Problem: Aircraft navigation equipment is calibrated to magnetic north. Maps and charts, including our F10 map, are drawn with respect to geographic north. Depending on where you are on the globe, the difference between these can be substantial.
Why we care: When using the F10 map to navigate, you will always find geographic (true) bearings. If you want to go to that place, you will need to convert to a magnetic bearing. Also, when the F10 map reports the CVN's heading, it is reporting the true heading. When setting your CSEL for BRC, you will need to convert it to a magnetic heading.
How: You have to know the magnetic variation (MVAR) where you are. Fortunately, it's not that hard, and it remains relatively constant for a given area.
How to find it: Your Hornet provides it within the HSI page! On the HSI page, click DATA, then click A/C. The MVAR value for your current longitude is shown.
- HSI DATA AC.jpg (70.64 KiB) Viewed 3838 times
Real world pilots use a number of memory aids to remember how to convert from map-to-compass (true to magnetic) or compass-to-map. Since we would only really ever need to go map-to-compass, the aid that works is, "East is least, West is best." That means subtract for a MVAR E, add for a MVAR W.
In DCS World, you can pretty much just remember these values for whatever map you're in.
Caucuses: -6
Nellis: -12
Persian Gulf: -1
Trivia
1. The magnetic north pole is constantly slowly shifting position, so MVAR changes over time in the real world, but we're talking on the order of decades.
2. Real world runway markings are magnetic headings. E.g., Runway 21 should be a final heading of 210 +/- 5.
3. As MVAR shifts over time, sometimes airports actually have to change their runway numbers. When I first moved to Ft. Lauderdale in 2005, the runways at FLL were 09/27. They are now 10/28. In DCS World, runway markings are not particularly reliable, like at KBL where the runway heading for 07 is actually 064, but the kneeboard will provide actual magnetic runway headings (and elevations) for each field if needed.
Bonus
Ever wanted to change the BALT warning altitude? You just found it, on that same page. It always defaults to 5000 ft. when you start up the plane. Click the BARO button to change it to whatever you want on the UFC. (The RADAR warning altitude cannot be changed here. You have to do it with the gauge knob.)
