Everyone acknowledges that GPS is a wonderful invention. It has replaced older, less capable technologies while finding new applications, thanks to exceptional attributes and affordability. Even so, and despite its relatively recent introduction, improvements have already been conceived and introduced. The space-based augmentation system called WAAS is one of the more important ones, but others are on the way.

WAAS is now a fact of life, with ground-based augmentation systems (GBAS) just now beginning to be installed. Outside the United States other augmentation systems are being fielded, including EGNOS in Europe, MSAS in Japan, and GAGAN in India. New satellite constellations that augment or compete with GPS – time will tell – are being established or reinforced: Europe's Galileo, China's Compass, and Russia's GLONASS. In GPS's space segment, the satellites that transmit the all-important reference signals for position determination are being updated, launch-by-launch, and a second signal frequency is being introduced to improve accuracy. This same tendency for change holds true, by the way, for areas other than navigation; e.g., new surveillance technologies like ADS-B for which GPS/WAAS is an enabler.

With so much changing, the only way to keep up is to follow its evolution on a regular basis. Monthly trade journals are one means of doing so, but an effective and affordable alternative is to monitor websites that present the most current information on these issues, both on a reporting and editorial basis. To this end, we offer web pointers to some of our favorite sites. We've found these to be of value when seeking insight regarding navigation, surveillance, and related aviation issues. The list is not all-inclusive, and it's highly likely others – either already established or soon to be launched – are or will be out there. If we've overlooked a site for which you have a high opinion, please let us know so it can find its way into an updated version of this list sometime soon.

• GPS Daily - A general GPS-related e-newsletter
  
• GPS World - A general e-newsletter that contains a section on "Avionics and Transportation"
  
• U.S. Government GPS website developed by the National Space-Based Positioning, Navigation, and Timing Coordination Office
  
• Portion of FAA website addressing navigation services and issues, including GPS
  
• The FAA's Surveillance and Broadcast Services (ADS-B) program office
  • General Information and FAQ
  • ADS-B Schedule
  • ADS-B Coverage
  • Key Site Information
    • Miami, FL
    • Louisville, KY
    • Gulf of Mexico
    • Philadelphia, PA
    • Juneau, AK
• EGNOS resource and newsletter from the European Space Agency (ESA)
  
• Airspace and navigation resource from EUROCONTROL
  
• Projects and initiatives of Airservices Australia, including efforts towards ADS-B and GBAS
  
• FAA-sponsored home page for RTCA's ADS-B support effort (via committee SC-186 and its working groups)
  

• HAI - Helicopter Association International
  
• AEA - Aircraft Electronics Association
  
• ALEA - Airborne Law Enforcement Association
  
• NBAA - National Business Aviation Association
  
• AOPA - Aircraft Owners and Pilots Association
  
• ATA - Air Transport Association
  

• Aero-News Network
  

• Stork Fokker
  
• Septentrio
  
• ECT-Industries
  
• TRIG Avionics
  
• Becher Avionics
  
• Sandel
  
• Chelton
  
• Shadin
  
• Honeywell
  
• Trimble
  

• Eurocopter
  
• AgustaWestland
  
• Robinson Helicopter Company
  
• Schweizer Aircraft
  
• Bell Helicopter (U.S. Helicopter)
  
• Daher-Socata
  
• Lockheed Martin
  
• RUAG