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Earth Transportation Science

Magnetic Pole Shift Affects Tampa Airport 317

RFSSystems writes "I thought this was an amazing and rather rare phenomenon and wanted to share. 'The airport has closed its primary runway until Jan. 13 to repaint the numeric designators at each end and change taxiway signage to account for the shift in location of the Earth's magnetic north pole.' It appears that the shifting poles have begun to affect air travel in a somewhat modest way. Could this also be the explanation for the falling/dead birds this week?" I hope the gradualists are right, but scenarios for rapid magnetic pole shift are fun to think about.
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Magnetic Pole Shift Affects Tampa Airport

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  • Happens all the time (Score:5, Informative)

    by Anonymous Coward on Thursday January 06, 2011 @03:47PM (#34781394)

    The airport I work at has a second set of signage from when the gradual shift occurs in cycles, making for a 10 degree change in the direction of the runway. Ie, here it will be runway 10-28 becoming runway 09-27. Has nothing to do with birds, happens every decade or so. Ten years after that, itll be back to what it is now.

  • Not rare at all (Score:5, Informative)

    by Urban Garlic ( 447282 ) on Thursday January 06, 2011 @03:48PM (#34781400)

    Changing magnetic deviation due to movement of the magnetic pole goes on all the time. Runways are numbered according to their magnetic heading, plus or minus five degrees, and they have to keep them up to date, is all.

    Two seconds of googling found this comment thread [] discussing a different runway-renumbering from July of 2009.

    Obviously not enough airplane geeks around here...

  • by Xocet_00 ( 635069 ) on Thursday January 06, 2011 @03:49PM (#34781426)
    The movements of magnetic north have, on many prior occasions, caused airports to have to redesignate their runways. Since it requires updating of all the charts that aircraft are required to carry (not to mention signage on the ground), it's often deferred as long as possible. Tampa doing this isn't really that significant, although I admit that it's kind of neat in a visual-manifestation-of-invisible-phenomenon kind of way.

    Wikipedia subsection on the subject. []
  • by ASimPerson ( 138798 ) <asim.asimweb@org> on Thursday January 06, 2011 @03:52PM (#34781464) Journal
    This has happened before, and it'll happen again.

    Airport runway numbers are based off their magnetic headings with the last zero removed. So a runway that runs due south/north is 18/36 (i.e., it faces 180 degrees south and 360 degrees north - 0 isn't used). A runway that runs due east/west is 9/27. And so on. When there are parallel runways facing the same direction, the L, C, and R designations are used. A pair for parallel east/west runways are 9R/27L and 9L/27R.

    So as the pole drifts this sometimes causes runways to have be renumbered. One previous example is Reagan-National airport [] in Washington, D.C., where runways 1/19 and 4/22 were originally 18/36 and 3/21.
  • by Elder Entropist ( 788485 ) on Thursday January 06, 2011 @03:52PM (#34781466)
    Your "rapid magnetic pole shift" link is to an article about the (fairly ridiculous) rapid shift of the axis of rotation of the planet rather than the magnetic pole. The two really should not be confused.
  • by $RANDOMLUSER ( 804576 ) on Thursday January 06, 2011 @04:05PM (#34781664)
    Here's [] a really cool animated gif from Wikipedia, showing the magnetic declination [] changing over time.
  • by Orion2 ( 200288 ) <{hc.ylimafiluap} {ta} {oter}> on Thursday January 06, 2011 @04:20PM (#34781912)

    Changes to stuff like this are introduced on a cycle once every 28 days - called an "AIRAC cycle". The AIRAC is synchronized all over the world, so all the systems, charts and the like on the ground and in aircraft can be updated accordingly. Obviously there is some lead time ahead to allow for publication, distribution and update of the information and depending systems.

    Imagine if it was only once a year - every change affecting more than one airspace user or aviation service provider in the world would have to be introduced together. This would in consequence mean that you could only open a new runway, introduce a departure procedure or many more things on that date.

    On top of this there's a notification scheme for distributing info like non-functioning equipment, temporarily closed runways (for which you don't change maps forth and back), procedures to adhere, info about an airshow and the like. This is called a NOTAM - short for NOtice To AirMen.

  • by kaleth ( 66639 ) on Thursday January 06, 2011 @04:27PM (#34781988)

    Because not every plane has a GPS or INS. (Certified) GPS equipment is still new and expensive for airplanes. INS is very large and heavy, and only used on large commercial jets.

    And perhaps most importantly, a compass always works. If everything else fails, you still have that as a backup.

  • by Martin Blank ( 154261 ) on Thursday January 06, 2011 @04:43PM (#34782280) Homepage Journal

    The compass requires no electrical power.

    I fly a Cessna 172S equipped with a Garmin G1000. It's a glass cockpit that makes life much, much easier, but I still have a few analog instruments: compass, attitude indicator, airspeed indicator, and altimeter. All of them function on principles in place on aircraft for many decades now, and provide a layer of reliability in case just about everything goes wrong. I can lose the entire electrical system and still be able to fly to the best landing site available, because the compass is based on the Earth's magnetic field, the attitude indicator is based on a vacuum-driven gyro (the vacuum pump is mechanical and run by the engine), the altimeter is based on the static air pressure, and the airspeed indicator is based on both the pitot tube and the static air pressure. (The engine spark is provided by magnetos that will keep providing spark as long as the engine is turning - no battery required.)

    There are complications when flying at night, but that's why I carry a hand-held navcom radio and a couple of flashlights with me in my flight bag.

  • by spaceyhackerlady ( 462530 ) on Thursday January 06, 2011 @05:03PM (#34782640)

    Because they offer the best bang for the buck. Because pilots are trained to use them. Because they work. Because aviation is totally anal about "if it ain't broke, don't fix it". This is A Good Thing.

    I'm learning to fly in Piper Cherokees, and I have a magnetic compass and gyroscopic heading indicator at my disposal. Both are accurate, but both have idiosyncrasies.

    The magnetic compass is subject to errors when accelerating or decelerating on east/west courses. It also misbehaves when turning to/from north or south. The heading indicator slowly drifts as Earth rotates underneath it. On long flights you have to periodically re-set the heading indicator.

    The pre-takeoff checklist includes setting the heading indicator to the magnetic compass, and verifying that both read correctly when you pull on to the runway. In the future Runway 01 (13 degrees) will become Runway 36 or Runway 02.


  • Re:Not rare at all (Score:4, Informative)

    by digitig ( 1056110 ) on Thursday January 06, 2011 @05:29PM (#34783012)

    Runways are numbered according to their magnetic heading, plus or minus five degrees

    Plus an alphabetic suffix such as "L" or "R" in the case of parallel runways.

  • by trollertron3000 ( 1940942 ) on Thursday January 06, 2011 @05:56PM (#34783436)

    Yup. The compass is one of the few instruments required in every aircraft in the US. Give me a tachometer, a compass, and an altimeter and I can navigate an airplane across the US.

    GPS just recently came into the cockpit and the devices are expensive. People should realize that these are aviation instruments, so they need to be certified and are in turn expensive.

    INS isn't in every aircraft simply because not every aircraft needs to be instrument-rated. Some people, like myself currently, only fly in VFR conditions. Removing these expensive instruments saves money, as you said.

    Want to see a pilot bitch? Tell him he needs to buy something. For a great example of this search Google for the term "ADB-S requirement" and see the pilots moan about this new requirement. I should know, I'm one of them :D

  • by rjstanford ( 69735 ) on Thursday January 06, 2011 @06:02PM (#34783508) Homepage Journal

    Huh, I have a military fighter aircraft grade INS with a 2 hour battery backup packed into a 3U rackmount box right next to me that indicates it weighs 17lbs. Yea, it was expensive (low 5-figures). So are aircraft.

    Many aircraft cost in the mid-to-high 5-figures. Adding 10-20% to a private plane's cost, or double that if you want redundancy, seems excessive when the only benefit is some geek's sense of correctness. Adding 6U worth of rack equipment isn't exactly easy either - space can be quite tight up there as it is.

  • by BobMcD ( 601576 ) on Thursday January 06, 2011 @07:17PM (#34784486)

    Note that this is only true from the human's perspective. From the Earth's, it has actually traveled all the way to the other side and back, many times over.

  • Re:True North (Score:3, Informative)

    by Russ1642 ( 1087959 ) on Thursday January 06, 2011 @07:43PM (#34784800)
    You only do that way, way up north where compasses aren't reliable. The runways in Canada use magnetic numbers just like everyplace else. At the Edmonton City Centre airport there's a pub located at the end of runway 30. The pub is named Runway 29, but they didn't want to change their name when the magnetic pole moved and the runway was renumbered.
  • Re:I wonder (Score:4, Informative)

    by Chyeld ( 713439 ) <chyeld&gmail,com> on Thursday January 06, 2011 @08:08PM (#34785088) []

    They say it better than I could:

    One thing to remember is what day and time the incident occurred: near midnight on New Year's Eve. Plenty of people mark the beginning of the new year with fireworks, and it's possible these celebrations caused this nasty accident. Arkansas Game and Fish Commission spokesman Keith Stephens says the commission currently favors this theory, as fireworks that were shot off in just the right area near the birds when they were roosting could have scared them, creating a traumatic stress event.

    Why are thousands of dead birds suddenly falling from the sky?

    Obviously, birds don't usually fall from the sky when fireworks are shot off, so what would have happened here? We do know that birds tend to be more highly concentrated in rural areas, meaning one big fireworks blast in just the wrong area would have terrified thousands of birds all at once.

    This would have happened at night, when birds are roosting on the ground - and if this did indeed happen when the birds were asleep, experts say the trauma would have been enough to kill them, as the terrified birds frantically flew into each other in the heavy night fog. Witnesses have since come forward to say they saw a person setting off industrial-grade fireworks near the roosting area, which would seem to back up that theory.

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