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Just a note from the sites FAQ: the data is actually showing places where airplanes report LOW NAVIGATION ACCURACY via their ADS-B transponders. Since planes t
by izacus 3y ago
Just a note from the sites FAQ: the data is actually showing places where airplanes report LOW NAVIGATION ACCURACY via their ADS-B transponders.
Since planes tend to default to INS navigation with use GPS, GLONASS, Galileo or other systems to supplement the drift, it may be subject to certain data skew (e.g. if there's an area on the world where most planes aren't equipped with GPS navigation system, have poor quality navigation tech or you might be seeing "jamming" where there might just be a common place on airline route where INS drifts).
- exitb 3y agoIt should be easy to correct for - only count aircraft that actually report good navigation accuracy sometimes.
- jjwiseman 3y agoIt only counts aircraft as experiencing interference if they have previously reported high navigation accuracy on their flight, and then begin reporting low accuracy. It's not going to just show places where INS drifts. However, it may show areas, typically military, where aerobatics or hard maneuvering are taking place, which can mask an aircraft's GPS antennae from the satellites.
- bragr 3y agoTo pile on about what this actually shows, further the data is sourced from ADSB Exchange so there's only data in areas where there are sufficient participants, and skews coverage towards Europe and North America https://map.adsbexchange.com/mlat-map/ https://map.adsbexchange.com/mlat-map/
- toomuchtodo 3y agoProject owner might be able to add data from stationary GNSS reference stations to improve global coverage of positioning accuracy available. https://geodesy.noaa.gov/CORS/ https://geodesy.noaa.gov/CORS/ https://epncb.oma.be/ https://epncb.oma.be/
- jjwiseman 3y agoYou're saying aircraft are reporting position based on their INS? That seems… weird. I've also been told the opposite, that ADS-B navigation accuracy is always reported based on GNSS, not INS. What's your source? I hope this doesn't confuse the issue, because I don't think it's actually related to what you're talking about, but recently there have been reports of inertial nav systems being "corrupted", essentially, by spoofed GNSS. The hypothesis is that the INS/IRS is corrected using spoofed GNSS data after which the INS/IRS reports bad info: https://ops.group/blog/faa-warning-navigation-failures/ https://ops.group/blog/faa-warning-navigation-failures/
- izacus 3y agoErr, yeah - the airliners still mostly use INS for their navigation (with corrections, either manual or automatic, depending on equipment and age), but ADS-B indeed needs to report its location from a GNSS "High-integrity position source". So scratch the INS part.
- lxgr 3y agoPure INS should be pretty rare these days, no? I believe it's now usually a combination of multiple sources (e.g. ground-based navaids like VORs and DMEs, GNSSs/GPS, and INS to reject most spoofed signals or in case everything else fails).
- izacus 3y agoNot sure what do you mean with "pure" INS. Primary INS is still standard - as in, all the navigation is driven primarily from INS system outputs. But, as it always was, it is regularly corrected with GNSS or navaid corrections. As far as I know most airliners still don't automatically enter corrections for INS and require manual input (basically retyping of GNSS data from a screen into a keypad) to put human into the loop which can verify if GNSS is being spoofed. The pilots can alternatively do the correction using VOR/DME navaids or even their eyes if they feel like it. As far as I know, it's becoming much more common to have INS with ability to automatically correct drift from GNSS in smaller planes (and I'm sure that will make it to airliners sooner than later).
- greggsy 3y agoThat would explains why Ukraine went from mostly green around 20 February 2022, to ‘no data’ several days later.