17 ms·

Plans to shift aviation from magnetic navigation to true navigation

262 points by tankenmate 5y ago

TeeMassive 5y ago
> While professional mariners stopped using the earth’s magnetic field as their primary directional reference some 50 years ago, civil aviation did not, because at that time accurate inertial navigation systems (INS) were too heavy and bulky for aircraft use. Ships do not sink if they get lost with no fuel.
tzs 5y ago
OT: looking at the maps on FlightAware, Flightradar24, and similar sites and seeing the vast number of planes crisscrossing the US at any one time I wonder if it would be possible to do a peer to peer navigation system? A plane at 30k feet should have line of sight to any other plane within about 200 miles, and even farther the higher up the other plane is. If the other plane is at 30k feet, it should be in line of sight at about 400 miles. Have a way for planes to exchange information with other planes that are in of sight about where they are heading and how confident they are that they are on the right heading. So let us say you've got a plane flying from Los Angeles to New York. You see what other planes you can see. That should include others that are going to New York but are ahead of yours. Find out from those who confident they are that they are on course, and use that to figure out a good course for you to follow and an estimate of how confident you are in that course. You in turn provide your course information to other planes heading to New York that are behind you. I think you could probably make a viable system with omnidirectional transmitters on planes for broadcasting course and confidence information, and directional receivers for receiving those broadcasts. I've sometimes wondered if some whales use a system like this. I remember reading once about some species of whale (I totally have forgotten which species and even where they lived) that had a long annual migration. Researchers had attached GPS trackers to several of the whales and recorded their routes. The researchers were surprised by how direct the routes were. The various ways they had hypothesized that the whales might navigate would have enough uncertainty that they expect the routes to have a lot more deviation from the direct route. The number of whales they attached trackers to was only a small fraction of the number of whales in the migration, and from what I read the migration doesn't start all at once. As the weather turns more and more whales start the migration. Suppose the whales navigate like I suggested above for planes. The whales that leave early or using the imprecise methods that the researchers hypothesized. They go in the right general direction using clues like sun position, but can get quite a ways to the side of the straight route, such as when they lose sight of the sun. The whales that leave a little latter would do the same thing. But the ones behind would also be able to hear the calls of the ones ahead. If they can tell what direction those are coming from, they can use that as a navigation input. If there are several ahead going toward the average position of the leaders should put the follows on a more direct route. Even if there is only one ahead that you are following, as long as that one is on average going in the right direction you should end up on a more direct route. That's because if the leader is drifting side to side and you are going toward them which causes you to also drift side to side your drifts should have a smaller amplitude. Those farther back following you will have even smaller drifts. The ones following your followers will be doing even better, and so on. If the whales the researchers attached trackers to where all far enough back in the migration, the above mechanism might explain what the researchers saw.
joncrane 5y ago
Neat article, but I have a question that's kind of a tangent: what are those rose-colored lenses that the pilots have flipped down to look through the windshield of the plane in the picture?
- BrentOzar 5y ago
  A heads-up display: https://www.flyingmag.com/how-it-works-head-up-display/ https://www.flyingmag.com/how-it-works-head-up-display/
- this_is_not_you 5y ago
  My first guess would be heads-up displays. On photos they always appear blank.
kumarharsh 5y ago
Kinda funny that the aviation industry cannot implement the more accurate inertial navigation systems (INS) right now because: "The biggest single problem in trying to implement this change worldwide would be inertia" XD
- dogma1138 5y ago
  Outside of military uses when GNSS can be jammed INS is pointless when GNSS is available. INS that is accurate is very expensive to build and maintain. INS that isn’t reliant on external inputs including from a magnetic compass for calibration is even more so.
  - cm2187 5y ago
    The SR71 was using stars to navigate!
    - ampdepolymerase 5y ago
      You need clear view of the sky and big lenses (you can always use more compact metamaterial lenses and infrared imaging for cloudy days but they are as expensive if not more than INS). Star charts also drift over the years and you will have the same problem as magnetic true north where the database needs to be updated regularly. Fine for airliners, not so great for skyhawks.
      - cm2187 5y ago
        Yeah I guess that wouldn’t work during takeoff and landing. But for the most common airliners (a320 to a380 and boeing equivalent): are there clouds above their cruising altitude? By day I presume you could use the sun.
        p_l 5y ago
        Some early jetliners had special cupola for star navigation, but it soon fell out of use because NDB, VOR, DME and other radio systems were easier and better.
throw0101a 5y ago
There are a lot of old Cessna-type planes out there in the US (and to a certain extent Canada) that act as the backbone of the pilot training pipeline: what will it take to update all of those? (And a whole bunch are owned 'for fun'.) I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with.
- sleepysysadmin 5y ago
  >I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with. Have us Canucks even done ADS-B? The USA is way ahead of us on that one.
  - _n_b_ 5y ago
    "Meanwhile, the ADS-B mandate in Canada has been under an indefinite suspension since November 2019. It was originally slated to begin in February 2021 but was placed on hold in response to stakeholder feedback." https://www.ainonline.com/aviation-news/business-aviation/2021-07-15/transport-canada-revises-ads-b-advisory-circular https://www.ainonline.com/aviation-news/business-aviation/20...
    - sleepysysadmin 5y ago
      Thanks, couldn't find anything. I knew that happened years ago and didn't hear much.
    - throw0101a 5y ago
      IIRC a major sticking point was "antenna diversity": in addition to having something point down, Nav Canada wanted antennas pointing up for space-based ADS-B (NavCanada was an initial investor in Aireon). But the extra antenna is still a bit pricey, but given Canada's vastness, satellites were the only way to get good overage outside of major urban areas. NavCanada/Aireon would also be using 1090ES and not the UAT that the US allows for lower-flying GA planes as well. However, if you're near the US border, your transponder can (IIRC) broadcast that you have an UAT receiver on-board (even if you have an 1090 transmitter), and the FAA's gear may send out UAT data (e.g., weather, UAT planes). * https://skiesmag.com/features/diversity-matters-canadas-performance-requirements/ https://skiesmag.com/features/diversity-matters-canadas-perf...
euroderf 5y ago
GPS goes down or is spoofed or blocked, a solar storm hits, software bugs & crashes, how many RISKS to the public ?
- wwn_se 5y ago
  GPS is not involved in this change really. Solar storms affect the magnetic field of earth to. Magnetic north is just a sensor going through software like everything else. Less risk... not more.
  - rob74 5y ago
    Er... I get it that it's about changing the "reference system" and not primarily about GPS. But the difference between "magnetic North" and "true North" depends on your position, and how are you going to get your position if not using GPS?
    - jcrawfordor 5y ago
      Using a wide variety of "traditional" techniques that range from dead reckoning (or "pilotage" which is dead reckoning corrected by landmarks) to politely asking a controller if they have you on radar. Airplanes operated under challenging conditions without falling out of the sky for a long time before GPS became a ubiquitous flight instrument (pretty recently, really).
  - chrisseaton 5y ago
    > GPS is not involved in this change really. How do you determine true north without a GPS system?
    - lxgr 5y ago
      Wouldn't it be possible to broadcast local magnetic declination over ATIS or other automated broadcast systems? As far as I know (and according to the article), modern navigation systems contain databases of the local magnetic declination anyway; instead of updating maps and navigational databases, we could just update these declination database instead every once in a while if I understand it correctly.
defenestration 5y ago
The article mentions that the magnetic field of the earth is changing more rapidly. Why is that?
- tankenmate 5y ago
  It goes through cycles naturally and from time to time the magnetic poles flip (it happens every few hundred thousand years). The magnetic field is largely created by the movement of molten iron and nickel in the earth's outer core. Wikipedia has a pretty good article on it.[0] [0] https://en.wikipedia.org/wiki/Earth's_magnetic_field https://en.wikipedia.org/wiki/Earth's_magnetic_field
  - jcims 5y ago
    Whoa it looks like we're estimating it takes ~7000 years for it to complete the flip. https://www.nsf.gov/news/news_summ.jsp?cntn_id=100358 https://www.nsf.gov/news/news_summ.jsp?cntn_id=100358 Biology appears to survive it but I'm curious what happens to our digital ecosystem when we lose a portion of our protection against charged particles.
- BurningFrog 5y ago
  No one knows. We just observe it happening.
- phkahler 5y ago
  >> The article mentions that the magnetic field of the earth is changing more rapidly. Why is that? It is heading toward Russia. Putin is a super villain and he's stealing the north pole.
Grustaf 5y ago
What is the advantage though? True North is of course easier to understand and use when navigating manually, but what's the benefit in a commercial airliner?
- KineticLensman 5y ago
  TFA doesn't precisely enumerate them but two I saw were: * removes the ongoing process / cost of updating mag tracks as the Earth's magnetic field shifts * avoids errors that occur when the true/mag difference is correctly specified
- maxerickson 5y ago
  It removes the need to maintain the lookup tables that are used to compute magnetic north from the true north determined by the navigation system. I don't know anything about them, but looking it up, apparently inertial navigation systems can determine true north by sensing the spin axis of the planet! So it isn't just a 'gps is easier' kind of thing.
- andylynch 5y ago
  There are two main ones 1. modern navigation systems often work in true North already but have to map to magnetic for display & to match charts. 2. magnetic north moves! This greatly complicates how you deal with the first point. I don’t envy the Canadian pilots they were talking about who tested some of this current stuff, and found their plane’s idea of the runway direction way very different from where it lay.
- dan_hawkins 5y ago
  First Air Flight 6560 crash [0] [0] https://en.wikipedia.org/wiki/First_Air_Flight_6560 https://en.wikipedia.org/wiki/First_Air_Flight_6560
  - dan_hawkins 5y ago
    PS: I highly recommend crash analysis written by Admiral Cloudberg. In the above case: [0] Arctic Approach: The crash of First Air flight 6560 [0] https://admiralcloudberg.medium.com/arctic-approach-the-crash-of-first-air-flight-6560-8949c8716ea9 https://admiralcloudberg.medium.com/arctic-approach-the-cras...
pridkett 5y ago
This is really fascinating, but probably something that is needed. If nothing else it means airports will stop needing to re-paint their runways periodically. Tampa had to repaint runways in 2011, Stansted had to do it in 2009 and thinks they’ll need to do it again in 2055 [0]. Of course, to get there we’ll have to repaint a lot of runways and replace a lot of signage for runways that currently correspond to magnetic north. [0]: https://phys.org/news/2011-01-tampa-airport-runways-renumbered-due.html https://phys.org/news/2011-01-tampa-airport-runways-renumber...
- closewith 5y ago
  > If nothing else it means airports will stop needing to re-paint their runways periodically. Airports have to repaint their runways far more frequently than the multi-decade timespan it takes to shift 10 degrees due to wear-and-tear, weather, resurfacing, etc.
  - jgtrosh 5y ago
    I'd wager that maintenance repaint (in place) is less costly than repainting at a different location, which requires additional expertise
    - p_l 5y ago
      you do not repaint in different place, you change the numbers at most, because unless you rebuild the runway you're not going to change its axis to which paint marks locations are referenced.
      - d1str0 5y ago
        You can’t just arbitrarily change numbers though. Lots of documentation needs to be updated with a number change.
        p_l 5y ago
        True. But I'd say not as much as people might think, assuming (oops) that people check NOTAMs
ls65536 5y ago
Related to this topic, here's an interesting NOAA site with more details about Earth's magnetic declination and containing lots of data about how it changes spatially and temporally: https://ngdc.noaa.gov/geomag/declination.shtml https://ngdc.noaa.gov/geomag/declination.shtml They even have detailed data for predictions about how it is likely to change in the coming years (presently up until the year 2025).
- AshamedCaptain 5y ago
  > They even have detailed data for predictions about how it is likely to change in the coming years (presently up until the year 2025). They have been publishing the models in 5-year packages for as long as I can remember (e.g. previous one was 2015-2020 model, and so forth). I still have 30 year old devices/PDAs/GPSs that see firmware updates just for the magnetic declination models. Curious how they do it these days, since all these devices with a compass need these up-to-date models. Likely they just phone home every time. :(
  - ls65536 5y ago
    It probably depends on the specific application, but I would imagine the models/data that various devices in the field are using are probably updated as part of some periodic maintenance schedule. They don't change significantly enough or quickly enough to demand online updates that frequently, but I suppose every device manufacturer/maintainer has their own way of doing it for whatever reasons they might have. In my own work, I've downloaded the dataset from NOAA and their tools to parse and work with this data to generate my own global 1-degree by 1-degree by 1-year "grid" for magnetic declination [0], along with some code [1] to read this data and be able to give you an estimated value for magnetic declination for any position on the globe for any time instant between 2020 and 2025. Before 2025, I will probably need to download the new data, run the tools again, and update my own dataset (to include values for 2025-2030 or whatever the case may be), but this will definitely be a manual process. [0] https://github.com/ls4096/sailnavsim-core/blob/master/compass_data/mag_dec.csv https://github.com/ls4096/sailnavsim-core/blob/master/compas... [1] https://github.com/ls4096/libproteus/blob/v0.6.2/include/proteus/Compass.h#L60 https://github.com/ls4096/libproteus/blob/v0.6.2/include/pro...
temptemptemp111 5y ago
Wouldn't want more people realizing the nature of the earth!
phkahler 5y ago
Awe man, they just moved the runways at my local airport a couple years ago to align with the newer magnetic north. It used to be 18/36 and 9/27. After the move it's 1/19 and 10/28.
maxcan 5y ago
Its kind of funny. In our initial training the FAA requires that instructors really drill it into our heads when we using magnetic vs true numbers then as soon as you pass your first check ride you basically never think about it again. I've been flying since 2013 with almost 500 hours at this point. I could make some educated guesses about where we use true vs magnetic, but aside from runway designations couldn't tell you much for certain. Its never come up in my flying.
- ah88 5y ago
  CFI here. It’s not a big deal in most of the country but the Pacific Northwest does have variation of about 20 degrees. It can make a difference when calculating takeoff and landing data as winds are true but runways are magnetic.
  - bronco21016 5y ago
    I think it’s important to point out the nuance. Observational winds (eg METAR) are recorded in true. Reported winds (ATIS, ASOS, AWOS) are given in magnetic. [1] The adage goes “If you read it, it’s true. If you heard it, it’s magnetic.” [1] https://www.faa.gov/documentLibrary/media/Order/7900_5D.pdf https://www.faa.gov/documentLibrary/media/Order/7900_5D.pdf Chapter 7.4
    - barbazoo 5y ago
      What if you read the ATIS though? /s
      - maxcan 5y ago
        one of my favorite apocryphal exchanges: airplane inbound to land: "KXYZ tower, N12345 at 3000' tower: "N12345, KXYZ tower, confirm you have Romeo" airplane: "KXYZ tower, N12345 has Romeo" tower: "N12345, fine, but bravo is current, recommend you recheck atis"
        5y ago
dosman33 5y ago
With how much the military has been practicing for situations where GNSS will be jammed in the past few years it seems... overly optimistic to coerce the entire industry to ditch the magnetic compass at this point. https://www.thedrive.com/the-war-zone/17987/usaf-is-jamming-gps-in-the-western-u-s-for-largest-ever-red-flag-air-war-exercise https://www.thedrive.com/the-war-zone/17987/usaf-is-jamming-... https://www.thedrive.com/the-war-zone/15194/russia-jammed-phones-and-gps-in-northern-europe-during-massive-military-drills https://www.thedrive.com/the-war-zone/15194/russia-jammed-ph... FAA issued NOTAMs (Notices To Airmen) reveal a lot of deliberate GNSS jamming across the US around military bases, it's not just limited to the Nelis area: https://notaminfo.com/explain?id=1630592 https://notaminfo.com/explain?id=1630592 Also Russia enjoys just messing with GPS to annoy NATO exercises, so you never know when you might fly through an area of active GNSS denial: https://www.ofcom.org.uk/spectrum/information/gps-jamming-exercises https://www.ofcom.org.uk/spectrum/information/gps-jamming-ex...
- deleted 5y ago
  [deleted]
- willis936 5y ago
  Magnetic variation can be pretty dramatic, especially at latitudes past the tropics. It's reasonable to use a combination of magnetic compass with dead reckoning.
  - lazide 5y ago
    And ever changing - drift is quite visible over a decade or so, and using old maps can cause real problems if you’re only using magnetic when you get even as far north as Seattle.
    - ls65536 5y ago
      And this is why when doing any sort of navigation activity you should always check the publish dates on your maps/charts and act accordingly!
MayeulC 5y ago
I have some training as a VFR pilot (for ultralight aircraft). I was under the impression that true north was always used everywhere (maps mainly), and adjusted with the local (and current) magnetic deviation when preparing the flight plan, to be able to take accurate bearings. Using magnetic north in maps and databases seems... misguided. Not updating instruments with the latest value too, although it must be a lot more complex to do so over long flights, with non-negligible deviation changes. Don't lose your bearings! I can imagine it's easy to rely too much on instruments when they're available.
literallyaduck 5y ago
I wonder if someone got intel that we are about to have a pole reversal or it might stop working completely.
aj7 5y ago
Bad idea. Wouldn’t want to be flying over water in Asia when China decides to invade Taiwan with just GPS.
captainredbeard 5y ago
Just more money for the avionics shops
AdrianB1 5y ago
As a GA pilot, one of the complications of the navigation exams for small planes was navigation and calculation of magnetic versus true and the entire range of derivations. It was mostly useless because of the local legislation demand to fly only in visual conditions (IFR not allowed for small planes), but it made the exams unnecessarily harder. The ever worse part was the demand to be able to calculate a flight path to something like New York, where Earth curvature matters, for planes that cannot fly more than 1000km at low altitude and speed, so they are never allowed to fly over the ocean or on distances big enough to have a significant difference between a straight line on the map and the shortest route. I am happy to see at least one of these going away, even in 9 years.
FabHK 5y ago
While you're at it, please shift to metric! Feet for altitude, nautical miles for distance, statute miles for visibility, metres for runway visual range (most often)... Take a plane that has a glide ratio of 1:10, say. It's 1 km high. How far can it glide? 10 km. Now it's 3000 ft high. How far can it glide, in nautical miles?
- benhurmarcel 5y ago
  Interestingly, glider pilots in metric countries use metric units.
- uncoder0 5y ago
  My mental math told me ~5 nautical miles, I checked and I was off by 0.07. Metric would be nice but most people who have flown can do the rough math in their heads.
watersb 5y ago
IIRC, non-uniform magnetic variation in northwest New Mexico: not aliens or jamming. Just some differences in composition of the Earth around there. In addition to the drift of magnetic north, it's important to keep in mind that there are local variations. These are indicated on aeronautical charts but take some getting used to.
f3rnando 5y ago
I prefer Right navigation :P https://en.wikipedia.org/wiki/Magnetic_declination https://en.wikipedia.org/wiki/Magnetic_declination

262 points by tankenmate 5y ago

> While professional mariners stopped using the earth’s magnetic field as their primary directional reference some 50 years ago, civil aviation did not, because at that time accurate inertial navigation systems (INS) were too heavy and bulky for aircraft use. Ships do not sink if they get lost with no fuel.

tzs 5y ago

OT: looking at the maps on FlightAware, Flightradar24, and similar sites and seeing the vast number of planes crisscrossing the US at any one time I wonder if it would be possible to do a peer to peer navigation system? A plane at 30k feet should have line of sight to any other plane within about 200 miles, and even farther the higher up the other plane is. If the other plane is at 30k feet, it should be in line of sight at about 400 miles. Have a way for planes to exchange information with other planes that are in of sight about where they are heading and how confident they are that they are on the right heading. So let us say you've got a plane flying from Los Angeles to New York. You see what other planes you can see. That should include others that are going to New York but are ahead of yours. Find out from those who confident they are that they are on course, and use that to figure out a good course for you to follow and an estimate of how confident you are in that course. You in turn provide your course information to other planes heading to New York that are behind you. I think you could probably make a viable system with omnidirectional transmitters on planes for broadcasting course and confidence information, and directional receivers for receiving those broadcasts. I've sometimes wondered if some whales use a system like this. I remember reading once about some species of whale (I totally have forgotten which species and even where they lived) that had a long annual migration. Researchers had attached GPS trackers to several of the whales and recorded their routes. The researchers were surprised by how direct the routes were. The various ways they had hypothesized that the whales might navigate would have enough uncertainty that they expect the routes to have a lot more deviation from the direct route. The number of whales they attached trackers to was only a small fraction of the number of whales in the migration, and from what I read the migration doesn't start all at once. As the weather turns more and more whales start the migration. Suppose the whales navigate like I suggested above for planes. The whales that leave early or using the imprecise methods that the researchers hypothesized. They go in the right general direction using clues like sun position, but can get quite a ways to the side of the straight route, such as when they lose sight of the sun. The whales that leave a little latter would do the same thing. But the ones behind would also be able to hear the calls of the ones ahead. If they can tell what direction those are coming from, they can use that as a navigation input. If there are several ahead going toward the average position of the leaders should put the follows on a more direct route. Even if there is only one ahead that you are following, as long as that one is on average going in the right direction you should end up on a more direct route. That's because if the leader is drifting side to side and you are going toward them which causes you to also drift side to side your drifts should have a smaller amplitude. Those farther back following you will have even smaller drifts. The ones following your followers will be doing even better, and so on. If the whales the researchers attached trackers to where all far enough back in the migration, the above mechanism might explain what the researchers saw.

joncrane 5y ago

Neat article, but I have a question that's kind of a tangent: what are those rose-colored lenses that the pilots have flipped down to look through the windshield of the plane in the picture?

BrentOzar 5y ago
A heads-up display: https://www.flyingmag.com/how-it-works-head-up-display/ https://www.flyingmag.com/how-it-works-head-up-display/
this_is_not_you 5y ago
My first guess would be heads-up displays. On photos they always appear blank.

kumarharsh 5y ago

Kinda funny that the aviation industry cannot implement the more accurate inertial navigation systems (INS) right now because: "The biggest single problem in trying to implement this change worldwide would be inertia" XD

dogma1138 5y ago
Outside of military uses when GNSS can be jammed INS is pointless when GNSS is available. INS that is accurate is very expensive to build and maintain. INS that isn’t reliant on external inputs including from a magnetic compass for calibration is even more so.
- cm2187 5y ago
  The SR71 was using stars to navigate!
  - ampdepolymerase 5y ago
    You need clear view of the sky and big lenses (you can always use more compact metamaterial lenses and infrared imaging for cloudy days but they are as expensive if not more than INS). Star charts also drift over the years and you will have the same problem as magnetic true north where the database needs to be updated regularly. Fine for airliners, not so great for skyhawks.
    - cm2187 5y ago
      Yeah I guess that wouldn’t work during takeoff and landing. But for the most common airliners (a320 to a380 and boeing equivalent): are there clouds above their cruising altitude? By day I presume you could use the sun.
      - p_l 5y ago
        Some early jetliners had special cupola for star navigation, but it soon fell out of use because NDB, VOR, DME and other radio systems were easier and better.

throw0101a 5y ago

There are a lot of old Cessna-type planes out there in the US (and to a certain extent Canada) that act as the backbone of the pilot training pipeline: what will it take to update all of those? (And a whole bunch are owned 'for fun'.) I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with.

sleepysysadmin 5y ago
>I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with. Have us Canucks even done ADS-B? The USA is way ahead of us on that one.
- _n_b_ 5y ago
  "Meanwhile, the ADS-B mandate in Canada has been under an indefinite suspension since November 2019. It was originally slated to begin in February 2021 but was placed on hold in response to stakeholder feedback." https://www.ainonline.com/aviation-news/business-aviation/2021-07-15/transport-canada-revises-ads-b-advisory-circular https://www.ainonline.com/aviation-news/business-aviation/20...
  - sleepysysadmin 5y ago
    Thanks, couldn't find anything. I knew that happened years ago and didn't hear much.
  - throw0101a 5y ago
    IIRC a major sticking point was "antenna diversity": in addition to having something point down, Nav Canada wanted antennas pointing up for space-based ADS-B (NavCanada was an initial investor in Aireon). But the extra antenna is still a bit pricey, but given Canada's vastness, satellites were the only way to get good overage outside of major urban areas. NavCanada/Aireon would also be using 1090ES and not the UAT that the US allows for lower-flying GA planes as well. However, if you're near the US border, your transponder can (IIRC) broadcast that you have an UAT receiver on-board (even if you have an 1090 transmitter), and the FAA's gear may send out UAT data (e.g., weather, UAT planes). * https://skiesmag.com/features/diversity-matters-canadas-performance-requirements/ https://skiesmag.com/features/diversity-matters-canadas-perf...

euroderf 5y ago

GPS goes down or is spoofed or blocked, a solar storm hits, software bugs & crashes, how many RISKS to the public ?

wwn_se 5y ago
GPS is not involved in this change really. Solar storms affect the magnetic field of earth to. Magnetic north is just a sensor going through software like everything else. Less risk... not more.
- rob74 5y ago
  Er... I get it that it's about changing the "reference system" and not primarily about GPS. But the difference between "magnetic North" and "true North" depends on your position, and how are you going to get your position if not using GPS?
  - jcrawfordor 5y ago
    Using a wide variety of "traditional" techniques that range from dead reckoning (or "pilotage" which is dead reckoning corrected by landmarks) to politely asking a controller if they have you on radar. Airplanes operated under challenging conditions without falling out of the sky for a long time before GPS became a ubiquitous flight instrument (pretty recently, really).
- chrisseaton 5y ago
  > GPS is not involved in this change really. How do you determine true north without a GPS system?
  - lxgr 5y ago
    Wouldn't it be possible to broadcast local magnetic declination over ATIS or other automated broadcast systems? As far as I know (and according to the article), modern navigation systems contain databases of the local magnetic declination anyway; instead of updating maps and navigational databases, we could just update these declination database instead every once in a while if I understand it correctly.

defenestration 5y ago

The article mentions that the magnetic field of the earth is changing more rapidly. Why is that?

tankenmate 5y ago
It goes through cycles naturally and from time to time the magnetic poles flip (it happens every few hundred thousand years). The magnetic field is largely created by the movement of molten iron and nickel in the earth's outer core. Wikipedia has a pretty good article on it.[0] [0] https://en.wikipedia.org/wiki/Earth's_magnetic_field https://en.wikipedia.org/wiki/Earth's_magnetic_field
- jcims 5y ago
  Whoa it looks like we're estimating it takes ~7000 years for it to complete the flip. https://www.nsf.gov/news/news_summ.jsp?cntn_id=100358 https://www.nsf.gov/news/news_summ.jsp?cntn_id=100358 Biology appears to survive it but I'm curious what happens to our digital ecosystem when we lose a portion of our protection against charged particles.
BurningFrog 5y ago
No one knows. We just observe it happening.
phkahler 5y ago
>> The article mentions that the magnetic field of the earth is changing more rapidly. Why is that? It is heading toward Russia. Putin is a super villain and he's stealing the north pole.

Grustaf 5y ago

What is the advantage though? True North is of course easier to understand and use when navigating manually, but what's the benefit in a commercial airliner?

KineticLensman 5y ago
TFA doesn't precisely enumerate them but two I saw were: * removes the ongoing process / cost of updating mag tracks as the Earth's magnetic field shifts * avoids errors that occur when the true/mag difference is correctly specified
maxerickson 5y ago
It removes the need to maintain the lookup tables that are used to compute magnetic north from the true north determined by the navigation system. I don't know anything about them, but looking it up, apparently inertial navigation systems can determine true north by sensing the spin axis of the planet! So it isn't just a 'gps is easier' kind of thing.
andylynch 5y ago
There are two main ones 1. modern navigation systems often work in true North already but have to map to magnetic for display & to match charts. 2. magnetic north moves! This greatly complicates how you deal with the first point. I don’t envy the Canadian pilots they were talking about who tested some of this current stuff, and found their plane’s idea of the runway direction way very different from where it lay.
dan_hawkins 5y ago
First Air Flight 6560 crash [0] [0] https://en.wikipedia.org/wiki/First_Air_Flight_6560 https://en.wikipedia.org/wiki/First_Air_Flight_6560
- dan_hawkins 5y ago
  PS: I highly recommend crash analysis written by Admiral Cloudberg. In the above case: [0] Arctic Approach: The crash of First Air flight 6560 [0] https://admiralcloudberg.medium.com/arctic-approach-the-crash-of-first-air-flight-6560-8949c8716ea9 https://admiralcloudberg.medium.com/arctic-approach-the-cras...

pridkett 5y ago

This is really fascinating, but probably something that is needed. If nothing else it means airports will stop needing to re-paint their runways periodically. Tampa had to repaint runways in 2011, Stansted had to do it in 2009 and thinks they’ll need to do it again in 2055 [0]. Of course, to get there we’ll have to repaint a lot of runways and replace a lot of signage for runways that currently correspond to magnetic north. [0]: https://phys.org/news/2011-01-tampa-airport-runways-renumbered-due.html https://phys.org/news/2011-01-tampa-airport-runways-renumber...

closewith 5y ago
> If nothing else it means airports will stop needing to re-paint their runways periodically. Airports have to repaint their runways far more frequently than the multi-decade timespan it takes to shift 10 degrees due to wear-and-tear, weather, resurfacing, etc.
- jgtrosh 5y ago
  I'd wager that maintenance repaint (in place) is less costly than repainting at a different location, which requires additional expertise
  - p_l 5y ago
    you do not repaint in different place, you change the numbers at most, because unless you rebuild the runway you're not going to change its axis to which paint marks locations are referenced.
    - d1str0 5y ago
      You can’t just arbitrarily change numbers though. Lots of documentation needs to be updated with a number change.
      - p_l 5y ago
        True. But I'd say not as much as people might think, assuming (oops) that people check NOTAMs

ls65536 5y ago

Related to this topic, here's an interesting NOAA site with more details about Earth's magnetic declination and containing lots of data about how it changes spatially and temporally: https://ngdc.noaa.gov/geomag/declination.shtml https://ngdc.noaa.gov/geomag/declination.shtml They even have detailed data for predictions about how it is likely to change in the coming years (presently up until the year 2025).

AshamedCaptain 5y ago
> They even have detailed data for predictions about how it is likely to change in the coming years (presently up until the year 2025). They have been publishing the models in 5-year packages for as long as I can remember (e.g. previous one was 2015-2020 model, and so forth). I still have 30 year old devices/PDAs/GPSs that see firmware updates just for the magnetic declination models. Curious how they do it these days, since all these devices with a compass need these up-to-date models. Likely they just phone home every time. :(
- ls65536 5y ago
  It probably depends on the specific application, but I would imagine the models/data that various devices in the field are using are probably updated as part of some periodic maintenance schedule. They don't change significantly enough or quickly enough to demand online updates that frequently, but I suppose every device manufacturer/maintainer has their own way of doing it for whatever reasons they might have. In my own work, I've downloaded the dataset from NOAA and their tools to parse and work with this data to generate my own global 1-degree by 1-degree by 1-year "grid" for magnetic declination [0], along with some code [1] to read this data and be able to give you an estimated value for magnetic declination for any position on the globe for any time instant between 2020 and 2025. Before 2025, I will probably need to download the new data, run the tools again, and update my own dataset (to include values for 2025-2030 or whatever the case may be), but this will definitely be a manual process. [0] https://github.com/ls4096/sailnavsim-core/blob/master/compass_data/mag_dec.csv https://github.com/ls4096/sailnavsim-core/blob/master/compas... [1] https://github.com/ls4096/libproteus/blob/v0.6.2/include/proteus/Compass.h#L60 https://github.com/ls4096/libproteus/blob/v0.6.2/include/pro...

temptemptemp111 5y ago

Wouldn't want more people realizing the nature of the earth!

phkahler 5y ago

Awe man, they just moved the runways at my local airport a couple years ago to align with the newer magnetic north. It used to be 18/36 and 9/27. After the move it's 1/19 and 10/28.

maxcan 5y ago

Its kind of funny. In our initial training the FAA requires that instructors really drill it into our heads when we using magnetic vs true numbers then as soon as you pass your first check ride you basically never think about it again. I've been flying since 2013 with almost 500 hours at this point. I could make some educated guesses about where we use true vs magnetic, but aside from runway designations couldn't tell you much for certain. Its never come up in my flying.

ah88 5y ago
CFI here. It’s not a big deal in most of the country but the Pacific Northwest does have variation of about 20 degrees. It can make a difference when calculating takeoff and landing data as winds are true but runways are magnetic.
- bronco21016 5y ago
  I think it’s important to point out the nuance. Observational winds (eg METAR) are recorded in true. Reported winds (ATIS, ASOS, AWOS) are given in magnetic. [1] The adage goes “If you read it, it’s true. If you heard it, it’s magnetic.” [1] https://www.faa.gov/documentLibrary/media/Order/7900_5D.pdf https://www.faa.gov/documentLibrary/media/Order/7900_5D.pdf Chapter 7.4
  - barbazoo 5y ago
    What if you read the ATIS though? /s
    - maxcan 5y ago
      one of my favorite apocryphal exchanges: airplane inbound to land: "KXYZ tower, N12345 at 3000' tower: "N12345, KXYZ tower, confirm you have Romeo" airplane: "KXYZ tower, N12345 has Romeo" tower: "N12345, fine, but bravo is current, recommend you recheck atis"
      - 5y ago

dosman33 5y ago

With how much the military has been practicing for situations where GNSS will be jammed in the past few years it seems... overly optimistic to coerce the entire industry to ditch the magnetic compass at this point. https://www.thedrive.com/the-war-zone/17987/usaf-is-jamming-gps-in-the-western-u-s-for-largest-ever-red-flag-air-war-exercise https://www.thedrive.com/the-war-zone/17987/usaf-is-jamming-... https://www.thedrive.com/the-war-zone/15194/russia-jammed-phones-and-gps-in-northern-europe-during-massive-military-drills https://www.thedrive.com/the-war-zone/15194/russia-jammed-ph... FAA issued NOTAMs (Notices To Airmen) reveal a lot of deliberate GNSS jamming across the US around military bases, it's not just limited to the Nelis area: https://notaminfo.com/explain?id=1630592 https://notaminfo.com/explain?id=1630592 Also Russia enjoys just messing with GPS to annoy NATO exercises, so you never know when you might fly through an area of active GNSS denial: https://www.ofcom.org.uk/spectrum/information/gps-jamming-exercises https://www.ofcom.org.uk/spectrum/information/gps-jamming-ex...

deleted 5y ago
[deleted]
willis936 5y ago
Magnetic variation can be pretty dramatic, especially at latitudes past the tropics. It's reasonable to use a combination of magnetic compass with dead reckoning.
- lazide 5y ago
  And ever changing - drift is quite visible over a decade or so, and using old maps can cause real problems if you’re only using magnetic when you get even as far north as Seattle.
  - ls65536 5y ago
    And this is why when doing any sort of navigation activity you should always check the publish dates on your maps/charts and act accordingly!

MayeulC 5y ago

I have some training as a VFR pilot (for ultralight aircraft). I was under the impression that true north was always used everywhere (maps mainly), and adjusted with the local (and current) magnetic deviation when preparing the flight plan, to be able to take accurate bearings. Using magnetic north in maps and databases seems... misguided. Not updating instruments with the latest value too, although it must be a lot more complex to do so over long flights, with non-negligible deviation changes. Don't lose your bearings! I can imagine it's easy to rely too much on instruments when they're available.

literallyaduck 5y ago

I wonder if someone got intel that we are about to have a pole reversal or it might stop working completely.

aj7 5y ago

Bad idea. Wouldn’t want to be flying over water in Asia when China decides to invade Taiwan with just GPS.

captainredbeard 5y ago

Just more money for the avionics shops

AdrianB1 5y ago

As a GA pilot, one of the complications of the navigation exams for small planes was navigation and calculation of magnetic versus true and the entire range of derivations. It was mostly useless because of the local legislation demand to fly only in visual conditions (IFR not allowed for small planes), but it made the exams unnecessarily harder. The ever worse part was the demand to be able to calculate a flight path to something like New York, where Earth curvature matters, for planes that cannot fly more than 1000km at low altitude and speed, so they are never allowed to fly over the ocean or on distances big enough to have a significant difference between a straight line on the map and the shortest route. I am happy to see at least one of these going away, even in 9 years.

FabHK 5y ago

While you're at it, please shift to metric! Feet for altitude, nautical miles for distance, statute miles for visibility, metres for runway visual range (most often)... Take a plane that has a glide ratio of 1:10, say. It's 1 km high. How far can it glide? 10 km. Now it's 3000 ft high. How far can it glide, in nautical miles?

benhurmarcel 5y ago
Interestingly, glider pilots in metric countries use metric units.
uncoder0 5y ago
My mental math told me ~5 nautical miles, I checked and I was off by 0.07. Metric would be nice but most people who have flown can do the rough math in their heads.

watersb 5y ago

IIRC, non-uniform magnetic variation in northwest New Mexico: not aliens or jamming. Just some differences in composition of the Earth around there. In addition to the drift of magnetic north, it's important to keep in mind that there are local variations. These are indicated on aeronautical charts but take some getting used to.

f3rnando 5y ago

I prefer Right navigation :P https://en.wikipedia.org/wiki/Magnetic_declination https://en.wikipedia.org/wiki/Magnetic_declination