I see, so it's a procedural language that is well understood by those who fly (not just some semi-structured data or ontology). This is a great example of the advantage of domain experience. Thanks for sharing!
> a procedural language that is well understood by those who fly
That is a great way to describe it!
Of course it is all just rows in a CSV file, but yes, it is a set of instructions for how to generate a map.
In fact the pilot's maps were being drawn long before the computer era. Apparently the first FAA sectional chart was published in 1930! So the data format was derived from what must have been human-readable descriptions of what to plot on the map using a compass and straightedge.
I just remembered a quirk of the Australian airspace data. Sometimes they want you to draw a direct line from point F to point G, but there were two different kinds of straight lines. They may ask for a great circle, a straight path on the surface of the Earth. Or a rhumb line, which looks straight on a Mercator projection but is a curved path on the Earth.
You would often have some of each in the very same boundary description!
For anyone curious about this stuff, I recommend a visit to your local municipal airport and stop by the pilot shop to buy a sectional chart of your area.
Paper charts are great (they're fairly cheap and printed quite nicely in the USA at least) but you can get a good look at these boundaries through online charts.
Stratoscope|1 year ago
That is a great way to describe it!
Of course it is all just rows in a CSV file, but yes, it is a set of instructions for how to generate a map.
In fact the pilot's maps were being drawn long before the computer era. Apparently the first FAA sectional chart was published in 1930! So the data format was derived from what must have been human-readable descriptions of what to plot on the map using a compass and straightedge.
I just remembered a quirk of the Australian airspace data. Sometimes they want you to draw a direct line from point F to point G, but there were two different kinds of straight lines. They may ask for a great circle, a straight path on the surface of the Earth. Or a rhumb line, which looks straight on a Mercator projection but is a curved path on the Earth.
You would often have some of each in the very same boundary description!
For anyone curious about this stuff, I recommend a visit to your local municipal airport and stop by the pilot shop to buy a sectional chart of your area.
tass|1 year ago
https://skyvector.com is a good way to view these.