Recently I wrote an article for Aero Connections magazine, which described a handy program, ulnav, which can be a great help in the planning phase of simple or complex cross-country flights. This page is designed to support the use of the program. Unfortunately, the article got so severely cut it editing that what remained was not all that useful. Below find a link to the original version of the article:

•  Original Article Text - use this link to get a copy of the original article manuscript (in PDF format). Reading the article will require that you have a copy of the Adobe  Acrobat Reader software. If you don't already have the Reader installed, you can download it for free from the Acrobat Reader link.

Downloading the Software

Prior to actually downloading the software, prepare a folder to hold the program and its accessory files:

• Open your Windows Explorer program
• Left-click on C: or Local Drive C:
• Left-click FILE
• Left-click New
• Left-click Folder
• When the new folder icon appears, type ulnav and ENTER
• Exit Windows Explorer....

Once download is complete, start Windows Explorer, go to the ULNAV folder and double-click the ulnav.zip file/folder icon. With most current versions of Windows, this will "unzip" the file. Windows Explorer should now show the following list of files in ULNAV (not necessarily in this order):

mich.lmk - a sample airport file

ulnav.exe - the actual navigation program.

ulnav.cfg - program configuration file

ulnav.zip - your original downloaded file

Running ULNAV:

• Click on Start

• Click on Run

• Type c:\ulnav\ulnav and ENTER

Making Your Own Airport Files

The program comes with a sample airport file (mich.lmk), but you will obviously want a file or files customized for the area in which you fly. You can have multiple files if needs be. For example, I use my Michigan file for most of my flying, but I have another file (florida.lmk) that I use when doing flying vacations in Florida.

The *.lmk airport files are straight "text" files with a common format. To look at the format, use your NOTEPAD program (look under Accessories in the Program Menu) to look at the mich.lmk file. Remember, we are going to LOOK at the file. If you accidentally make changes in the file, exit Notepad without saving the changes. If you save any accidental changes, it is quite possible that you will screw things up! OK, here's what you should see when you open the mich.lmk file with Notepad:

"MICHIGAN #1"
MASON JEWETT,        4233.95,    8425.45
*
*
*
VAN WERT [OH],       4051.85,    8436.21

For easy reading, I use UPPERCASE for all my files, but the choice is up to you.  The first line of the file, "MICHIGAN #1" is the header for the file and it must be there. What is more, it must be enclosed in quotation marks as shown. The header can be anything you want it to be, as it is there for you to known what file you might be working with.

All the rest of the lines in the file are devoted to individual airports or landmarks and they all have the same format. In the case of the example shown above, the first and last entry in the file are shown and the asterisks simply represent all the other entries, which you will see, but which I have left out for clarity. Just for the record, the first airport entry in the file will be numbered 0 and I would suggest that you put your home field in first place. All the remaining airports will numbered in order of their appearance or position in the file. For airports in a single state, I usually alphabetize to make it easier to browse through the on-screen display. Once you have created a file, lines can be moved around using the editing functions included with notepad. OK, now lets look at the formatting for each airport entry (one line in the file).

AIRPORT NAME - this is the first entry on each line and it can be almost anything you want except that the entry should not contain any punctuation - particularly commas or periods! The name entry can be up to 20 characters in length. You have lots of flexibility here as you can use the actual name of the airport or the name of the closest community/town. I use either format, depending on where I am. Local airports, that I am particularly familiar with, I tend to label using the actual name of the field. In other cases, I will use the name of the nearest town as it is easier to remember when I am not familiar with the airports. Each airport name should be followed by a comma, as shown above, to separate it from the other information on the line.

In the case of airports in the file that may be in another state, I typically use the two-letter state abbreviation in square brackets (see the example of VAN WERT [OH] above). My "Michigan" file contains several airports in Ohio and Indiana, simply because I commonly fly there via Michigan airports and it doesn't make sense to put then in another file. On the other hand, I keep all the Florida airports in their own file because I don't get there via Michigan or other intervening states. Occasionally you will want to include useful landmarks in the file in addition to airports. I enclose the entire name of a landmark in square brackets [XXXX] so that I don't mistake the landmark for an airport when doing flight planning!

LATITUDE - the 4233.95 entry in the first line (Mason Jewitt) is the latitude of Mason Jewitt Field. In this case:

4233.95 = 42 degrees
                33.95 minutes
                NORTH

Note that I have use two decimal digits for the minute value. This is typically more than enough precision for our purposes, but many airport guides now feature three or four-digit precision. You can round-off to two digits or use the three or four decimal-place values - the program doesn't care! What is important is that the latitude be followed by a comma to separate the entry from the rest of the data on the line!

LONGITUDE - the 8425.45 value on the Mason Jewitt line is the longitude of the airport:

8425.45 = 84 degrees
                25.45 minutes
                WEST

Each airport or landmark will have one entry, formatted as shown. Each file can have as many as 75 such entries. If you have more, the program will function, but the airport display will scroll the early entries off the screen. If there are more than 100 entries, the program will crash! No harm done, but a waste of effort!

Longitude and Latitude Data

Longitude and latitude data for airports are available in a wide range of airport guides. Many state aeronautical commissions publish airport guides for their state and these guides are now commonly available on-line. Many of these guides include ultralight flight parks and airstrips. Another on-line source is  Air Nav, a site that gives you access to almost any licensed airport.

Ultralight strips that are not in any of the readily available guides present a problem, as do landmarks that you may wish to include. There are several ways to get the longitude and latitude for such locations:

• In the case of an ultralight flight park or airstrip, calling the owner may supply the numbers you need.

• If the location can be accurately plotted on a standard aeronautical chart, you can get the longitude and latitude from the chart. Be aware that this is an error-prone exercise to double and triple-check your determination.

• Many road atlas programs, such as DeLorme's Road Atlas USA^TM, will generate longitude and latitude data directly from the cursor position. The DeLorme product includes a very large number of small airstrips, plotted with precision, and often landmarks can be located as well.

• Published DeLorme county atlases, available for most states, include small airstrips and lots of landmark data. Reading longitude and latitude is easier and less prone to error than in the case of FAA sectionals or state aeronautical charts.

• Visit the spot, with your GPS in hand, and record the data!

I hope you enjoy the program and if there are questions or issues, don't hesitate to e-mail me.