How to find magnetic declination of a location?

I understand that to calibrate the Directional Gyro, you have to get the current heading from the course setter and then adjust that value using the magnetic declination for a location.

Where is this value obtained from?

I can see that just about everywhere in the Caucasus map is +6, but I'm just wondering how you get that data when in-plane. Is it something you would 'just know' before taking off, or should it be in a mission briefing?

Edited April 16, 2017 by imacken

I understand that to calibrate the Directional Gyro, you have to get the current heading from the course setter and then adjust that value using the magnetic declination for a location.

Where is this value obtained from?

I can see that just about everywhere in the Caucasus map is +6, but I'm just wondering how you get that data when in-plane. Is it something you would 'just know' before taking off, or should it be in a mission briefing?

As a follow up, why is the magnetic declination needed anyway?

If I am on a runway, and the external view shows I am on a heading of, say 84 degrees, and the heading from the course setter is also 84 degrees, why should I set the DG to 90 if the magnetic deviation is 6 degrees.?

That's published in many places, but especially in navigation charts. And that's also why charts have to be updated every now and then. I don't really know what year's declination matches current Caucasus map one as AFAIK it isn't changing with the years and DCS updates. IRL even runway headings have to be updated every now and then due to magnetic declination variation (I mean, actual paint on the runway).

 

 

Haven't found a pic of the navigation charts, if you are very interested I will take a pic of my own charts, but it's something like this, a line indicating declination for a certain area.

 

 

 

S!

As a follow up, why is the magnetic declination needed anyway?

If I am on a runway, and the external view shows I am on a heading of, say 84 degrees, and the heading from the course setter is also 84 degrees, why should I set the DG to 90 if the magnetic deviation is 6 degrees.?

It makes sense for long journeys. RWY headings are published, as well as painted in the tarmac, following actual compass reading so it includes magnetic deviation. Your reading in a compass, obviously, includes magnetic deviation. But, should you plan a long flight without bearing declination in mind, you can get badly lost IRL, especially in GA and VFR flights. You don't have an F10 map showing your position in a real aircraft, and GPS sometimes stop working for whatever reason. DCS just features the real deal, it's up to you using it as IRL or not.

 

 

S!

Thanks for that.

So, are you saying that I shouldn't add a magnetic declination to the course setter reading to input into the DG for short journeys?

Thanks for that.

So, are you saying that I shouldn't add a magnetic declination to the course setter reading to input into the DG for short journeys?

It's not necessary to do so, you will get to your destination the same, just a bit deviated. For a long and probably high altitude cruise it's quite necessary as you rely more on instruments and less in VFR chart. Anyway, as you can see, modern aircraft using IFR instruments, or pre-setted waypoints in any kind of inertial navigation system doesn't need that whatsoever. It's only worth using it for real VFR navigation and dead reckoning.

 

 

S!

OK, so now I am totally confused!

Using the Instant Action Free Flight Mission, I set the DG to 343 as per the reading on the course setter. All looks fine.

I turn to around 180 and land at Kobuleti which looks to be at around 70 degrees from the map. My plane is at 71 degrees on the runway according to the external view, but the DG says 85 degrees!

That can be a mix up of declination plus gyroscopic precession, provided you were absolutely precise the first time you set the compass.

 

 

S!

I was precise in setting it up, and have repeated the exercise getting a similar result. (Second time it was 18 degrees out!)

How can it go 15-18 degrees out just doing a landing?

I was precise in setting it up, and have repeated the exercise getting a similar result. (Second time it was 18 degrees out!)

How can it go 15-18 degrees out just doing a landing?

Gyroscopic precession. Even modern gyrocompasses are meant to be set every now and again using the regular spare compass.

 

 

S!

So where is it losing it in that short time - free flight, descent or actual landing? Seems like a lot in such a short space of time, doesn't it?

Like the artificial horizon, makes me wonder what the point of it is. The AH is kind of OK, as you have your eyes, but the direction gyro?

Don't know really for your case, but every manoeuvre adds a bit to the precession.

 

 

Make sure anyway you're setting it absolutely right. Bear in mind gyro works "the other way", reads to the right when you turn left and vice versa. It can be really confusing.

 

 

S!

The Directional Gyro or Heading Indicator is NOT a primary flight instrument. The compass is primary, the gyro simply makes it easier to monitor heading while accelerating/decelerating and during turns, but it must be reset to the compass heading often, especially after violent maneuvers... this is a museum piece after all :D

 

When talking about the Spit and other "less than modern aircraft" examples, one must realize there are only two primary flight instruments... The eyeballs, and the cheeks of the arse... and the latter isn't very precise because It's a SIM, not real life :D

Edited April 16, 2017 by jocko417

When talking about the Spit and other "less than modern aircraft" examples, one must realize there are only two primary flight instruments... The eyeballs, and the cheeks of the arse... and the latter isn't very precise because It's a SIM, not real life :D

:megalol: :megalol: :megalol: :thumbup:

 

 

S!

I was precise in setting it up, and have repeated the exercise getting a similar result. (Second time it was 18 degrees out!)

How can it go 15-18 degrees out just doing a landing?

 

When I was doing my license in the very first trainer, I needed to re-calibrate the DG every 15 minutes.

That should give you some indicator of how far it can wander.

 

I wouldnt worry too much about Mag variation (or as you call it Declination? I've never heard it called that before and I have 2 sets of ATPLs) is only a real issue if its over long distances of about 100-150NM +. ANd if you're flying VMC anyways, just look out the window.

 

Its actualyl a shame DCS doesnt publish a high-quality map for download for use in the sim for VFR and IFR work.

I wouldnt worry too much about Mag variation (or as you call it Declination? I've never heard it called that before and I have 2 sets of ATPLs) is only a real issue if its over long distances of about 100-150NM +. ANd if you're flying VMC anyways, just look out the window.

Yes, magnetic declination, or variation as you say.

 

https://en.wikipedia.org/wiki/Magnetic_declination

 

 

Personally I didn't think about that, in Spanish it's most usually called "declinación", but you're right may be in English is more commonly known as variation, though declination is still correct.

 

 

S!

I wouldnt worry too much about Mag variation (or as you call it Declination? I've never heard it called that before and I have 2 sets of ATPLs)

Strange, it's called Magnetic Declination in Chuck's Guide on Navigation p58.

https://en.wikipedia.org/wiki/Magnetic_declination

Edited July 4, 2017 by WildBillKelsoe

I think you will find that the magnetic variation was different in the 1940's WWII era than it is now in modern times. As I understand it, the variation changes over time. So the Normandy map should have different navigation in terms of magnetic variation than the more modern DCS maps. So, I suggest that the Normandy map should be subject to the magnetic variation of the time of WWII and not 2017.

How this may effect modern jet flying on the DCS Normandy map I am not sure.

Perhaps the Navigation map for WWII should be separate, bespoke to the 1940's and part of the WWII pack.

 

 

Happy landings,

Further to above, I have just had a look at my copy of an Ordinance Survey RAF (WAR) map from 1944 covering the Strait of Dover and Normandy, and the magnetic variation is shown as 8 degrees and 47 minutes.

 

 

I believe that the variation at the moment in 2017 for the same area is 0.1 degree.

 

 

That is a significant difference between 1944 and today.

 

 

 

P.S. I suggest that if DCS want to give us a Normandy map with a negligible variation, as per more modern times, then that would be fine, as long as we know one way or the other.

 

Happy landings,

Edited July 4, 2017 by 56RAF_Talisman

Here's a handy tool for calculating the magnetic declination at various places around the globe: https://www.ngdc.noaa.gov/geomag-web/#declination

 

I checked Bayeux, which gave a result of 0° 28' W (or 0.46° for the decimal degree folks), with an annual change of 9' (0.15°) East.

 

And as for not knowing the term declination despite having 2 ATPLs: terms used by pilots aren't necessarily the same as those used by surveyors or cartographers. Neither is wrong or right; they're just two different terms for the same thing.

The Directional Gyro or Heading Indicator is NOT a primary flight instrument. The compass is primary, the gyro simply makes it easier to monitor heading while accelerating/decelerating and during turns, but it must be reset to the compass heading often, especially after violent maneuvers... this is a museum piece after all :D

 

When talking about the Spit and other "less than modern aircraft" examples, one must realize there are only two primary flight instruments... The eyeballs, and the cheeks of the arse... and the latter isn't very precise because It's a SIM, not real life :D

 

And here we have the concept for the next great advance in computer simulation--a massage chair modified to simulate that 'seat of the pants' feel we've all been missing...

 

cheers

 

horseback

And here we have the concept for the next great advance in computer simulation--a massage chair modified to simulate that 'seat of the pants' feel we've all been missing...

 

cheers

 

horseback

 

 

 

Check this out:

 

 

https://dreamsimteam.blogspot.co.uk/p/simshaker.html

 

 

Good thread here:

 

 

https://forums.eagle.ru/showthread.php?t=134704

 

 

But be award it has been superseded by this:

 

 

https://forums.eagle.ru/showthread.php?t=175028

 

 

I have the Gametrix 908 jetseat and SimShaker and can recommend it very highly. I would not want to fly without it!

 

 

Happy landings,

I thought I chime in and give you a fairly simple explanation of Magnetic Variation or Declination. As an old soldier of foot (grunt), it was usually pretty mandatory to factor in mag variation in bearing calculation in land navigation, the same also does apply to all forms of nav.

 

1. Firstly, Mag Variation is the angle between Magnetic North and True North.

 

2. Mag North meaning, is the direction your compass points to.

 

3. True North in simple terms is the direction indicated on maps along a meridian or Easting towards the geographic North Pole depending on what type of map you use.

 

4. Magnetic North moves over time due to changes in the earths magnetic core and fields.

 

5. If you were to locate approximately where Mag North indicates to currently, it currently lies near Ellesmere Island in northern Canada .

 

6. On the maps I am used to using the mag variation is usually given as part of the map information, you as the user will then calculate it and use it in navigation.

 

7. A simple example of Map Information maybe: that the Map tells us that Variation moves 20 mils magnetic every 2 years, the variation at the time the map was made is 120 mils and it is now 6 years later ( the map is 6 years old). So you need to add 60 mils to the already variation of 120mils and get the answer as 180mils - this is your Variation.

 

8.For example : in calculating in the Southern Hemisphere, say in Australia, you use Grid to Magnetic you subtract the variation from your Grid calculation, and Magnetic to Grid you add it. Using the opposite for Northern hemisphere calculations. How you calculate also relys on what side of the Prime Meridian your on and which hemisphere you are in. Although there are more factors to consider apart from what I have explained, remember this is for simple understanding. If you want to learn more go and do a Nav course.

 

In remembering the method for calculating variation we used to use catchwords ,like “Grand Ma Sucks” = Grid to Magnetic Subtract, and “My Granny's Arse” = Magnetic to Grid add.

 

Hope this clears up some understanding.

Edited July 10, 2017 by Strut

Hello,

 

I can feel when I trim my plane during landing with my TFS seat. If you don't have tactile feedback in your seat, you are just sitting there.

 

DCS uses true north. If you don't believe it fly in the NTTR where it is very clear.

 

best wishes,