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.
Happens all the time (Score:5, Informative)
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)
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 [airliners.net] discussing a different runway-renumbering from July of 2009.
Obviously not enough airplane geeks around here...
Difficult to change, but not that rare. (Score:5, Informative)
Wikipedia subsection on the subject. [wikipedia.org]
Actually somewhat common (Score:5, Informative)
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 [wikimedia.org] in Washington, D.C., where runways 1/19 and 4/22 were originally 18/36 and 3/21.
Magnetic/Spin Axis Confusion (Score:5, Informative)
Re:Difficult to change, but not that rare. (Score:5, Informative)
Re:Difficult to change, but not that rare. (Score:5, Informative)
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.
Re:For the airplane geeks... (Score:4, Informative)
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.
Re:For the airplane geeks... (Score:5, Informative)
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.
Re:For the airplane geeks... (Score:5, Informative)
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.
...laura
Re:Not rare at all (Score:4, Informative)
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.
Re:For the airplane geeks... (Score:5, Informative)
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
Re:For the airplane geeks... (Score:4, Informative)
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.
Re:Happens all the time (Score:4, Informative)
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)
Re:I wonder (Score:4, Informative)
http://io9.com/5725175/why-are-thousands-of-dead-birds-suddenly-falling-from-the-sky [io9.com]
They say it better than I could: