In ,
karel adams wrote:

Every version of FS I have known has a file called MAGDEC.BGL
In FS2002 it is FS2002/SCENERY/MAGDEC.BGL
It's size has remained constant since 5.1 and I reckon
the contents haven't changed much either...
This file must contain data for magnetic variation
i.e. by reading this file it should be possible
to determine the magvar for a given longitude/lattitude.
Does anyone know how to do this?
In other words how is the data organised in the file?
Maybe a bit of code that actually reads this file?

Or is there a place on the web where the various
.BGL formats are explained?
Somewhere on flighsim.com praps?

TIA for any hint,
Karel Adams

Somebody once released details of the FS5.1 magvars, extracted from the .bgl and
converted to text file format. I had a copy of it once but can't remember where
I downloaded it from, nor where I've put it.

Apparently, people did notice differences in the magvars when FS95 was released,
so maybe more have happened since. Perhaps it would be possible for the values
to change but the file size stays the same because the data is in fields, padded
as necessary? It's not clear how the data extraction was done though, so
repeating the task for a newer version of the file means working that out for
yourself.

What exactly would you need the data for?

Does the Jeppeson database provided with 2002 not list magvars for the places
you're interested in?


--�
regards,

Mark