# Magnetic variation updates for FS9 and FSX!

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may I ask what the difference between magnetic and true is?

Joe Barton

The Earth in fact has two north poles. There is True North, which is what latitude and longitude are based on, or the grid pattern you see on a globe. The Earth rotates around this point too. But there is also a magnetic north (and south) pole, created by the swirling iron inside the Earth being slightly different than the axis of rotation. Magnetic north is about 500 miles off of true north. Magnetic north is what compasses operate off of. http://www.gcmap.com/mapui?P=82.7%b0N+114.4%b0W+-+90N+0W

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Eric Vander

Pilot and Controller Boston Virtual ATC

KATL - The plural form of cow.

KORD - Something you put in a power socket.

UNIT - Something of measure

My 747 Fuel Calculator

and it changes all the time right? Why do aircraft operate using magnetic course and not true? I thought true is more reliable

Joe Barton

and it changes all the time right? Why do aircraft operate using magnetic course and not true? I thought true is more reliable
I assume because for the aircraft to know where true north is, it needs a data base of where things are and know exactly where it is at that point in time. Like every system there can be errors involved (or always is so some extent). Magnetic north however you just need a compass ad even if all the aircrafts systems took a dive, the mag compass will not.

Jay Vorkapic

and it changes all the time right? Why do aircraft operate using magnetic course and not true? I thought true is more reliable
Because a compass works off of the Earth's magnetic field. I "believe" that on your modern aircraft avionics, the computer calculates your true heading based on your LAT/LONG position and your magnetic heading. However, some aircraft like your light GA and of cours sail planes don't have modern avionics to calculate this. Even when we did land navigation in the military, we would have to use magnetic heading, then convert using the mag dev to determine our "heading" on a map.

Jeremy "BZ" Bucholz

And to figure out the LAT/LONG you need GPS right?

Joe Barton

And to figure out the LAT/LONG you need GPS right?
No, INS also does it, it needs a starting Lat/Long and with gyroscopes and accelerometers it constantly calculates position with a error factor. Navaids (NDB, VOR, DME etc) with a database of their position also helps to locate position and reduce error.

Jay Vorkapic

commercial jets have gyroscopes? How I must sound stupid for not knowing that. Is navigating with magnetic course better than true course?

Joe Barton

No wonder I never lined up!

I clicked " update Magvar data" on the link and it downloaded a file called MagDec_Update.rar do I drop that file into FSX folder or am I supposed to extract something? It's not a .bgl file, it's a .rar is that correct? do i literally drop that file?

Mitch Brown

Private Pilot | Aerospace Engineering Major

.rar is like a .zip, you need to extract it first. Do a google search to find a utility that will do it for you.

Computer Specs: | Intel Core i7 920 @ 4.4 Ghz | nVidia GeForce 670 | 24 GB DDR3 Ram | Windows 7 Pro x64 |

www.rarlabs.com - winrar

Regards,
Alan Norris

Live Video Stream : http://www.twitch.tv/aystertv

ok, so I think I did it. Is there a way for me to know it worked?

Mitch Brown

Private Pilot | Aerospace Engineering Major

I've done this before and it worked but now with the latest AIRACS, for some reason it no longer works. I am way off center line!

/ CPU: Intel i7-9700K @4.9 / RAM: 32GB G.Skill 3200 / GPU: RTX 3080 10GB /

Kyle

I must try these !! Mark.

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