Within Flight Tracking
What flight trackers really know
ADS-B and multilateration can identify aircraft positions, speeds and headings, but each data source has limits investigators must understand.
On this page
- What ADS B broadcasts from aircraft
- How MLAT fills some tracking gaps
- Why different flight sites can disagree
Page outline Jump by section
Introduction
When investigators try to determine whether a reported UFO was actually an aircraft, ADS-B and multilateration (MLAT) data are among the most useful sources of objective evidence. They can reveal where aircraft were, how fast they were moving, their altitude, heading and, in many cases, their identity. However, these systems do not provide a perfect or complete picture of the sky. Understanding what the data represents—and where it can fail—is essential. A missing aircraft track is not proof that no aircraft was present, and differences between tracking websites do not automatically indicate deception or hidden traffic. Instead, ADS-B and MLAT should be treated as evidence sources with known strengths and limitations. [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa…
What ADS-B broadcasts from aircraft
ADS-B stands for Automatic Dependent Surveillance–Broadcast. Aircraft equipped with ADS-B Out determine their position using onboard navigation systems and repeatedly broadcast information including location, altitude, ground speed and identification. In normal airborne operation, position and velocity information is transmitted at least once per second, providing much more frequent updates than traditional radar systems. [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa… [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa…
For UFO investigations, ADS-B data is valuable because it moves the discussion from subjective appearance to measurable geometry. A witness may describe a light that appeared stationary, accelerated suddenly or vanished. ADS-B data allows investigators to test whether a real aircraft occupied the relevant line of sight and whether its movement matched the reported behaviour.
Several common UFO misidentifications become easier to evaluate with ADS-B data:
- An aircraft flying directly towards an observer can appear almost motionless for several minutes.
- Landing lights can make distant aircraft appear unusually bright or larger than expected.
- High-altitude aircraft can seem silent even when clearly visible.
- A turn, climb or descent may create the impression of abrupt manoeuvres when viewed from a particular angle.
Because ADS-B broadcasts are received by networks of volunteer and commercial receivers, the public flight-tracking map seen by investigators is usually a reconstruction assembled from many listening stations rather than a direct feed from air traffic control. Coverage therefore depends on receiver density and signal reception. [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa… [Wikipedia]WikipediaAutomatic Dependent Surveillance–BroadcastADS-B is an aviation surveillance technology and form of electronic conspicuity in which an…
How MLAT fills some tracking gaps
Not all aircraft transmit complete ADS-B position information. Many older aircraft carry Mode S transponders that identify the aircraft but do not continuously broadcast GPS-derived coordinates. To track these aircraft, networks such as Flightradar24 use multilateration, usually abbreviated MLAT. [Flightradar24]flightradar24.comhow we track flights with mlatFlightradar24How We Track Flights with MLAT | Flightradar24 Blog13 May 2015 — For these aircraft we've developed our receivers and softwa…
MLAT works by measuring the tiny differences in arrival time of the same transponder signal at multiple ground receivers. By comparing these timing differences, software can estimate the aircraft’s position. To produce a reliable location, several receivers must hear the same transmission simultaneously. Flightradar24 notes that four or more receivers are typically required. [LinkedIn]linkedin.comLinkedInHow does Flightradar24 track aircraft?By measuring the time it takes to receive the signal from aircraft with an older Mode S tra… [2Flightradar24] Support center
For UFO investigations, MLAT can be important because an aircraft missing from a pure ADS-B dataset may still be recoverable through MLAT-derived tracks. This is particularly relevant when witnesses report unusual lights from airliners or business jets operating with older equipment.
However, MLAT has important limitations:
- Accuracy depends on receiver geometry and coverage.
- It works best at higher altitudes where signals reach many receivers.
- Coverage can be poor in remote regions or over water.
- MLAT positions usually appear with slightly greater delay than ADS-B positions.
- Position estimates are calculated rather than directly broadcast by the aircraft. Flightradar24 LinkedIn These limitations mean that an aircraft might appear on one tracking service through MLAT while remaining absent from another service that la [linkedin.com]linkedin.comLinkedInHow does Flightradar24 track aircraft?By measuring the time it takes to receive the signal from aircraft with an older Mode S tra… cks sufficient receiver coverage.
Why different flight sites can disagree
One of the most common mistakes in online UFO discussions is assuming that all flight-tracking websites display identical information. In reality, each platform uses different receiver networks, filtering policies, processing methods and historical archives. [Flightradar24]flightradar24.comFlightradar24Multilateration (MLAT)Processing the received Mode S data using MLAT data results in a small delay in the display of aircraf…
Three major factors often explain disagreements.
Receiver coverage
Aircraft visibility depends on which receivers hear the transmissions. A tracker with more receivers in a particular region may show aircraft that another service misses entirely. Coverage differences are especially noticeable at low altitude, in mountainous terrain and in sparsely populated areas. [ADS-B Exchange]adsbexchange.comADS-B ExchangeADSB Exchange API DocumentationThe ADSB Exchange API provides real-time access to live global flight data, enabling retriev…
Different tracking technologies
Some services rely heavily on ADS-B. Others supplement ADS-B with MLAT, ADS-C or additional data feeds. As a result, aircraft positions may differ slightly or appear on only one platform. Flightradar24 [Medium]medium.comADS-B 101What It Is, and What It Means to You | by FAA…ADS-B works by having aircraft avionics regularly broadcast position, velocity, and iden…
[Filtering and privacy programmes]facebook.comUS Air Force Warns of OPSEC Threat From Online Flight…ADS-B Filtering & Privacy Regulations – FlightRadar24 automatically filters mili…
Public flight trackers do not necessarily display every aircraft they receive. In the United States, programmes such as Limiting Aircraft Data Displayed (LADD) and privacy initiatives can restrict how certain aircraft appear in public feeds. Some platforms also choose to filter particular aircraft categories, while others advertise more complete displays. [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa… [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa…
For UFO investigations, this means that checking only one website can produce misleading conclusions. Experienced investigators often compare multiple sources before deciding whether aircraft traffic was present.
What missing ADS-B data does—and does not—prove
A frequent claim in UFO debates is that “nothing was on FlightRadar24”, therefore the observed object could not have been an aircraft. The logic is appealing but flawed.
Several circumstances can produce missing or incomplete tracking data:
- Poor receiver coverage.
- Aircraft operating outside the effective range of ground receivers.
- Temporary signal loss.
- GPS interference affecting ADS-B position reporting.
- Aircraft using equipment not fully represented by a particular tracking network. [aviospace.org]aviospace.orgreal time aircraft tracking networkADSBExchange And The Rise Of Unfiltered Aircraft Tracking26 May 2026 — ADSBexchange's policy of showing all aircraft without filtering ha…
- Public-display filtering or privacy restrictions. Reddit 3Flightradar24 [Federal Aviation Administration]faa.govFederal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa…
Recent aviation tracking work has also highlighted how GPS jamming and spoofing can affect aircraft position broadcasts. In some regions, tracking services increasingly use MLAT to reconstruct positions when ADS-B location information becomes unreliable. [Flightradar24]flightradar24.comFlightradar24How Flightradar24 worksMultilateration (MLAT) uses calculated data to track aircraft with older transponders. A small plane…
Consequently, the evidential value of ADS-B data is strongest when it positively correlates an aircraft with a sighting. Its absence is generally weaker evidence because multiple ordinary reasons can explain why a track is missing.
Using ADS-B and MLAT as UFO evidence
The most reliable use of ADS-B and MLAT data is not simply asking whether an aircraft appears on a map. Investigators obtain stronger results when they compare flight tracks with the witness’s exact location, viewing direction, timing and recorded imagery.
A persuasive aircraft correlation typically combines:
- Precise sighting time.
- Witness location.
- Aircraft position and altitude. [Wikipedia]WikipediaAutomatic Dependent Surveillance–BroadcastADS-B is an aviation surveillance technology and form of electronic conspicuity in which an…
- Flight path relative to the observer.
- Expected appearance of navigation lights, landing lights or contrails.
- Consistency between the reported motion and the tracked trajectory.
When those elements align, ADS-B and MLAT data often transform a seemingly mysterious aerial observation into an identified aircraft. At the same time, the limitations of receiver networks, tracking methods and public data availability mean that investigators must avoid treating flight-tracker maps as complete representations of everything in the sky. ADS-B and MLAT are powerful datasets, but they are best understood as evidence tools rather than definitive proof either for or against a UFO explanation. [Flightradar24 Support center+3Federal Aviation Administration+3Federal Aviation Administration]
Amazon book picks
Further Reading
Books and field guides related to What flight trackers really know. Use these as the next step if you want deeper reading beyond the article.
The 1090 Megahertz Riddle
Directly explains ADS-B, tracking data, coverage limitations and aircraft surveillance.
The UFO Experience
Shows how objective evidence can transform unidentified reports into identified objects.
Stick and Rudder: An Explanation of the Art of Flying
Helps readers understand aircraft motion and observer interpretation.
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Endnotes
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/Automatic_Dependent_Surveillance%E2%80%93BroadcastSource snippet
Automatic Dependent Surveillance–BroadcastADS-B is an aviation surveillance technology and form of electronic conspicuity in which an...
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Source: flightradar24.com
Title: how we track flights with mlat
Link: https://www.flightradar24.com/blog/inside-flightradar24/how-we-track-flights-with-mlat/Source snippet
Flightradar24How We Track Flights with MLAT | Flightradar24 Blog13 May 2015 — For these aircraft we've developed our receivers and softwa...
Published: May 2015
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Source: linkedin.com
Link: https://www.linkedin.com/pulse/how-does-flightradar24-track-aircraft-flightradar24-ab-w8d6eSource snippet
LinkedInHow does Flightradar24 track aircraft?By measuring the time it takes to receive the signal from aircraft with an older Mode S tra...
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Source: flightradar24.com
Link: https://www.flightradar24.com/how-it-works/mlatSource snippet
Flightradar24Multilateration (MLAT)Processing the received Mode S data using MLAT data results in a small delay in the display of aircraf...
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Source: flightradar24.com
Link: https://www.flightradar24.com/how-it-worksSource snippet
Flightradar24How Flightradar24 worksMultilateration (MLAT) uses calculated data to track aircraft with older transponders. A small plane...
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Source: reddit.com
Link: https://www.reddit.com/r/ADSB/comments/18l27c7/adsb_tracking_websites_do_not_show_every_aircraft/Source snippet
RedditADS-B tracking websites DO NOT show every aircraft that...ADS-B tracking websites DO NOT show every aircraft that is flying. Neith...
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Source: medium.com
Title: ADS-B 101
Link: https://medium.com/faa/ads-b-101-ae33179be8f7Source snippet
What It Is, and What It Means to You | by FAA...ADS-B works by having aircraft avionics regularly broadcast position, velocity, and iden...
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Source: flightradar24.com
Link: https://www.flightradar24.com/blog/inside-flightradar24/types-of-gps-jamming/Source snippet
Flightradar24GPS jamming: the benign, the bad, and the scary19 Mar 2024 — Where possible, we track flights experiencing GPS jamming via a...
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Source: flightradar24.com
Title: how flightradar24 uses mlat to counter gps jamming
Link: https://www.flightradar24.com/blog/aviation-explainer-series/how-flightradar24-uses-mlat-to-counter-gps-jamming/Source snippet
Flightradar24How Flightradar24 uses MLAT to counter GPS jamming30 Jun 2025 — Flightradar24 uses Multilateration (MLAT), which allows us t...
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Source: flightradar24.com
Title: Live Flight Tracker
Link: https://www.flightradar24.com/Source snippet
Flightradar24: Live Flight Tracker - Real-Time Flight Tracker...Flightradar24 is the best live flight tracker that shows air traffic in...
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Source: forum.flightradar24.com
Link: https://forum.flightradar24.com/forum/radar-forums/flightradar24-feeding-data-to-flightradar24/12109-not-picking-up-mode-s/page3Source snippet
picking up mode S19 Feb 2019 — There are extended Mode S messages, which transmit ADS-B information, but not every Mode S transponder is...
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Source: flightradar24.com
Title: how does fr24 track aircraft
Link: https://www.flightradar24.com/blog/inside-flightradar24/how-does-fr24-track-aircraft/Source snippet
How does Flightradar24 track aircraft?4 Apr 2024 — By measuring the time it takes to receive the signal from aircraft with an older Mode...
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Source: Wikipedia
Title: [Flight tracking]({{ ‘flight-tracking/’ | relative_url }})
Link: https://en.wikipedia.org/wiki/Flight_trackingSource snippet
Flight tracking - WikipediaMultilateration (MLAT) - Flightradar24...
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/Flightradar24Source snippet
Flightradar24Flightradar24 is a Swedish Internet-based service that shows real-time aircraft flight tracking information on a map. It...
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Source: reddit.com
Link: https://www.reddit.com/r/ADSBexchange/comments/nnrp2w/adsb_flight_track_dumps/Source snippet
ADSB flight track dumps?: r/ADSBexchangeHey y'all, is there a resource anywhere I could download a dump of historical flight tracks? As...
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Source: reddit.com
Link: https://www.reddit.com/r/flying/comments/gop52j/adsb_privacy/Source snippet
ADS-B Privacy: r/flyingWe're being advised that ADS-B exposes us to outside trackers and our privacy could be compromised. FWIW, we've r...
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Source: reddit.com
Link: https://www.reddit.com/r/RTLSDR/comments/nq1hwi/how_can_an_airplane_be_located_through_mlat_by/Source snippet
nes have 'ADS-B' as their signal source, but for some airplanes...
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Source: reddit.com
Link: https://www.reddit.com/r/flightradar24/ -
Source: reddit.com
Link: https://www.reddit.com/r/flightradar24/comments/18vxdal/how_are_flights_with_only_mode_s_being_tracked/Source snippet
How are flights with only mode S being trackedMLAT requires four or more Flightradar24 receivers in a region to receive a signal from the...
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Source: mode-s.org
Link: https://mode-s.org/1090mhz/content/ads-b/1-basics.htmlSource snippet
3. ADS-B basicsAvailability and transmission rate; Surface position, 5–8, 0.2 Hz; Airborne position, 9–18, 20–22, -; Airborne velocity...
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Source: faa.gov
Link: https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afx/afs/afs400/afs410/ads-bSource snippet
Federal Aviation AdministrationAutomatic Dependent Surveillance - Broadcast (ADS-B)29 Sept 2025 — ADS-B Out works by broadcasting informa...
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Source: faa.gov
Title: ins outs
Link: https://www.faa.gov/air_traffic/technology/equipadsb/capabilities/ins_outsSource snippet
Federal Aviation AdministrationIns and Outs7 Feb 2023 — ADS-B Out works by broadcasting information about an aircraft's GPS location, alt...
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Source: adsbexchange.com
Link: https://www.adsbexchange.com/api/aircraft/v2/docsSource snippet
ADS-B ExchangeADSB Exchange API DocumentationThe ADSB Exchange API provides real-time access to live global flight data, enabling retriev...
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Title: 3000117422 how does flightradar24 work
Link: https://support.fr24.com/support/solutions/articles/3000117422-how-does-flightradar24-work-Source snippet
Flightradar24 Support centerHow does Flightradar24 work?Sep 29, 2022 — By measuring the time it takes to receive the signal from aircraft...
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Source: faa.gov
Link: [https://www.faa.gov/pilotsSource snippet
Federal Aviation AdministrationLimiting Aircraft Data Displayed (LADD)1 May 2025 — The LADD program provides aircraft owners the ability...
Published: May 2025
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Source: faa.gov
Link: https://www.faa.gov/air_traffic/technology/equipadsb/privacySource snippet
Federal Aviation AdministrationADS-B Privacy22 Mar 2025 — The FAA acknowledges the desire of some operators to limit the availability of...
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Source: aviospace.org
Title: real time aircraft tracking network
Link: https://aviospace.org/real-time-aircraft-tracking-network/Source snippet
ADSBExchange And The Rise Of Unfiltered Aircraft Tracking26 May 2026 — ADSBexchange's policy of showing all aircraft without filtering ha...
Published: May 2026
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Source: adsbexchange.com
Link: https://www.adsbexchange.com/Source snippet
ADS-B ExchangeADS-B Exchange supports legitimate use cases across aviation safety, investigations, journalism, humanitarian research, and...
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Source: globe.adsbexchange.com
Link: https://globe.adsbexchange.com/Source snippet
Historic track labels: UTC. Smaller wind labels. Label units. Darker Colors. Dark Mode. Dim...Read more...
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Source: adsbexchange.com
Link: https://www.adsbexchange.com/data-products/Source snippet
Data ProductsLive and historical aircraft data for tracking, monitoring, and analysis, delivered via API and data feeds. Live data. The m...
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Source: instagram.com
Link: https://www.instagram.com/flightradar24/Source snippet
Follow us here for a behind the scenes look at the aviation industry. Follow.Read more...
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Source: faa.gov
Link: https://www.faa.gov/air_traffic/technology/adsb/faqSource snippet
ADS-B FAQ3 Mar 2025 — ADS-B also provides greater coverage since ground stations are so much easier to place than radar. Remote areas wit...
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Source: adsbx.discourse.group
Link: https://adsbx.discourse.group/t/multilateration-mlat-how-it-works-and-why-you-should-care/325Source snippet
Multilateration (MLAT) - How it Works, and Why You Should...15 Feb 2024 — It works by measuring the time difference of arrival of an air...
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Link: https://x.com/flightradar24Source snippet
s | FAQ: fr24.com/faq |...Read more...
Additional References
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Source: cfinotebook.net
Link: https://www.cfinotebook.net/notebook/avionics-and-instruments/automatic-dependent-surveillance-broadcastSource snippet
Automatic Dependent Surveillance BroadcastADS-B broadcasts once per second with the aircrafts position, velocity, identification, and oth...
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Source: facebook.com
Link: https://www.facebook.com/asianchronicle/posts/us-air-force-warns-of-opsec-threat-from-online-flight-trackinga-us-air-force-off/1527817099352705/Source snippet
US Air Force Warns of OPSEC Threat From Online Flight...ADS-B Filtering & Privacy Regulations – FlightRadar24 automatically filters mili...
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Source: businessaircraftcenter.com
Link: https://www.businessaircraftcenter.com/articles/ads-b-next-generation-technology-faa-mandate-update-art0417.htmSource snippet
Understanding ADS-B and the FAA MandateA plane with the proper ADS-B aircraft avionics will regularly broadcast position, velocity, and i...
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Source: spire.com
Link: https://spire.com/blog/aviation/understanding-multilateration-mlat-for-more-precise-aircraft-positioning-free-from-interference/Source snippet
Understanding multilateration (MLAT) for more precise...27 Mar 2025 — Multilateration (MLAT) is a method that determines the location or...
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Source: twz.com
Title: congress has made fully obscuring aircraft ownership information a reality
Link: https://www.twz.com/news-features/congress-has-made-fully-obscuring-aircraft-ownership-information-a-realitySource snippet
Congress Has Made Fully Obscuring Aircraft Ownership...17 May 2024 — The FAA re-authorization bill will make it harder to learn who owns...
Published: May 2024
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Source: youtube.com
Link: https://www.youtube.com/watch?v=KahiBjBmgrc -
Source: youtube.com
Link: https://www.youtube.com/watch?v=SfKCwQcsQA0Source snippet
How does multilateration (MLAT) work?mlat requires four receivers in a particular region to receive a signal emitted by an aircraft...
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Source: jetstreamlaw.com
Title: how to block your aircraft tail number from public tracking
Link: https://jetstreamlaw.com/how-to-block-your-aircraft-tail-number-from-public-tracking/Source snippet
20 Jun 2025 — The FAA now has two programs that enable aircraft owners to block or limit access to their ADS-B data: the Limiting Aircraf...
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Source: rtx.com
Link: https://www.rtx.com/collinsaerospace/what-we-do/industries/business-aviation/flight-deck/adsbSource snippet
, and identification, to ground stations and other aircraft every second.Read more...
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Source: superiorskies.org
Title: Compared to traditional radar, which updates every 5
Link: https://superiorskies.org/learn/adsb-technologySource snippet
ADS-B Technology: How We Track Aircraft Over Your...ADS-B-equipped aircraft broadcast their position, altitude, speed, and identificatio...
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