Navigating By Satellite

Navigating By Satellite

One of the greatest gifts that technology has given to travelers is the Global Positioning System (GPS). Twenty-four fixed satellites in the U.S. sky constantly beam radio signals toward Earth. Any GPS decoder can read those signals and tell you exactly where you are — even if you're moving in a car or an airplane!

Flying Words

Global Positioning System (GPS) is a space-based radio navigation system. Receivers in an aircraft, car, truck, train, ship, or on the ground use signals from satellites in the system to identify the receiver's position, velocity, and time. Software in the receiver interprets this information for the viewer.

GPS systems have been an option in cars for a few years now. You might have seen their screens, often in color, that show the car's location, nearby highways and roads, and even services such as motels and restaurants. Some even have voice software that will give you directions to where you want to go: "Turn left. No, your other left! Hey, watch out for that car. Uh-oh, it's a police car! Goodbye."

Today's aircraft can be fitted with GPS systems, too. In fact, portable units are available for planes at a relatively low cost ($500 to $2,000) that give you an amazing amount of information in your aircraft. Because they are portable you can use them in any type of airplane, including certified aircraft, the new light-sport planes, ultralights, or whatever you're flying.

What do GPS decoders show you? First, know that they include updatable software with information on airports and services. The decoder simply reads the signal from at least 5 of the 24 satellites. The good thing is that most units have a method of updating the data periodically to reflect changes in information. To answer the question, here's what you'll see on your GPS navigation system (depending on models):

  • Your plane's location over a map
  • The location of nearby airports (you can zoom in or out)
  • A list of nearby airports with relative locations and headings from you
  • Information about those airports (longitude, latitude, runway numbers, length, services, etc.)
  • The track you are flying (in degrees)
  • Flight planning information
  • Terrain (in color or shades of gray, depending on the model)
  • Land-based navigation aids (VORs, for example)
  • Outlines of controlled airspace (Class B, C, D, E, MOAs, etc.)
  • Other landmarks you might find on an aeronautical chart

Amazing! In addition, the latest models include a logbook for recording your flights, turn-by-turn directions for your flight plan, steering guidance (images of what your flight instruments should look like at any given time), various clocks and stopwatches, and much more. Some models include or can be retrofitted with databases that offer data more specific to automobile drivers or even boaters. They can be used anywhere!

You also can buy or rent aircraft with installed GPS systems, but they're more expensive. Some new systems now combine the traditional flight instruments onto a precision display panel for ultimate flying.

Knowledge Test

The sport-pilot knowledge test will ask few if any questions about GPS, but might ask many on other navigation systems. Make sure you've read your Aeronautical Information Manual (AIM) and other FAA publications.