Magnetic Question

Sport Pilot

Sport Pilot

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Fellow pilots,

Before I begin, I am a student pilot.

I have a question about Magnetics’ as it relates to aviation.

I understand that the TRUE COURSE is measured by the plotter on a sectional. I also understand that doing a wind correction gives you the TRUE HEADING.

Here is what I do not understand. I am reading that the MAGNETIC COURSE is TRUE COURSE corrected for magnetic variation. But the MAGNETIC HEADING is found by TRUE HEADING corrected for magnetic variation.

The magnetic variation is from the isogonic lines (East is least; West is best).

So if the true course is 203 degrees and magnetic variation is +5 is 208 MAGENTIC COURSE?

So if the true heading is 203 degrees and magnetic variation is +5 is 208 is MAGNETIC HEADING?
 
Correct. MAGNETIC COURSE is TRUE COURSE corrected for MAGNETIC VARIATION. MAGNETIC HEADING is your MAGNETIC COURSE, corrected for wind.

True course <the course you plot on the sectional> (-E)(+W)VAR = Magnetic Course
Magnetic Course (-L)(+R)Wind correction angle = Magnetic Heading
Magnetic Heading (+)(-) Deviation = Compass Heading

Hope his helps.
 
It is important to remember that the only accurate item in a course-heading calculation is true course as measured with a plotter on a chart. Variation changes with location, and the variation shown on charts is updated maybe every ten years...it is rarely accurate. Just as an example, find an isogonic line on a sectional and note its variation, then find a nearby VOR/VORTAC and check the difference between its 000 degree radial and true north, Throw in the compass deviation caused by electrical influences in the airplane and the final answer is a wild guess....but for knowledge test purposes (not real-life flying) the assumption is that everything is pin-point accurate.

Bob Gardner
 
True course <the course you plot on the sectional> (-E)(+W)VAR = Magnetic Course
Magnetic Course (-L)(+R)Wind correction angle = Magnetic Heading
Magnetic Heading (+)(-) Deviation = Compass Heading
Click to expand...

But with the true course, do I need to find the True Heading first by the wind correction giving me the Magnetic Heading?
 

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Sport Pilot said:
But with the true course, do I need to find the True Heading first by the wind correction giving me the Magnetic Heading?
Click to expand...
Use the same units for wind or you'll be in trouble, i.e., magnetic wind direction or true.
 
Sport Pilot said:
But with the true course, do I need to find the True Heading first by the wind correction giving me the Magnetic Heading?
Click to expand...
No. They're two different things.

True Heading is just correcting your True Course for winds - that's it.

Magnetic Heading is the product of your True Course, correcting it for Magnetic Variation and THEN correcting it for wind. Honestly, I don't think I've ever used True Heading, because it's not taking Magnetic Variation into consideration.
 
RyanB,
Thanks for your explanation. It really helped out.
 
Ryanb said:
Honestly, I don't think I've ever used True Heading, because it's not taking Magnetic Variation into consideration.
Click to expand...
But it takes true wind direction into consideration. So, do you convert winds aloft to magnetic before the correction your way?
 
dtuuri said:
But it takes true wind direction into consideration. So, do you convert winds aloft to magnetic before the correction your way?
Click to expand...
Huh?

Does adding 1 + 2 give you a different result than 2 + 1? Doesn't matter which variable you calculate first, you'll still get the same end result.
 
So as pilots, Magnetic Heading is most important as it is the sum of everything.
 
Ryanb said:
Huh?

Does adding 1 + 2 give you a different result than 2 + 1? Doesn't matter which variable you calculate first, you'll still get the same end result.
Click to expand...
You can't mix 'em up. Think about it.
 
dtuuri said:
You can't mix 'em up. Think about it.
Click to expand...
I'm not sure what you're getting at. Whether or not you calculate the magnetic variation first or the wind correction angle first, you'll still end up with the same Magnetic Heading value.
 
Where are you getting your magnetic wind direction from (source) then?
 
I use foreflight. figures it all out for me. But for the OP, it is important to understand the concepts and how to do it. Life has become easier for us over the last 20 years though.
 
PaulS said:
I use foreflight. figures it all out for me. But for the OP, it is important to understand the concepts and how to do it. Life has become easier for us over the last 20 years though.
Click to expand...
Maybe you can help Ryanb and the OP. I've got to pull a rusty brake line out of my antique car. Not everyone's life is easier.
 
dtuuri said:
Where are you getting your magnetic wind direction from (source) then?
Click to expand...
I calculate it from a winds aloft forecast, interpolated for my cruising altitude.
 
But for the OP, it is important to understand the concepts and how to do it.
Click to expand...
I WANT to understand it because that's our (PILOT) nature. I NEED to understand it for my practical.
 
Sport Pilot said:
I understand that the TRUE COURSE is measured by the plotter on a sectional. I also understand that doing a wind correction gives you the TRUE HEADING.

Here is what I do not understand. I am reading that the MAGNETIC COURSE is TRUE COURSE corrected for magnetic variation. But the MAGNETIC HEADING is found by TRUE HEADING corrected for magnetic variation.

The magnetic variation is from the isogonic lines (East is least; West is best).

So if the true course is 203 degrees and magnetic variation is +5 is 208 MAGENTIC COURSE?

So if the true heading is 203 degrees and magnetic variation is +5 is 208 is MAGNETIC HEADING?
Click to expand...

It seems like you already understand it perfectly fine to me. What's the issue?
 
dtuuri said:
Then you do use the same units, but the OP didn't seem to know it's required.
Click to expand...
I'm still not sure what exactly you're talking about. It's a very simple calculation that I answered in the first reply.
 
Ryanb said:
I'm still not sure what exactly you're talking about. It's a very simple calculation that I answered in the first reply.
Click to expand...

Sport Pilot said:
But with the true course, do I need to find the True Heading first by the wind correction giving me the Magnetic Heading?
Click to expand...

Ryanb said:
No. They're two different things.
...
Magnetic Heading is the product of your True Course, correcting it for Magnetic Variation and THEN correcting it for wind. Honestly, I don't think I've ever used True Heading, because it's not taking Magnetic Variation into consideration.
Click to expand...
You correct true course for wind, using true winds aloft, THEN correct for variation. That's the way to teach a student. You can do it your way too, but you left out an important step — changing true wind direction to magnetic.
 
dtuuri said:


​
You correct true course for wind, using true winds aloft, THEN correct for variation. That's the way to teach a student. You can do it your way too, but you left out an important step — changing true wind direction to magnetic.
Click to expand...
As I said above, it all comes out to be the same number at the end. There’s several ways to skin the cat.
 
dtuuri,
Take true course from sectional, correct for winds, and then +/- for isogonic lines will give me what I need, correct?
 
Ryanb said:
As I said above, it all comes out to be the same number at the end. There’s several ways to skin the cat.
Click to expand...
No "it" doesn't. Yes, "your" way vs the standard way does, but it matters if you use true wind with magnetic course or vice versa.
 
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Sport Pilot said:
dtuuri,
Take true course from sectional, correct for winds, and then +/- for isogonic lines will give me what I need, correct?
Click to expand...
Yes, magnetic heading. Then add deviation for compass heading:

T+V+M+D+C = True virgins make dull company.
​
If you add variation to the wind first (like Ryanb) and mix it with true course:

Crabs + apples = Crab apples.
​
 
I am a student pilot about to complete my cross country. It has been a long road but I am almost there. I don't want to get into who's right and who's wrong; I just want the answer to get my feet off the ground.
Thank you guys!
 
dtuuri said:
Yes, magnetic heading. Then add deviation for compass heading:

T+V+M+D+C = True virgins make dull company.
​
If you add variation to the wind first (like Ryanb) and mix it with true course:

Crabs + apples = Crab apples.
​
Click to expand...
Do it your way and I'll do it mine. I can assure you that it doesn't make a difference.
 
Sport Pilot said:
I am a student pilot about to complete my cross country. It has been a long road but I am almost there. I don't want to get into who's right and who's wrong; I just want the answer to get my feet off the ground.
Thank you guys!
Click to expand...
Suppose you have, say, 20* variation and add it to true wind direction then use that to calculate a WCA from true course. Don't you think that will be totally bogus? Then when you convert add true course to magnetic and add a bogus WCA, you'll be on your way to BF Egypt.
 
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...and if there was 0 wind with 0 correction, the magnetic heading and magnetic course would be the same?
 
Ryanb said:
So the only way to do something is the way that YOU do it, every other method is wrong. Got it!
Click to expand...
That's not what you don't get. You left out an important step for the OP, converting true wind to magnetic direction when you do it your way. Maybe this will help you both:

TC var MC dev = CC
TW var MW
TH var MH dev = CH
 
Last edited:
dtuuri said:
That's not what you don't get. You left out an important step for the OP, converting true wind to magnetic direction when you do it your way. Maybe this will help you both:

TC var MC dev = CC
TW.....MW
TH var MH dev = CH
Click to expand...
You must’ve missed the first reply I made. I passed the PP check ride doing what I did here. The examiner who passed me, must be terribly mistaken as well.

Ryanb said:
True course <the course you plot on the sectional> (-E)(+W)VAR = Magnetic Course
Magnetic Course (-L)(+R)Wind correction angle = Magnetic Heading
Magnetic Heading (+)(-) Deviation = Compass Heading
Click to expand...
 
Ryanb said:
You must’ve missed the first reply I made. I passed the PP check ride doing what I did here. The examiner who passed me, must be terribly mistaken as well.
Click to expand...
I didn't have an issue with that post. It was Post #7 in answer to the OP asking if he had to take TH "first" to get MH. Since he is using winds aloft which are true, the answer is "yes", but you told him no. Then you didn't say until I intervened that you actually convert true wind to magnetic when you make the wca calculation.
 
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