Airport/Navaid filter for the Garmin GPS

(c) Andrew Sarangan, 2004

Filtering Method

The filtering can be done in one of several different ways:

--Region

Specify three or more reference points that form the corners of a geographic region and get a listing of all the waypoints that fall within that region

--Route

Specify a route by listing several reference points along the route and get all the waypoints that fall within a specified distance on either side of that route. Note that the route used is the great circle route, and therefore it may not always appear as a straight line.

--Radius

Get all the waypoints that fall within a certain radius of a specified location (or locations).

--State(s)

Select waypoints by state (or states).

--No Filter

If you select this, you will get everything that is on the database (which is huge).

Reference Points

These are the identifiers that defines the filtering area. These identifiers can be airports, navaids, fixes, waypoints or a mixture of these. You must use the official FAA identifiers (without the leading K if they are airports). Both upper and lower cases letters are treated as equal. These identifiers are searched in the airport database. If they are not found there, the navaid database is searched next. Finally, the fix database is searched. In many cases, the same identifier is used for the airport as well as the navaid. In such cases, it is the airport that gets selected as the valid identifier. Alternatively, if you are filtering by state, you must use the two-letter state abbreviations. Use OU as the abbreviation for locations outside the United States (yes, there are FAA facilities outside the U.S.)

Landing Facilities

Once you have selected the filtering method, you can choose if you want public, private or both types of airports selected.

You can also choose regular airports, seaplane base, heliport etc...

These two selection mechanisms are cumulative. That means, you can choose private seaplane bases, or you can choose public gliderports etc..

Prefix is a two-character string that specifies how you want your selections represented in the GPS. This string is simply attached to the beginning of the official identifiers. I like to use A- for airports. For example, LAX airport will appear as A-LAX. You also have the flexibility to choose different prefixes for different types of airports. For example, A- could be used for airports, and G- could be used for gliderports. This way they will be grouped separately making it easier for you to scroll through and identify them in your GPS.

Using the Symbol, you can also choose how you want your selections displayed on your GPS. The Garmin 12 has 16 different picture representations for the waypoints. Other models of Garmin might have slightly different picture representations, so you may have to experiment with it a little to get the correct symbols you want.

Along with the lat/long data, a brief description of each landing facility will also be used. This includes the airport name (truncated to fit the allocated space) and the airport elevation.

Navigational Facilities

You can choose navigational facilities, just like the landing facilities. These are divided into public, private and both, and further subdivided into different types. You can choose prefixes and symbols for each navigational facility.

Note that fixes and waypoints can only use a single-character prefix. This is due to the internal character limitation of the GPS.

Along with the lat/long data, a brief description of each navigational facility will also be used. This includes the name of the facility (truncated to fit the allocated space) and the frequency.

Obstructions

You can also choose antennas (obstructions) based on their height above ground level (AGL) or above sea level (MSL).

Canada

A limited number of Canadian airports can be chosen. The source is a US military database, DAFIF (Digital Aeronautical Flight Information File).

Output

There are two ways to look at your output. If you select 'Plot", you can see your data plotted on a U.S. map (just like the examples shown in this file). It also shows the number of selections made (to determine if it will fit in your GPS). Once you are satisfied that this is what you want, select 'Text'. This gives you the text file to use as input for your Garmin software. To save the file, point to the middle of the screen and right click your mouse. Then select 'View Source', and save the file.

Only the following two Garmin software (shareware) can be used:

Note that Waypoint+ does not recognize different symbols. All your data will be shown with a single picture representation. This is due to limitation of that program.

Gatrip is a better program. It will recognize different symbols.

If you want to read more about GPS in aviation, here is an excellent website.