Coordinates

Background

Hot air balloon competition uses a specific type of coordinate system rather than latitude/longitude. This system makes math and quick judgement easier. It is called Universal Transverse Mercator or UTMs.

UTM coordinates function based on a grid system split by zones. An example of these zones is shown on the right as overlaid on the continental US.

Within each zone, the map is divided into 1 meter by 1 meter squares. These squares are assigned a number, which defines the coordinate.

Source: Public Domain

The Coordinate

This is what a UTM coordinate looks like:

34U 555346 5503952

It is defined by 3 distinct numbers: the zone, the easting, and the northing. The 34U denotes the zone. This has been discussed above. The easting defines the "Left/Right" or east/west position. In the example, this is the 555346 number. The northing defines the "Up/Down" or north/south position. In the example, this is the 5503952 number. Notice that the northing is longer, which makes sense when looking at the zone reference.

Using the easting, I will explain the math a little more. Each number corresponds to a degree of ten. So, the 6 is 1 meter, the 4 is 10 meters, the 3 is 100 meters, and so on. This means that the coordinate 555446 and 555346 can quickly be determined to be 100 meters off, because the 100 meter digit is wrong. I have confirmed this using Google Earth Pro.

So How do Balloons Use It?

The full coordinate can be quite clumsy in the UTM system, because it is composed of 16 digits not counting spaces. That said, some of these digits are so astronomically large when compared to the scale of balloon competitions, that they are not necessary. At the same time, 1 m precision is very difficult to achieve, even with modern GPS technology.

As a result of these challenges, balloons use a 4/4 coordinate system. This means 4 digits from the easting and 4 from the northing. While this may sound intuitive, it can be a little confusing. This is because the 4 digits do not include the ones; they are the 10, 100, 1000, and 10000 meter digits. This serves to give coordinates 10 meters of variance and forgiveness when placing a physical target (which is permitted by the rules), and shortens the necessary numbers.

A more clear and technical explanation of the UTM system

A video I made on how to convert UTM coordinates to Google Maps for Ballooning

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