What’s Up with the Headings?

What’s Up with the Headings?

If you’ve used the NerdNav and you’re not in the airline business or don’t do a lot of flying, the chances are that you’ve been surprised by the results that it can return. I know I was.

The problem is that most of us are used to seeing the world as a flat rectangular map, whereas the real world is spherical (OK not quite, but lets not get bogged down in that). I’m based in the UK, so if I think of travelling to Australia, from the flat earth map it looks like I have to travel in a roughly southeasterly direction. NerdNav says we have to go northeast. What’s that about?

Its the same thing if I want to go to Japan. Tokyo is about 10 degrees difference in latitude from my location, so it looks like we have to go east (more or less). NerdNav says its nearer to north than east.

Heading on a flat Earth

So here’s a screenshot from Google Earth that shows the path from London to Tokyo. As you can see the initial heading is northeast. This is what NerdNav tells you. Its the direction that you have to start travelling if you want to reach your destination by the shortest path, not what you’re used to seeing on a map.

spherical_heading

If you’ve done any air travel you’ve probably encountered this situation even if you didn’t know it. Its the reason why transatlantic flights pass near to Greenland. It’s the shortest route.

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