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On 01/14/2011 05:52 AM, Anthony Lapinski wrote:
http://news.yahoo.com/s/yblog_thelookout/20110107/sc_yblog_thelookout/florida-temporarily-closes-runway-due-to-magnetic-pole-shifting&vm=r
Saw this article online. Tampa airport had to close because Earth's
magnetic pole is shifting.
Or, to say the same thing more precisely, the article *claims*
that Fox News *claims* that's why the airport was closed.
Never knew of airports closing because of this.
You've never heard of it because it has never happened. No
airport has ever closed «because» of the earth's changing
magnetic field.
Has this happen at other airports?
No. It didn't happen at Tampa, either.
===========================
The article traces the chain of "causation" one step further back. It
says «... because pilots depend on the magnetic fields to navigate.»
It also says Fox says the FAA says «You want to be absolutely precise
in your compass heading». Similarly «when they change more than three
degrees, that can affect runway numbering».
All of that is compleat hogwash.
Here are some actual factual facts:
-- At Tucson, runways 11L/29R and 11R/29L are 13 degrees off their
nominal heading. It has been that way for several decades, and
there are no plans to change it.
http://airnav.com/airport/KTUS
-- At Los Angles, runways 6L/24R and 6R/24L are 9 degrees off their
nominal headings. Again, it has been that way since forever, and
there are no plans to change it.
http://airnav.com/airport/KLAX
Oh, and how about the obvious fact that since runway names are quantized
to the nearest 10 degrees, if the orientations are randomly distributed
you expect 40% of them to be off by more than 3 degrees, even if the
roundoff is up-to-date and mathematically exact.
And then there's the fact that when approaching the runway, it would not
be surprising (just annoying) to find your /heading/ differs from your
/course/ by more than 15 degrees, due to crosswinds.
If I were trying to land on runway 9 and the heading was 180 I might
conclude I was looking at the wrong runway, and maybe even the wrong
airport ... but that's not what the article is talking about, and that
does not require being «absolutely precise» nor even having «3 degrees»
of precision. Not even close.
It's true that pilots check the calibration of their compass by comparing
it to the runway heading ... but they compare it to the published runway
heading (not to the runway name multiplied by ten). Changing the published
runway heading does not require closing the airport. They just change the
publications every so often. The deltas between publications are so small
that there is no disruption. None whatsoever.
All in all, nobody cares very much about runway numbering.
The situation is somewhat trickier with regard to the VORs, which are
enroute navigational aids, and which are supposed to be aligned with
the local magnetic field. The FAA by its own rules is supposed to
re-align them every few years, but they are many many years behind
schedule, and some of the VORs are significantly out of whack. Few
people noticed this, and even fewer cared, until GPS came along and
gave pilots something to check the VOR system against. This is ten
times more of an issue than runway numbering, and even so it barely
rises to the level of an occasional annoyance. It is not the sort of
thing that would «cause» the closure of an airport or airway.
As for Tampa ....... The fact is that all airports need to repaint their
runways every few years. The painters and the pilots prefer the runway to
be closed while this is going on. The closure need not last more than a
few hours. Sometimes they decide it would be nice to renumber the runway
in order to better align the name with the current magnetic heading ...
but this is not obligatory. Sometimes they do, and sometimes they don't.
If they do, they generally try to synchronize the renumbering with the
regularly-scheduled cycle for reissuance of the navigational charts, although
there are ways of handling an off-cycle renumbering also.
And just for fun: «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.» Wow. Not just repainting the numbers, but
given the runway a whole new _location_? That's amazing. I've seen shows
on TV where they jack up some historic house and move it to a new location
.... but relocating an entire runway?
Also: What do the signs have to do with the charts? The alleged TBT quote
sounds to me like word salad: You take parts of three potentially-reasonable
sentences, chop them up, and toss them together.
How can anybody write such a sentence? Or repeat it without giggling?
Anybody who though about it for a femtosecond would know the sentence had
to be wrong twice over. Given that a sentence by definition is supposed
to express a single idea, writing a sentence that contains two errors
requires a certain amount of ingenuity.
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