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Magnetic change?

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Magnetic change?

Old 11th Jan 2019, 21:49
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Magnetic change?

Just found this.
Apparently its changing faster.
What to expect?
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Old 11th Jan 2019, 21:54
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Originally Posted by testpanel View Post
What to expect?
Someone will figure out a way to tax it...
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Old 11th Jan 2019, 22:19
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Someone will figure out a way to tax it...
Wasn't that Edison?
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Old 12th Jan 2019, 06:48
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Polarity switch on its way? Not due...but..
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Old 12th Jan 2019, 07:28
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If there is a polarity shift, does it become West Anglia?
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Old 12th Jan 2019, 07:28
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Originally Posted by Herod View Post
Polarity switch on its way? Not due...but..
its overdue isn’t it?
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Old 12th Jan 2019, 08:41
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Some runways will need to be renumbered but VORs will not change and will be confusing.
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Old 12th Jan 2019, 08:47
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This reminds me of a route we flew years ago, overflying Sudan, east/west.. Somewhere between 100 and 200nm west of Khartoum, the standby compass (float type) would give a pronounced dip, in the direction expected, for a duration of about 5mins. IIRC.

All sorts of theories of course amongst the crew(s). but nothing convincing for me, except it had to have been external influence.
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Old 12th Jan 2019, 08:53
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Originally Posted by The Ancient Geek View Post
Some runways will need to be renumbered but VORs will not change and will be confusing.
What makes you think VOR radials won't change?
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Old 12th Jan 2019, 09:08
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The orientation of VOR antennas is fixed at the time of installation and cannot be changed so the radials refer to the magnetic north which existed when installed.
Note that this refers to the LOCAL magnetic field which may or may not be significantly changed by the magnetic pole wandering as described in the article.
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Old 12th Jan 2019, 09:37
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Originally Posted by The Ancient Geek View Post
The orientation of VOR antennas is fixed at the time of installation and cannot be changed so the radials refer to the magnetic north which existed when installed.
Note that this refers to the LOCAL magnetic field which may or may not be significantly changed by the magnetic pole wandering as described in the article.
I don't think that's correct. Here's an example of VOR radials that have changed in line with shifted magnetic declination:


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Old 12th Jan 2019, 09:48
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Scientists are not just talking about an increasing Variation Drift. Talk is of a sudden 180 deg shift.
It has happened in the past.
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Old 12th Jan 2019, 09:56
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Why don't we switch to true north navigation, just publish all as true, zero all variation databases in the IRS an be done with it!
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Old 12th Jan 2019, 09:58
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Originally Posted by KiloB View Post
Scientists are not just talking about an increasing Variation Drift. Talk is of a sudden 180 deg shift.
It has happened in the past.
It has? When?
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Old 12th Jan 2019, 10:03
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Originally Posted by Capt Fathom View Post
It has? When?
Most recently, about 780,000 years ago.

I don't think that one caused any problem for pilots.

Brunhes–Matuyama reversal
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Old 12th Jan 2019, 10:08
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Short term - change in compass declination, repainting work etc

medium term - gradual decline in field strength and more variability

long term - flip - but that may take 500 years - nothing to much to worry about - its happened lots of times since Homo sap. started
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Old 12th Jan 2019, 10:52
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The orientation of VOR antennas is fixed at the time of installation and cannot be changed so the radials refer to the magnetic north which existed when installed.
Note that this refers to the LOCAL magnetic field which may or may not be significantly changed by the magnetic pole wandering as described in the article.
Not the case. All VORs can be adjusted. More modern versions with just the tweak of a screwdriver or the press of a few keys on a laptop, older ones sometimes required large spanners and a hammer. The practice in the UK and most states is to adjust them during flight inspection to minimise the predicted difference over the period to the next expected flight inspection. For DVOR that is 5 years in the UK.
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Old 12th Jan 2019, 11:21
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North and South is a Geographical term, referring to the two poles of the earth's rotational axis. In layman's terms, the North is to the left when facing in the direction of the Earth's rotation, and South is to the right. The magnetic poles have simply been named in their relation to the geographical poles. Should the polarity reverse all that needs to be changed is the naming convention, from that moment onwards the former magnetic South becomes North and vica versa, and everything is back to normal.
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Old 12th Jan 2019, 11:42
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A pole reversal, or a N/S polarity change, takes a few centuries to stabilize. That is pretty confusing I reckon.
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Old 12th Jan 2019, 11:49
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Avionics-wise we should be able to switch to true north by now but wasn't there something about the magnetic field weakening in conjunction with a flip, thus removing the protection against space radiation for some time....
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