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Magnetic Variation
- Thread starter Pyscen
- Start date
The magvar in FSX Planner is based on what the SDK says:
-360.0 to 360.0 floating point value. Default = 0.0. East magvar is negative, West magvar is positive.
So unless the SDK documentation is incorrect then I believe FSX Planner displays the magvar correctly.
-Russell
Pyscen
Resource contributor
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- 3,040
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I have read that in a Magvar its represented positive when it is east and west magvar is - (negative). AirNav site has it positive Magvar for East and negative for West.
That was the reason for the question... but if Microsoft has switched it around that fine.. I was just wondering if that was the cause.
Thanks
That was the reason for the question... but if Microsoft has switched it around that fine.. I was just wondering if that was the cause.
Thanks
- Messages
- 8,893
MS has not switched it around. You are working from a Mag variance and not a Lat/Lon value.
If you work from a Mag value then you have to add when a E is showing.
AirNAV says for KRND
Variation: 07E (1985)
Runway 14R
Magnetic bearing: 143
True bearing: 150
Magnetic variation: 07E
However FS does not work off a Mag Value, it works off a TRUE value for the airport. The true value comes from the Lat/Lon of the airport which is North and West. N/W means a -7 from True North. So FS subtracts 7 (-7) from 150 and the runway adds 7 (07E) from 143 Mag.
The end result is the same value whether you add or subtract 7 and it is based on what part of a airport you are looking at (ARP Lat/Lon vs Mag runway data) and what number you used as a base number.
Many Users of FS no nothing about flying the old school way that we used many years ago. All we had was a Compass which later was followed by sounds of dots and dashes in my earphones so I knew if I was flying toward a radio signal on a center beam.
A Compass lead/lags and dips forward/backward (incased in fluid) so it was important to know in a turn if we were West or East (Isogonic zero). It was also important to know the Mag variance of a runway heading when using only a Compass to help get us to a airport runway when visiblity was less then severe clear. A Compass does not point to true north or to Mag north like so many think. It points to Mag south. Two like signs repel so the compass in your pocket has the pointer on the wrong end. The pointer end is the south end so it can point in what appears to be the correct direction. Tha tailend of a pocket compass is actually the positive or north end. Unlike signs attract, like signs repel.
You are not wrong in your thinking because you add 7 (to get True North) when Mag variance is E. However you subtract 7 when longitude of the land is W which is what FS uses for their Lat/Lon placement.
If you work from a Mag value then you have to add when a E is showing.
AirNAV says for KRND
Variation: 07E (1985)
Runway 14R
Magnetic bearing: 143
True bearing: 150
Magnetic variation: 07E
However FS does not work off a Mag Value, it works off a TRUE value for the airport. The true value comes from the Lat/Lon of the airport which is North and West. N/W means a -7 from True North. So FS subtracts 7 (-7) from 150 and the runway adds 7 (07E) from 143 Mag.
The end result is the same value whether you add or subtract 7 and it is based on what part of a airport you are looking at (ARP Lat/Lon vs Mag runway data) and what number you used as a base number.
Many Users of FS no nothing about flying the old school way that we used many years ago. All we had was a Compass which later was followed by sounds of dots and dashes in my earphones so I knew if I was flying toward a radio signal on a center beam.
A Compass lead/lags and dips forward/backward (incased in fluid) so it was important to know in a turn if we were West or East (Isogonic zero). It was also important to know the Mag variance of a runway heading when using only a Compass to help get us to a airport runway when visiblity was less then severe clear. A Compass does not point to true north or to Mag north like so many think. It points to Mag south. Two like signs repel so the compass in your pocket has the pointer on the wrong end. The pointer end is the south end so it can point in what appears to be the correct direction. Tha tailend of a pocket compass is actually the positive or north end. Unlike signs attract, like signs repel.
You are not wrong in your thinking because you add 7 (to get True North) when Mag variance is E. However you subtract 7 when longitude of the land is W which is what FS uses for their Lat/Lon placement.
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