GPS - Global Positioning System

One of the most fascinating new products to be introduced to the public at the end of the twentieth century is the GPS. To many, it is still a specialty item, but to me it has become a very useful tool as well as a fun toy that answers the immortal question, "Are we there yet?"

The Global Positioning system consists of a constellation of twenty-four satellites orbiting at an altitude of 10,988 nautical miles above the earth. A GPS receiver compares the difference in time that signals take to arrive from three or more of those satellites to determine where it is, with an accuracy of about 50 feet. GPS satellites are also used as an accurate reference for time and radio frequencies by a variety of users.

In the 1980's, I installed a Loran in my Piper Tri-Pacer. It let me fly directly to any latitude/longitude co-ordinates that I would punch into it's keyboard. Along the way it gave a constant readout of groundspeed, distance to our destination, and the estimated time of arrival. Having all that information readily available was extremely useful and I quickly became spoiled by my first taste of global navigation.

Though Loran is extremely accurate, it uses very low frequencies that were susceptible to interference from rain, lightning, and even the laptop computer I sometimes used. It was permanently mounted in my airplane's instrument panel, but I loved to fly with it. Later, in the 1990's, GPS receivers arrived on the scene and I soon owned a handheld Magellan SkyBlazer LT. It had all the capabilities of Loran and more, including a database of all airports located in the western hemisphere. It operated on higher frequencies and used signals from twenty-four satellites, so it was much more reliable in all types of weather conditions. Since it was handheld, I was soon using it, not only for flying all over the country, but also to find remote transmitter sites to which I was driving, or marking the location of a hotel so I could find my way back. Nowadays we even use GPS satellites as a frequency reference for broadcast transmitters.

These days Sue and I are using a Magellan 315 - inexpensive yet much more sensitive than the first generation SkyBlazer. Many might prefer the fancier units on the market with built-in moving maps and other accessories, but I'm a numbers guy who simply wants the bottom line. I prefer flying with a numerical display that gives heading, bearing, speed and distance. Sue, on the other hand, likes the graphic display that shows the position of our plane or car superimposed on the course we should be following. No matter which display we use, our GPS gives us the peace of mind that comes from knowing we are where we belong - something that's very important in post 9/11 aviation.

Recently we have discovered geocaching and our past experience with GPS made us fit right in. It's a hobby in which we use our GPS to locate any of over 60,000 1,000,000 "caches" hidden around the world. These are mostly small containers, often filled with items that can be traded. We've found it to be a great way to get exercise and fresh air, learn about geography and history, and meet other geocachers. Now, if only our GPS could detect poison ivy......

Along with our Olympus digital camera, GPS has truly become a part of our everyday lives, as it has for farmers, truckers, and people from about every other walk of life. If you are not using it yet, you will very soon. ;)

Airplane page - Geocaching - Confessions of a Pilot
Gene & Sue's Home - GPS and Soaring