Navigating Aircraft Navigation
Tuesday, 6th September 2011 by Chris Hannigan
Ever wonder how airline jets navigate the Earth from 30,000 feet on a cloudy day? The road maps provided by Google Maps wouldn’t be that relevant after all. The fact is most flights use radio navigation or GPS to find their way, and the radio navigation beacons they use are often visible in Google’s aerial and satellite imagery.
There are many types of radio beacons that are still in use today, but the majority are called VHF omnidirectional radio range or VORs. There are VOR stations all around the world, and given how widespread they are, you may well have passed one by without realising. The most common shape of the ground station resembles something of a bowling pin on a circular building. Pilots use the signal which is broadcast from these towers to fly to and from stations, therefore navigating across the sky.
Most beacons are located either at the airport, or placed out in far-away regions to avoid any interference on the signal. Some examples of these remote beacons include the Mitbee VOR in Oklahoma and the McComb VOR in Mississippi.
Take a look at the Babylon NDB (Non-directional beacon) on Long Island near New York. This beacon is situated right in the middle of a densely packed neighbourhood, and since it is only used as a directional beacon and not an omnidirectional range, it doesn’t have the classic bowling pin shape like the VORs. Due to the congestion around this beacon the FAA has declared its signal unusable beyond 15 nautical miles, which isn’t very far at all from a pilot’s point of view.
It’s not unusual to find beacons in very remote and rugged areas of the west of the US as well. Remember, some of the aeroplanes flying over these sparsely populated areas still need beacons to navigate, and thanks to this we see some interesting locations for these VORs. Out in the barren desert we can find beacons like the Sod House VOR in Nevada and the Peach Springs VOR in Arizona.
If you start looking deep in the mountains however, beacons like the Salmon VOR in Idaho and the Red Table VOR in Colorado (which is almost completely buried under the snow!) can be found. Notice how the Red Table VOR is painted in dark colours to contrast with the snow.
Pilots use these different types of beacons to navigate across the sky when they can’t see the ground. For example, let’s say we were going to pilot an aeroplane from Fort Lauderdale, Florida to Orlando, Florida. If we chose to use radio beacons for navigation, we could depart to the north using Fort Lauderdale’s own VOR as an initial direction (flying away from it), then switch over and fly towards the Palm Beach VOR as our initial waypoint.
After we cross over the Palm Beach VOR, a slight turn to the west and radio beacon frequency change would allow us to lock onto the Vero Beach VOR, then another shallow west turn and switch would take us directly to the Orlando VOR. During this entire flight, we would not need to see the ground at all (until we land anyway) just as long as we have functioning navigation equipment in the cockpit.
Aviation beacons are all around us, but the reality is that radio navigation is quickly becoming a thing of the past. With technological advances like GPS navigation, existing radio beacons are more commonly being used as a waypoints rather than actual navigation aids. For more information on aircraft instrument navigation, be sure to check out Wikipedia. If you would like to try and fly to a VOR yourself, try this free web based simulator.
Thanks to Runway Finder for helping me locate some of the above beacons.