Earth’s magnetic pole shifts, screws up runway at Florida airport

The Lookout | Liz Goodwin

[equaviator]

An airport in Tampa, Florida, has had to temporarily close its runways to keep up with Earth's magnetic north pole, which is drifting toward Russia at a rate of 40 miles per year.

Fox News reports that the international airport was forced to adjust the signs on its busiest runway Thursday because pilots depend on the magnetic fields to navigate. The runway will be closed until Jan. 13, and will re-open with new taxiway signs that indicate its new location on aviation charts, the Tampa Bay Tribune reports.

Paul Takemoto, a spokesman for the FAA, says the Earth's magnetic fields are constantly in flux -- but rarely so much so that runway signage needs to be changed. "You want to be absolutely precise in your compass heading," he told Fox. "To make sure the precision is there that we need, you have to make these changes."

"The Earth's poles are changing constantly, and when they change more than three degrees, that can affect runway numbering," FAA spokesperson Kathleen Bergen told Fox News. It's unclear whether any other airports will have to adjust their runways.

Earth's magnetic field, which still flummoxes those who study it, "is thought to be generated deep inside the planet," LiveScience writer Jeanna Bryner explains. "An inner core of solid iron is surrounded by an outer core of molten iron. They rotate at different rates, and the interaction between the regions creates what scientists call a 'hydromagnetic dynamo.' It's something like an electric motor, and it generates a magnetic field akin to a giant bar magnet."

Sometimes, the poles completely flip -- and presumably when that happens, many bigger changes are afoot than modest tweaks to airport signs. The last time the planet experienced a polarity flip was 780,000 years ago.

[BwanaNdege]

The airport has not moved. Only the direction in which the compass points has shifted since the runways were first laid out in 1928.

Compass heading at most airports is constantly changing by varying amounts. Whether or not runways need to be re-designated/renamed depends on how fast magnetic declination changes at that location and how long it has been since the runway was laid out.

Also, if the runway was originally laid out exactly at 180 degrees they would name it “Runway 18”, the nearest 10 degree increment. Since the magnetic declination at tampa has shifted over 7 degrees since Drew Field was first opened, the current heading would be 187, or “Runway 19”. This would hold true for original directions of 179 to 184 and everything in between.

[InternetTuffGuy]

How would anyone be able to state, as a fact, that the planet experienced a polarity flip 780,000 years ago?

Test it yourself. Take molten rock. Cool it. Now see which direction that newly solidified rock's magnetic orientation is.

If you live next to, say, a volcano, or a mid ocean ridge, you can harvest core samples and see which way the magnetic fields are aligned.

Geology isn't rocket science, but it rocks!

[ClearBlueSky]

The North Pole is moving? Does Santa need help? How much does it cost to move an entire pole anyway? Do the environmentalists approve? Was it our hairspray?-lol
Might be affecting the birds and other animals tho!

[CodeToad]

Reporters are the dumbest people. The runway was not closed because of magnetic deviation.

[BwanaNdege]

The airport has not moved. Only the direction in which the compass points has shifted since the runways were first laid out in 1928.

Compass heading at most airports is constantly changing by varying amounts. Whether or not runways need to be re-designated/renamed depends on how fast magnetic declination changes at that location and how long it has been since the runway was laid out.

Also, if the runway was originally laid out at anything from 175 to 184 degrees they would have named it “Runway 18”, the nearest 10 degree increment. Since the magnetic declination at Tampa has shifted over 7 degrees since Drew Field was first opened, the current heading would be between 182 and 191. A current heading of 185 and above would be called “Runway 19”.

[BenKenobi]

I’d imagine Florida would have the largest magnetic declination?

[GatorGirl]

Good point. That airport is on the water and planes are pretty heavy! ;-)

[anniegetyourgun]

I would so like to buy this theory - because it means man didn’t influence it & can do nothing about it!

[Gondring]

How would anyone be able to state, as a fact, that the planet experienced a polarity flip 780,000 years ago?

The classic way is the examination of the sea floor basalts as they are created at mid-ocean ridges, where the sea-floor spreads and new rock is formed at the ridge. When it cools, it locks into place the magnetic orientation. The rock age is determined by principles similar to those used in carbon-dating, atomic clocks, and medical devices.

Sedimentary particles can be used in areas away from magnetic ridges, allowing for determination of tectonic plate movements.

Is this the same crew that is telling us about global warming, when I look out my window, and see 6-7 inches of snow, single digit temps, and it's been exceptionally cold since early November.

I guess that's sorta the next step from seeing Russia from there, huh? You claim you can see the entire globe?

I hear there was a warming trend in Australia over that same time period.

Or maybe you missed the word "global." You wouldn't be alone--many FReepers do.

[epithermal]

Actually one of the areas with the least declination:

[epithermal]

How am I going to set my compass during a reversal?:

[Gondring]

Actually, as you go farther north and east, you'll have the greatest separation between true north and magnetic north. In the midwest US, both are in about the same direction, it's just that the magnetic pole is closer. Then, in the western US, the farther to the northwest you go, the greater the separation between the two.

In this figure, the red arrow is toward the magnetic pole and the black one is toward true north. Note how the difference between arrows is greater the farther north you go, as well as the farther east or west you are from the magnetic north pole:

That gives us a map like this:

Of course, in Canada, it gets really funky, since you can be in an area where the you can be north of the magnetic pole, but south of the true pole...such as if you were up above the star (magnetic pole) on this figure:

[Gondring]

How am I going to set my compass during a reversal?:

Decline before you flip out!

[M Kehoe]

27R-9L no more.

5.56mm

[Gondring]

So, let me get this straight. ONE airport in Florida is affected by this? And the rest of the world has adjusted? Or is perhaps not affected? Doesn’t make sense scientifically to me.

This happens all over, but it ran as a news story and has now been posted on FR a few times in the past few days. (The runway numbers are "rounded off" so it's rare for the actual runway change, though.)

[BwanaNdege]

"I’d imagine Florida would have the largest magnetic declination?"

Actually, much of Florida is close to zero. The largest declinations are in the northern states, especially the far NW & NE.

Here is a neat website to find your magnetic declination.

"http://www.magnetic-declination.com/"

[Gondring]

Nice site--thanks!

Cute little graphic of historical pole wanderings:

[Professional Engineer]

Of all the runways, at all of the airports, all over the world... the magnetic shift has resulted in re-designation of just this one?

THis is because every other runway on the planet was installed on vertical pivots to keep up with magnetic drift. Why do you think airports are so large geographically? So the runways can swing about freely.

[P.O.E.]

"That's the second biggest magnet I've ever seen"

[equaviator]

So, would the alleged declination affect GPS satellite accuracy or not?

I understand runway designations per their respective alignments. Here in SE MI, the main runway at Selfridge Air Natinal Guard Base is designated as being “19” and is physically marked as such.

All I have to do is run the X-Plane flight simulator, go to that location and sure enough, the cockpit compass’s heading reading matches to the nearest degree (at the most) as the aircraft is positioned for takeoff.