviation community.[2] The system, which was declared operational on July 10, 2003,[3] currently supports thousands of aircraft instrument approaches in more than one thousand airports in USA and Canada.[4] WAAS service area includes CONUS, Alaska, Canada and Mexico.[5] The WAAS programme is continuously in evolution; three development phases have been already covered, and there are on-going plans to improve the capability of the system in parallel with the evolution of the SBAS standards towards a dual-frequency augmentation service.[6]

WAAS Ground Segment

WAAS works by processing GPS data collected by a network of reference stations to generate the SBAS message which is uploaded to the GEO satellites. The GEO satellites broadcast this information to the user receivers, which compute the aircraft positioning and inform on potential alert messages.[7]

WAAS System

The WAAS system components are typically divided in three different segments: the ground segment, encompassing the system assets located on ground, the space segment, including the GEO satellites used to broadcast the information to the users, and the user segment, consisting in the users themselves.

The WAAS Ground segment is composed of:[7]

  • 38 widely-spaced Wide-area Reference Stations (WRS), located in North America (continental U.S., Puerto Rico, Alaska, Canada and Mexico) and Hawaii: the WRS stations collect GPS data.
  • 3 WAAS Master Station (WMS): the WRS collected data are forwarded to the WAAS Master Station (WMS) via a terrestrial communications network. At the WMS, the WAAS augmentation messages are generated.
  • 6 Ground Uplink Stations (GUS): they are in charge of the transmission of the WAAS messages generated by WMS stations to the navigation payloads on Geostationary communications satellites for rebroadcast to the users.
  • 2 Operational Control Centers (OCC), used to monitor the system performance and to carry out the necessary corrective and periodic maintenance operations located at the National Operations and Control Center (NOCC) and Pacific Operations Control Center (POCC).[8]
  • WAAS terrestrial communications network that provides the communications link between the WAAS subsystems for transmitting WAAS data.

List of reference stations

WAAS Reference Station Barrow, Alaska

The WAAS Wide-area Reference Stations (WRS) are located in USA, Canada, Mexico and Puerto Rico. Regarding the US stations, each of the FAA Air Traffic Control Centers, but Indianapolis, hosts one WRS.[9]

For completeness, the list of WRS stations with their coordinates are shown in the next table (taken from WAAS article in Wikipedia[10] ):

City ICAO airport code Location Elevation
Bethel, Alaska PABE 60.787898226ºN 161.841705626ºW 52.202 m
Billings, Montana KBIL 45.803726761ºN 108.539727967ºW 1112.261 m
Barrow, Alaska PABR 71.282786134ºN 156.789914977ºW 15.581 m
Cold Bay, Alaska PACD 55.200376531ºN 162.718528459ºW 53.652 m
Fairbanks, Alaska PAFA 64.809686817ºN 147.847403468ºW 149.888 m
Honolulu, Hawaii PHNL 21.312783159ºN 157.920876933ºW 24.922 m
Juneau, Alaska PAJN 58.362530123ºN 134.585495176ºW 16.024 m
Mérida, Yucatán (Mexico) MMMD 20.931919004ºN 89.662872977ºW 29.157 m
Mexico City (Mexico) MMMX 19.431653193ºN 99.068389463ºW 2236.638 m
Puerto Vallarta, Jalisco (Mexico) MMPR 20.679034758ºN 105.249200735ºW 11.077 m
San José del Cabo, Baja California (Mexico) MMSD 23.160416093ºN 109.717667886ºW 104.286 m
Tapachula, Chiapas (Mexico) MMTP 14.791340027ºN 92.367991216ºW 54.922 m
Kotzebue, Alaska PAOT 66.887352636ºN 162.611355542ºW 10.911 m
Iqaluit, Nunavut (Canada) CYFB 63.731446844ºN 68.543393603ºW 9.998 m
Gander, Newfoundland and Labrador (Canada) CYQX 48.966447828ºN 54.597532074ºW 146.891 m
Winnipeg, Manitoba (Canada) CYWG 49.900606898ºN 97.259280113ºW 222.046 m
Goose Bay, Newfoundland and Labrador(Canada) CYYR 53.308720955ºN 60.419401330ºW 37.842 m
Albuquerque, New Mexico KZAB 35.173560874ºN 106.567308273ºW 1620.154 m
Anchorage, Alaska PAZA 61.229174557ºN 149.780364869ºW 80.654 m
Aurora, Illinois KZAU 41.782616622ºN 88.331308050ºW 195.922 m
Nashua, New Hampshire KZBW 42.735705193ºN 71.480378445ºW 39.141 m
Leesburg, Virginia KZDC 39.101556058ºN 77.542750106ºW 80.085 m
Longmont, Colorado KZDV 40.187286655ºN 105.127181633ºW 1541.389 m
Fort Worth, Texas KZFW 32.830614792ºN 97.066488376ºW 155.604 m
Houston, Texas KZHU 29.961833882ºN 95.331462501ºW 10.947 m
Hilliard, Florida KZJX 30.698824796ºN 81.908178358ºW 2.141 m
Olathe, Kansas KZKC 38.880140378ºN 94.790729104ºW 305.814 m
Palmdale, California KZLA 34.603503189ºN 118.083872233ºW 763.546 m
Salt Lake City, Utah KZLC 40.786007936ºN 111.952158417ºW 1287.420 m
Miami, Florida KZMA 25.824644475ºN 80.319246501ºW -7.882 m
Memphis, Tennessee KZME 35.067423639ºN 89.955391700ºW 68.788 m
Farmington, Minnesota KZMP 44.637444415ºN 93.152039309ºW 262.667 m
Ronkonkoma, New York KZNY 40.784293219ºN 73.097181151ºW 6.108 m
Fremont, California KZOA 37.543019928ºN 122.015922570ºW -3.459 m
Oberlin, Ohio KZOB 41.297135898ºN 82.206391657ºW 224.115 m
Auburn, Washington KZSE 47.286919203ºN 122.188372739ºW 82.128 m
San Juan, Puerto Rico TJZS 18.431249167ºN 65.993480433ºW -28.547 m
Hampton, Georgia KZTL 33.379671593ºN 84.296678124ºW 261.142 m