Track as 0 degrees or 360 degrees?

[gleff]

Do aircraft transmit their track as 0 degrees, or 360 degrees when heading north?

I'm using a separate icon for every degree when plotting on google maps which essentially starts at 0.png, all the way up to 359.png.  I just noticed in my webserver logs that there's been numerous instances where 360.png was not found.  I would have thought they'd transmit North as 0 degrees, rather than 360 degrees. 

[DaveReid]

Do aircraft transmit their track as 0 degrees, or 360 degrees when heading north?

I'm using a separate icon for every degree when plotting on google maps which essentially starts at 0.png, all the way up to 359.png.  I just noticed in my webserver logs that there's been numerous instances where 360.png was not found.  I would have thought they'd transmit North as 0 degrees, rather than 360 degrees.

Aircraft don't transmit their track at all when airborne - that information is calculated by the receiving software, so it's up to the latter how it chooses to display it.

If it's any help, the corresponding encoding for heading (which some aircraft do send) uses 10 bits and therefore allows for values from 0 to 359.6484375°.

[gleff]

Ahh Okay thanks..  I also just remembered that I'm rounding to the nearest degree so if I get 359.6 ° then it will round up to 360 °.

All makes sense now.  Cheers

[DaveReid]

Ahh Okay thanks..  I also just remembered that I'm rounding to the nearest degree so if I get 359.6 ° then it will round up to 360 °.

That appears to be the same approach as is taken by the RadarBox software, where I'm currently seeing values from 000° to 360°.

Personally, it seems rather odd to have 361 discrete values for track in whole degrees.

[Runway 31]

ATC when giving it as a heading detail 360 degrees.