Why shouldn't aviation switch from magnetic to true north?

NoHeat

NoHeat

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With GPS navigation so common and cheap now, why do we still number our runways according to their magnetic direction? And the direction of our VOR radials and airways? And our headings on approach charts?

It's just a nuisance and an expense to keep updating these.

If aviation switched from magnetic to true, the few aviators who still navigate solely by magnetic compass (and gyros that are set by magnetic compass) would have to make adjustment for declination. As it is right now, everybody else, from pilots to chart makers to VOR technicians to runway painters must make the adjustment. And at a considerable cost that is never ending.

Just think of the ease and economy that would be gained by leaving everything numbered true, and leaving it that way.

So wouldn't it be cheaper and easier for most of the world of aviation to just switch?
 
For that matter, why should we model the earth after a round ball when we know it fits better on a table top?

Seriously, you're going to have to account for declination somehow. If your database is out if date, or god forbid you have to do it manually, you might start sweating some bullets.
 
NoHeat said:
With GPS navigation so common and cheap now, why do we still number our runways according to their magnetic direction? And the direction of our VOR radials and airways? And our headings on approach charts?

It's just a nuisance and an expense to keep updating these.

If aviation switched from magnetic to true, the few aviators who still navigate solely by magnetic compass (and gyros that are set by magnetic compass) would have to make adjustment for declination. As it is right now, everybody else, from pilots to chart makers to VOR technicians to runway painters must make the adjustment. And at a considerable cost that is never ending.

Just think of the ease and economy that would be gained by leaving everything numbered true, and leaving it that way.

So wouldn't it be cheaper and easier for most of the world of aviation to just switch?
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If you have a GPS onboard, you likely don't even need to use the headings for airways, runways, and headings... you just plug it into the GPS.
 
Because nobody has yet come up with a device which, without power, aligns itself to true north.
 
Ron Levy said:
Because nobody has yet come up with a device which, without power, aligns itself to true north.
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Hasn't stopped the maritime world from using True North.

I have always been under he impression that the bigger issue is that aviation gyros precess a lot more than larger ship gyros (I have never had to adjust a ship gyro for precession) and at the speeds that airplanes travel, you will cross isogenic lines much more frequently, making compass corrections more challenging when periodically adjusting for precession.

MUCH easier to simply go straight off the magnetic compass and not have to worry about factoring in he variation.
 
Not to mention... GPS can figure out magnetic north just fine.
 
Ron Levy said:
Because nobody has yet come up with a device which, without power, aligns itself to true north.
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Sure, but if the aviator must navigate without power, he can still add and subtract small numbers, right? All that he needs to know is the declination, plus or minus a degree, which isn't hard, unless you're near the magnetic pole.

Somebody has to adjust for declination. I propose that it be the aviator flying by compass, and not the rest of the world.
 
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Fearless Tower said:
Hasn't stopped the maritime world from using True North.

I have always been under he impression that the bigger issue is that aviation gyros precess a lot more than larger ship gyros (I have never had to adjust a ship gyro for precession) and at the speeds that airplanes travel, you will cross isogenic lines much more frequently, making compass corrections more challenging when periodically adjusting for precession.

MUCH easier to simply go straight off the magnetic compass and not have to worry about factoring in he variation.
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Sperry gyrocompass are (true) north-seeking. That's how they can work on submarines.
 
Ron Levy said:
Because nobody has yet come up with a device which, without power, aligns itself to true north.
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That's a consideration. Probably not the real reason. I'd guess recalibrating about a thousand VOR stations and repainting about a thousand runways and making a huge change to the pilot's curriculum are the real reasons.
 
Old Geek said:
That's a consideration. Probably not the real reason. I'd guess recalibrating about a thousand VOR stations and repainting about a thousand runways and making a huge change to the pilot's curriculum are the real reasons.
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Exactly. The technology exists today where the need for adjusting/correcting for constantly preceding gyros, but after over a century of navigating by magnetic North, the expense of shifting is just not worth it.
 
Sac Arrow said:
For that matter, why should we model the earth after a round ball when we know it fits better on a table top?

Seriously, you're going to have to account for declination somehow. If your database is out if date, or god forbid you have to do it manually, you might start sweating some bullets.
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Plus it would be so expensive to move runways a few degrees right or left. :)
 
NoHeat said:
With GPS navigation so common and cheap now, why do we still number our runways according to their magnetic direction? And the direction of our VOR radials and airways? And our headings on approach charts?

It's just a nuisance and an expense to keep updating these.

If aviation switched from magnetic to true, the few aviators who still navigate solely by magnetic compass (and gyros that are set by magnetic compass) would have to make adjustment for declination. As it is right now, everybody else, from pilots to chart makers to VOR technicians to runway painters must make the adjustment. And at a considerable cost that is never ending.

Just think of the ease and economy that would be gained by leaving everything numbered true, and leaving it that way.

So wouldn't it be cheaper and easier for most of the world of aviation to just switch?
Click to expand...

I don't understand the difficulty. If you're navigating by GPS, why on earth do you even care? Punch in your plan, fly it, don't look at the compass. When you're on final approach, look at the runway numbers and not the GPS.

Helluva lot easier than repainting all the runways, realigning all the VOR's, republishing all the charts, re-flight-checking all the approaches, etc. etc.

IOW, it really doesn't matter. It's a standard. Use it and you'll be fine.
 
Because the GPS has a MAG/TRUE button and the compass doesn't. So if everything were to be referenced to True North the magnetic compass would be useless.
 
Silvaire said:
Because the GPS has a MAG/TRUE button and the compass doesn't. So if everything were to be referenced to True North the magnetic compass would be useless.
Click to expand...

Which is exactly the point of this thread..;)
 
NoHeat said:
Sure, but if the aviator must navigate without power, he can still add and subtract small numbers, right? All that he needs to know is the declination, plus or minus a degree, which isn't hard, unless you're near the magnetic pole.
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It's actually variation, not declination with which you'd be adjusting, and you'd have to start with mag and then convert, which essentially defeats the purpose of the exercise.
 
Ron Levy said:
It's actually variation, not declination with which you'd be adjusting, and you'd have to start with mag and then convert, which essentially defeats the purpose of the exercise.
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Agreed.. Declination is a very small correction based on latitude. The Op's point is any GPS can convert mag to true easiely.. For the die hard, old school pilots they can stil use a mag compass and do the correction for variation in their head...
 
Someone had too. If you fly low nuff just look to see which side of the trees has moss on them.
 
N801BH said:
Agreed.. Declination is a very small correction based on latitude. The Op's point is any GPS can convert mag to true easiely.. For the die hard, old school pilots they can stil use a mag compass and do the correction for variation in their head...
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Doesn't help if you don't know where you are close enough to know what variation to apply, doesn't help if you don't have a GPS, and doesn't address my original question -- you're going to be basing it on a mag compass, so why complicate it further with mental corrections? Build something that senses true heading without any power, and maybe there's a path to that. Otherwise, it's not worth discussing further.
 
Ron Levy said:
Doesn't help if you don't know where you are close enough to know what variation to apply, doesn't help if you don't have a GPS, and doesn't address my original question -- you're going to be basing it on a mag compass, so why complicate it further with mental corrections? Build something that senses true heading without any power, and maybe there's a path to that. Otherwise, it's not worth discussing further.
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:rolleyes:
 
flyingcheesehead said:
I don't understand the difficulty. If you're navigating by GPS, why on earth do you even care? Punch in your plan, fly it, don't look at the compass. When you're on final approach, look at the runway numbers and not the GPS.
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You've missed my point. Which is my fault for not being clear.

Very little of my concern is the pilot, although that is understandably the focus of your post since you are a pilot. Sure, the pilot can manage with either system.

My concern was mostly all the other stuff -- the cost of constantly changing all the VOR radials, runway numbers, airway headings, approach chart headings, and so on. It is a significant cost, so much so that because of the cost VOR radials are not adjusted often enough in response to changes in the Earth's field.

The Earth's magnetic field is constantly changing. That's what this is all about. So we have to constantly be busy, and spending money, adjusting fixed things like runway orientations as the field changes. It would be so much easier and cheaper to leave these fixed things alone, and that can be done simply by referencing them to true north which is also fixed.
 
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Ron Levy said:
you'd have to start with mag and then convert, which essentially defeats the purpose of the exercise.
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Who would have to?

If we had a system of navigation that is entirely based on true north, almost nobody would have to convert anything. The only pilots who would need to do so are (1) those who normally don't use GPS, and (2) those who have a failure of their GPS or electrical system. These two kinds of pilots can still navigate using a true-north navigation protocol - they can do so using their magnetic compass, or heading indicator that is set by magnetic compass. To do so, they would just have to add or subtract a small number.

It would be so much better to slightly inconvenience those few than to cause a great cost by so many. The latter is our current system.
 
NoHeat said:
With GPS navigation so common and cheap now, why do we still number our runways according to their magnetic direction? And the direction of our VOR radials and airways? And our headings on approach charts?

It's just a nuisance and an expense to keep updating these.

If aviation switched from magnetic to true, the few aviators who still navigate solely by magnetic compass (and gyros that are set by magnetic compass) would have to make adjustment for declination. As it is right now, everybody else, from pilots to chart makers to VOR technicians to runway painters must make the adjustment. And at a considerable cost that is never ending.

Just think of the ease and economy that would be gained by leaving everything numbered true, and leaving it that way.

So wouldn't it be cheaper and easier for most of the world of aviation to just switch?
Click to expand...


Worldwide, you would have to re-number all the runways, re-align all the VORs, test and re-publish all the instrument approaches, re-align all the automated weather stations, ..... Not much economy in all that.
 
Clip4 said:
Worldwide, you would have to re-number all the runways, re-align all the VORs, test and re-publish all the instrument approaches, re-align all the automated weather stations, ..... Not much economy in all that.
Click to expand...

That's not clear.

You only have to do it once. You have to re-align the VOR's and renumber the runways every time the magnetic variation changes a couple of degrees. Change everything to true and you'll never have to do it again.
 
Ron Levy said:
Build something that senses true heading without any power, and maybe there's a path to that. Otherwise, it's not worth discussing further.
Click to expand...

Disagree. Edit: well maybe disagree is a bit strong, but I think that even if you had something that sensed True North without power, it wouldn't be worth changing.

As I pointed out earlier, power isn't really the issue. We have been navigating with True North on ship gyros since they were invented with a magnetic compass as the backup. If you lose the gyro, you go magnetic and do the old CDMVT+E routine.

But aviation started with magnetic from the get-go. Largely because in the beginning there were no gyros in airplanes and it is much more challenging to do compass corrections in the air. When airplanes first got gyros, the were small and had to be constantly adjusted in flight off the whiskey compass. Since straight magnetic was the easiest to use, it only made sense that the entire infrastructure from radio navigation to runway designation was based off of magnetic. That system has been used for over 100 years. The cost benefit to change now simply does not support it.
 
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Clip4 said:
Worldwide, you would have to re-number all the runways, re-align all the VORs, test and re-publish all the instrument approaches, re-align all the automated weather stations, ..... Not much economy in all that.
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But you're having to do all that frequently already, due to the constantly changing direction of Earth's magnetic field. That is my point.

Make the changes just once, to true north, and leave them that way forever instead of constantly changing over and over. That's where the economy would be.

Edit, I see that Old Geek said the same thing already.
 
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Start with the easy stuff. Get rid of all the weird weather notations. There is no reason on earth Metams and all the other weather info can't be posted in plain English.
 
Nobody gets into a no-electrcal-system aircraft and hauls off on a long xc to somewhere they've never been before anymore using only a whisky compass and vfr sectionals. They've at least got a handheld GPS or at minimum a gps-equipped smartphone or tablet. Well, maybe if they're trying to do something "nostalgic" (read that as "freakin' retarded").
 
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NoHeat said:
You've missed my point. Which is my fault for not being clear.

Very little of my concern is the pilot, although that is understandably the focus of your post since you are a pilot. Sure, the pilot can manage with either system.

My concern was mostly all the other stuff -- the cost of constantly changing all the VOR radials, runway numbers, airway headings, approach chart headings, and so on. It is a significant cost, so much so that because of the cost VOR radials are not adjusted often enough in response to changes in the Earth's field.

The Earth's magnetic field is constantly changing. That's what this is all about. So we have to constantly be busy, and spending money, adjusting fixed things like runway orientations as the field changes. It would be so much easier and cheaper to leave these fixed things alone, and that can be done simply by referencing them to true north which is also fixed.
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I see...

Well, you'd have to repaint runways every so often anyway, so probably no real savings there. You might even have to adjust VOR's periodically anyway, though someone with more knowledge of how they work would have to answer that for sure. So you might not save much there either.

But if you were to switch from Magnetic to True for runways and VORs, you'd either have to do it all at once ($$$$$$$$) or if you just waited for when the next adjustment would have been, we'd all be trying to figure out for the next 20 years or so whether the field we were approaching was in Mag or True. Blech!

If it had started as true, great. Since we're on Magnetic already, I think the cost to switch far outweighs the small long-term advantage you might gain from doing so.
 
NoHeat said:
My concern was mostly all the other stuff -- the cost of constantly changing all the VOR radials, runway numbers, airway headings, approach chart headings, and so on. It is a significant cost, so much so that because of the cost VOR radials are not adjusted often enough in response to changes in the Earth's field...
Click to expand...

Really? I've been flying for 45 years and honestly I can't name an airport where they have changed the runway numbers. Maybe some of them have but "constantly"? I think you're making a big issue out of nothing.

Besides, if you're worried about cost wouldn't it cost a lot to have to change every single one of them over night? :dunno:
 
Silvaire said:
Really? I've been flying for 45 years and honestly I can't name an airport where they have changed the runway numbers. Maybe some of them have but "constantly"? I think you're making a big issue out of nothing.

Besides, if you're worried about cost wouldn't it cost a lot to have to change every single one of them over night? :dunno:
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Hmmmm..

All it takes is 10 gallons of white paint.....

This administration calls that a "shovel ready" project...:rofl:..

Can you say Stimulas project...:dunno:...:lol:
 
Silvaire said:
Really? I've been flying for 45 years and honestly I can't name an airport where they have changed the runway numbers. Maybe some of them have but "constantly"? I think you're making a big issue out of nothing.

Besides, if you're worried about cost wouldn't it cost a lot to have to change every single one of them over night? :dunno:
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I've seen one and I think my home airport is just a few years from needing to be changed. Annual shift at least around here is 0.1deg and our runways are 174 and 354. I don't remember the 10ths, though.

After reading this article, it may be a while longer. They're allowed 5 degrees difference
http://www.mercurynews.com/breaking...etic-shift-causes-first-change-runway-numbers
 
Neal Howard said:
Nobody gets into a no-electrcal-system aircraft and hauls off on a long xc to somewhere they've never been before anymore using only a whisky compass and vfr sectionals. They've at least got a handheld GPS or at minimum a gps-equipped smartphone or tablet. Well, maybe if they're trying to do something "nostalgic" (read that as "freakin' retarded").
Click to expand...

When those things run out of battery, lose signal, or plain fail (it happens), then you're going to wish you could function so retarded.
 
Runways are magnetic and the ground winds are true right? That one could be made consistent. Make runways true would be a start.
 
I think Barry Schiff wrote a column on this topic in "Pilot". Benefits of changing to True North was his pitch, too
 
Neal Howard said:
Nobody gets into a no-electrcal-system aircraft and hauls off on a long xc to somewhere they've never been before anymore using only a whisky compass and vfr sectionals. They've at least got a handheld GPS or at minimum a gps-equipped smartphone or tablet. Well, maybe if they're trying to do something "nostalgic" (read that as "freakin' retarded").
Click to expand...
If you can't do precisely that you're not qualified to hold a pilots licence, IMO.
 
Runway numbers are rounded, so they change only 1/10 as often as the charts and navigation databases.
 
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