Slashdot Mirror
Why Airports Rename Runways When the Magnetic Poles Move (wired.com)
An anonymous reader shares a report: For decades, pilots heading into or out of Wichita Eisenhower National Airport in southeast Kansas have had three runways to choose from: 1L/19R, 1R/19L, and 14/32. Now, at the orders of the FAA, the airport will spend hundreds of thousands of dollars to give itself a makeover. Workers will repaint those huge numbers at the ends of each runway and replace copious signage. Pilots and air traffic controllers will study new reference manuals and approach plates, all updated to reflect an airport whose three runways have been renamed. World, meet 2L/20R, 2R/20L, and 15/33 -- which happen to be the same runways that have been welcoming planes since 1954.
This is not a "What's in a name?" situation. The runways may be the same sweet-smelling stretches of tarmac they've always been, but the world around them has changed. Well, the magnetic fields around the world have changed. The planet's magnetic poles -- the points that compasses recognize as north and south -- are always wandering about. That's a problem, because most runways are named for their magnetic headings. Take Wichita's 14/32. First off, because planes can land or take off from either direction, you can think of it as two runways: 14 and 32. (Pro tip: Pilots say "one-four" and "three-two," not 14 and 32.) If you're looking at a compass, one end is about 140 degrees off of north, counting clockwise. For simplicity's sake, the headings are rounded to the nearest five, and dropped to two digits. So if you're looking down at Wichita Eisenhower, runway 14/32 is the one running from the northwest to the southeast.
This is not a "What's in a name?" situation. The runways may be the same sweet-smelling stretches of tarmac they've always been, but the world around them has changed. Well, the magnetic fields around the world have changed. The planet's magnetic poles -- the points that compasses recognize as north and south -- are always wandering about. That's a problem, because most runways are named for their magnetic headings. Take Wichita's 14/32. First off, because planes can land or take off from either direction, you can think of it as two runways: 14 and 32. (Pro tip: Pilots say "one-four" and "three-two," not 14 and 32.) If you're looking at a compass, one end is about 140 degrees off of north, counting clockwise. For simplicity's sake, the headings are rounded to the nearest five, and dropped to two digits. So if you're looking down at Wichita Eisenhower, runway 14/32 is the one running from the northwest to the southeast.
Runways are numbered in 10s of degrees. 19R is the right hand runway where the approach is at 190 degrees.
The magnetic poles haven't shifted by 10 degrees, so the better question is why it was labelled 19R in the first place.
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
The old general aviation runway at San Jose International Airport was runway 29. It was exactly parallel to runways 30R and 30L, they were just built at different times and the pole wandered. The pilots all knew the deal; it seems more confusing to change everything than for pilots to just deal with it.
E pluribus unum
its says they round to nearest 5 then truncate to two digits. Perhaps it was 197-->198.
From TFA: "Things only change when the compass reading shifts a certain amount. Say the pole shifts such that the heading of 258 degrees is actually 259 degrees. That still rounds to 260, and the runway would still be called 26. But if the compass reading goes from 258 to 254, you’re now looking at runway 25."
The deviation between magnetic and geographic north depends not just on the poleâ(TM)s degree of movement, but also the angle you are away from the pole. In some areas of the US, yes, the movement has been about 10 degrees since the mid 20th century.
E pluribus unum
There are a *lot* of aircraft out there that don't have GPS systems built in, and even if they are, they are subject to failure. Airports are built to be properly usable to the lowest common denominator of available technology, and in an emergency, the lowest common denominator may well be the basic magnetic compass.
Emergencies aside, many aircraft (especially home built's, ultralights, and a lot of other non-commercial aircraft) don't bother with things like GPS.
Z
They should just use the geographical headings instead of magnetic headings.
Except, the compass on board the airplane that needs to use the runway ... is magnetic. By definition.
Don't disappoint your bird dog. Go to the range.
The Runway Naming System allows pilots to send RNS requests to the local Runway Naming Service which of course run on the local Runway Naming Server (Be aware the same acronym holds several correct definitions). Also I t is appropriate to use the designation "RNS Server", "RNS Service", or "RNS System" even though it may be redundant.
These local RNS databases are owned by the airports and are synchronized with the root RNS server several layers up in the RNS hierarchy.
While planes may choose to make RNS requests directly from the root server, for traffic management (bandwidth, not air traffic) they are strongly encouraged to maintain their own local RNS server that caches RNS data from RNS servers at levels lower from the root and geographically local to them. This may be accomplished via RNS Zone Transfers.
It must also be remember that RNS name updates may take several hours to propagate through the RNS hierarchy and for all RNS servers to update with accurate information. So while pilots may have a local cached copy while in flight from their local RNS server, care must be made to verify the RNS data with the authoritative RNS server while approaching the destination airport.
As an example the Wichita "Gandalf" runway upon local RNS resolution currently returns 14/32.
There have been recent reports of RNS spoofing and RNS cache corruption attacks being used, as well as malicious RNS database updates pushed to the RNS root servers and propagated across the RNS network. We are currently working on the next generation of secure RNS Services known as RNSSEC.
Cwm, fjord-bank glyphs vext quiz
You seriously think that surface conditions have an effect on "the global geodynamo" (the Earth's core)? The wandering of the magnetic poles isn't the result of mysterious changes thousands of miles below the surface; in general it's caused by variations in the Earth's wobbling as it spins on its axis. According to this, the relatively recent acceleration of pole movement is the result of a water deficit in India and the Caspian Sea region.
The magnetic poles have reversed many times in Earth's history. According to this, over the last 20 million years a pole reversal happens every 300,000 years or so. It's been 780,000 years since the last one, so maybe we're overdue.
The general idea is to REDUCE the number of things that a person flying with passengers in a can in the air has to think about in an emergency, under stress in low visibility conditions when the aircraft has lost GPS or other critical systems and the baby in the back seat is screaming because of ear pain from required rapid altitude changes and the tower's radio system is down ... but the magnetic compass is working as always, and the sectional chart has a nice big number that MATCHES THE COMPASS. Because you're going to land or die in the next 60 seconds. All of these things are designed around worst-case, high-stress possibilities (which almost never occur, but sometimes do).
Don't disappoint your bird dog. Go to the range.
Pilots already know how convert between magnetic and geographical headings, I would think. I think the small inconvenience is better than having outdated runway markings or having to renew them every now and then (not only on the runways themselves, but also on all charts).
Um, no. First of all, the conversion isn't consistent from place to place. For example, as you move across degrees of longitude, the angular difference between the magnetic and geographic north changes. So, your conversion changes. The last thing you want to do to a pilot is to add more shit on his plate, trying to do calculations when he could simply compare his compass and the giant number printed on the runway.
FWIW, I was a private pilot in the 80s & 90s, but gave it up when my kid was born...just didn't have time.
Just another day in Paradise
magnetic shifts aren't universal. Well, they are, but the measurement of how much they shifted isn't universal. If one is inline with the direction it moved, there is virtually zero change in magnetic compass heading, but if one is perpendicular to its movement, then there is a very large change. This rate of change gets larger the closer one is to the magnetic pole.
Z
Hey, I heard that Blockchain is going to solve this problem! Where can I invest?