
Flightradar24 – how it works - crunchiebones
https://habr.com/en/post/440596/
======
fergbrain
“Every civilian airliner is equipped with a special device — the so-caller
ADS-B (Automatic Dependent Surveillance-Broadcast) transponder”

Not true actually: in the US, ADS-B isn’t required until January 1, 2020 [1].

Also, FR24 uses radar data in the US (probably because not all aircraft has
ADS-B) [2].

There are also sites, such as ADS-B Exchange [3] that provide _unfiltered_
flight data...very helpful for tracking military flights and such.

[1]
[https://www.faa.gov/nextgen/programs/adsb/faq/#g2](https://www.faa.gov/nextgen/programs/adsb/faq/#g2)

[2] [https://www.flightradar24.com/how-it-
works](https://www.flightradar24.com/how-it-works)

[3] [https://www.adsbexchange.com](https://www.adsbexchange.com)

~~~
jacobreg
Even after 2020 ADS-B out won't be required in much of the airspace in the US.
Only within 30 nautical miles of a class B airport, within the lateral limits
of a class C airport, within class D airspace, and above 10k feet (but not
below 2500 AGL I think). Even then, its only required for aircraft originally
equipped with an alternator and electrical system (except in class B).

Basically, it's optional in most uncontrolled airspace and for older aircraft.

~~~
loeg
In practice, anything that can be described as an "airliner" is a large
commercial aircraft and flies above 10k regularly. Probably required to have
ADS-B.

~~~
jacobreg
Oh whoops, I misread as "airplane"

~~~
AceyMan
AU: Another good example where it'd pay off to use the 'FQDN', _transport
category aircraft_.

------
mtlabs
If you use macOS you might enjoy my app Max Planes [1]. It displays all the
ADS-B data, tracks planes on a MapKit view and allows you to save and replay
logs.

Also I have an open source Mac app [2] to act a network server for the USB
device. It contains a copy of dump1090 with everything statically linked so
you don't need to build anything yourself. Just plug in the dongle and launch
the app. It is codesigned, sandboxed and notorized.

You can also use the prebuilt dump1090 binary included inside the App.

[1] [https://mtlabs.com.au/planes/](https://mtlabs.com.au/planes/)

[2] [https://github.com/mxswd/dump1090-mac-
app](https://github.com/mxswd/dump1090-mac-app)

~~~
robbiet480
Very nice ADS-B viewer for macOS! Quickly got it connected to
dump1090-mutability once I set the bind host to 0.0.0.0 instead of localhost.
I wish planes were differently colored based on certain characteristics, much
like OpenADSB on iOS (the best ADS-B app IMHO)

EDIT: Also, do you support MLAT?

~~~
OpenADSB
I am the author of OpenADSB, thanks for the kind words. Please don't hesitate
to reach out if you have any suggestions or feature requests.

For those that don't know, OpenADSB is an iPhone/iPad app that connects to any
Virtual Radar Server and dump1090 server. ADSBexchange runs on VRS and
dump1090 is the de facto Raspberry Pi ADS-B decoder. OpenADSB is not
affiliated with but uses ADSBexchange as the default datasource.

[https://itunes.apple.com/us/app/openadsb/id1178703539](https://itunes.apple.com/us/app/openadsb/id1178703539)
[http://openadsbapp.com/](http://openadsbapp.com/)

------
diggan
Worth nothing that if you're in a area with poor coverage, Flightradar24 might
be willing to send you a free receiver [https://www.flightradar24.com/add-
coverage](https://www.flightradar24.com/add-coverage)

Page above also have a similar guide to this submission.

I mainly started contributing with data only because you'll be able to get a
free business account with Flightradar24 if you contribute, which gives you
longer history to view, and bunch of more map layers to use.

~~~
vsl
Article did note, at length.

------
dewey
In case you are interested in this kind of things there's also the same for
ships:

[https://www.marinetraffic.com](https://www.marinetraffic.com)

[https://www.vesselfinder.com](https://www.vesselfinder.com)

[https://www.openseamap.org](https://www.openseamap.org)

~~~
notalwayshuman
Aishub is also applicable, they have a great model.

------
RivieraKid
Not a big fan of "data monopolies" like Flightradar24. It's as if
OpenStreetMaps was a private company that capitalizes on being first into the
space and having a community of contributors willing to supply data to a
private company for free. I hope an open data project such as
[https://www.adsbexchange.com/](https://www.adsbexchange.com/) wins in the
long-term.

~~~
coin
Completely agree. FR24, along with FlightAware, Radarbox24 and Plane Finder
has built a business of monetizing free, crowdsourced data. For FR24 there's
been multiple requests by the community to for an API, some willing to pay,
but they've refused every time. I don't understand why people are eager to
feed into those closed network.

ADSB Exchange on the other hand is built with an open premise, runs off
donations, and encourages third-party app and value add to build off their
API.

~~~
chrissnell
There's probably not much stopping FR24 from feeding off of ADSB Exchange.
This happens in the weather world, where data from community-managed CWOP
weather stations ends up in the hands of commercial weather data services, who
normalize the feeds and incorporate them into their forecasting products.

~~~
freeflight
Isn't there some kind of "free to use, but not to commercialize" license the
CWOP people could be releasing their data under?

~~~
djsumdog
That gets into the very tricky idea of "What is commercialization?" If you use
a Creative Commons works that's BY-NC on your blog, but your blog runs ads, is
it now commercial? What if it's funded by Patreon? That's why Wikipedia
doesn't allow NC and the premise behind the Free Culture licenses.

------
usr1106
In Germany receiving ADS-B used to be illegal (I don't think it has changed,
but I did not verify.)

In Finland receiving as such is not illegal, but forwarding the information
is.

In both cases the reasoning is that this information is not directed to the
public. Whether anybody has ever been prosecuted I have no idea.

~~~
remus
That seems very odd. Somewhat similar to putting up a billboard then saying
it's illegal for people to read it, as the billboard wasn't intended for them.

~~~
heavenlyblue
Someone putting a car in the middle of nowhere doesn’t leave it there for
anyone ti pickup.

~~~
upofadown
But it is pretty OK to look at the license plate...

~~~
izacus
Is it also OK for that license plate to be shown to the world together with
its location and time?

------
trishmapow2
Rtl-sdrs are great, probably one of the best accidental discoveries I've seen.
So many things being sent out from 0-1.5GHz that you can sniff. One that I see
often are the unencrypted pagers broadcasting patient details, hotel security
information etc. Then you've also got amateur radio, air traffic control, GSM,
key fobs, weather stations, satellites, all within the reach of anyone with
$15 to spare.

~~~
pard68
I want[ed] to get one but the options are overwhelming. I dislike buying not-
the-best product. I also dislike eBay, which seems to be one of the main
methods of purchasing a setup (have been burned too many times by sellers).

~~~
ronsor
Buy the kit from rtl-sdr.com -- no need to use ebay and they are the best
option for a beginner

~~~
pard68
Thanks! Bought one for myself and a second for my Ham radio enthusiast father.

~~~
trishmapow2
Consider also an FM band-stop filter and an LNA, apparently makes things so
much better. Even with the antenna removed I can still hear FM broadcast,
ruins the whole band. I've just ordered those two, want to test it with NOAA
reception.

------
santix
There's also a community-based ADS-B site:
[https://www.adsbexchange.com/](https://www.adsbexchange.com/)

~~~
sean-duffy
I use [http://360radar.co.uk](http://360radar.co.uk), which is a small site
run by (I think) just one guy, but it has the best coverage hands down for the
UK. It's used extensively by military aircraft enthusiasts in the UK as it'll
usually show some stuff that isn't on adsbexchange, and provides some nice
features such as aerodrome and weather layers in the UI.

------
punnerud
Extra notes: 1) You can share the same data to multiple sites from dump1090,
not just FR24. 2) I see no difference between the $27 and $9 version of SDR. I
can recommend this one: [https://www.dx.com/p/rtl2832u-r820t-mini-dvb-t-dab-
fm-usb-di...](https://www.dx.com/p/rtl2832u-r820t-mini-dvb-t-dab-fm-usb-
digital-tv-dongle-black-2021120) Running on two different computers and
switching between them give the same number of planes spotted. The $9 actually
seems a hint better. 3) I can recommend saving your own data to a
sqlite3-database ([https://github.com/yanofsky/dump1090-stream-
parser](https://github.com/yanofsky/dump1090-stream-parser)). Easy to work
with and under <50MB/month. Fun to write more advanced sql's to count number
of time helicopter take-off, the same plane over your house etc. that FR24
can't give you.

------
amingilani
Perfect timing. I'm just in the process of building my own shortwave listening
station in Lahore, Pakistan — which is definitely a low coverage area on both
services. I was using a RTL-SDR + Pi and a homebrew antenna to cover the 2m
band, so I guess I could run this in parallel. I was looking at volunteer run
air quality monitoring services just this morning!

Just filled their forms. Slightly concerned about running a blackbox on my
network so I'll have to do some isolation, but this'll be a fun contribution.

------
tyingq
Here's someone spoofing a fake aircraft this way:
[https://www.ainonline.com/aviation-news/air-
transport/2012-0...](https://www.ainonline.com/aviation-news/air-
transport/2012-08-21/hackers-faa-disagree-over-ads-b-vulnerability)

~~~
MarcysVonEylau
That presentation is something that interested me in ADS-B in the first place.
Not because I want to spoof airplanes, but because of novelty of this project.

------
natch
Bait and switch app. They convinced me to fork out for the fully paid version,
then switched to a subscription model that froze current features for those
who had supported their work, adding a nag and an implied threat of end of
life. Stay away.

------
mswd
There's also [https://planefinder.net](https://planefinder.net)

~~~
lesmond
Thank you!

Lee (CTO @ Plane Finder)

~~~
citruspi
Hey Lee,

Just took a look at your website, I was looking for some kind of historical
flight data provider.

Clicked on the "Historical Flight Data" link and it just links to a couple
popular flights which in turn link to pages with a few pieces of flight data
visualized/available.

Clicked on the "Commercial Services" link and it details a few commercial
services including "Historical Flight Data" which says

> Looking for historical flight data? Plane Finder historical flight data is
> available in 5 minute or 1 minute intervals dating back to 2011 and is
> delivered as flat files in CSV format.

"Historical Flight Data" isn't clickable, and I don't want to fill out a form
("Contact Us"), so I click on "View Products" which just links me to your
downloadable apps.

Apologies if there's something I'm missing.

I'm trying to get a look at API docs and pricing, and sign up and get started
without having to "contact your team."

------
phkahler
Is there a simple solution to get a basic offline map (OSM maybe) and use a pi
without internet as a radar display at my local non-towered airport?

~~~
_-___________-_
Yes. A cheap DVB-T dongle supported by RTL-SDR along with
[https://github.com/MalcolmRobb/dump1090](https://github.com/MalcolmRobb/dump1090)
or similar will allow this, but bear in mind that something like this should
really not be used in any situation where flight safety depends on it.

~~~
phkahler
That uses a google map which is nice, but I'd prefer something offline.

~~~
_-___________-_
Should be very easy to swap the google map out for something offline. You can
still use the remaining 99% of the tool which does the
receiving/decoding/interpreting of the signals.

------
aw3c2
Is there a site that offers truly open data, as in a download of all their
collected historic data under a open license and without other restrictions
(like having to query an API)?

~~~
coin
Adsbexchange.com

~~~
aw3c2
Not open data :(

> for non-commercial use, all of this data is freely accessible to anyone!

> Any commercial users are required to license the data from ADSBexchange,
> contact here for terms.

Commercial use is a thing very hard to define so I avoid that even for
personal projects (which could be consider advertisements for my commercial
offers).

------
NKosmatos
One of the reasons I love HN!!! Nicely written and informative post, cheap and
practical stuff, lots of interesting links, comments with extra info... I’m so
definitely building a receiver with my spare RPi3.

------
a2tech
Interesting tidbit from the article—apparently flightradar24 doesn’t show
business jets or military planes.

~~~
rootusrootus
I can confirm it does not show the F15s that routinely fly over my house. But
I see business jets all the time, no problem.

~~~
gruturo
Those may be running with their transponder off?

------
bronco21016
I always thought it would be interesting to package all of this up and sell it
to small operators. For example, a flight school could deploy a small scale
RTL-SDR based ADS-B/MLAT system for tracking of their aircraft. The geographic
area required to cover would be relatively small. Perhaps a 50 nm radius
around the base. Of course they could also just fill in the gaps of something
like Flightradar or ADS-B exchange but sometimes it’s nice to own your
infrastructure.

~~~
corford
Flight Aware offer a conceptually similar product (i.e. aimed at small
operators/FBOs that want to track aircraft) but it uses data from their
network rather than needing you to setup your own gear:
[https://www.flightaware.com/commercial/global](https://www.flightaware.com/commercial/global)

For a more DIY approach, there's these two:
[http://www.coaa.co.uk/planeplotter.htm](http://www.coaa.co.uk/planeplotter.htm)
[http://www.virtualradarserver.co.uk/Default.aspx](http://www.virtualradarserver.co.uk/Default.aspx)

------
sylvinus
Relevant talk on getting data live from the sky with Node:
[https://www.dotconferences.com/2017/12/thomas-watson-
getting...](https://www.dotconferences.com/2017/12/thomas-watson-getting-data-
from-the-sky)

------
hnburnsy
Flightview also offers an enterprise account for those running an ADS-B ground
station and reporting it with their software.

[https://flightaware.com/adsb/piaware/build](https://flightaware.com/adsb/piaware/build)

------
zeristor
Someone put ADS-B on a satellite a few years ago, it looks like this has been
done more recently as well:

[https://www.radarbox24.com/blog/space-based-
ads-b](https://www.radarbox24.com/blog/space-based-ads-b)

~~~
antirez
AFAIK at least in Europe we are exactly in the process of moving ADS-B
receivers in satellites in a large scale fashion to replace the current system
based on ground units. I was talking with a control tower worker a few days
ago and this is what he said, additionally a few months ago as the author of
dump1090 I was approached by the company he mentioned that tried to hire me.
So it looks like it's true.

------
dalore
Blog post could have included a link to
[https://www.flightradar24.com/](https://www.flightradar24.com/) at least in
the first paragraph. Can't find any link in the post at all.

------
chrisu
Similar open source thing exists for gliders:
[https://www.glidernet.org](https://www.glidernet.org) It uses flarm data,
which is received by many enthusiasts. Has been on a rise the last few years

------
alkonaut
I’m assuming there is more to it than just the radio data? In FR you can see
planes everywhere, including thousands of miles off shore.

My guess is that FR24 just looks up the flight path from the flight number,
and then once an airplane goes “off the radar” it just assumes it goes the
shortest/great circle path towards its destination airport - at which point it
will again be in a “known” spot? If this is how it’s done then one should see
lots of planes approaching e.g the US east coast suddenly “shift” from their
estimate position to their transponder positions, as they are picked up by
receivers.

~~~
chrisseaton
But you can see for yourself aeroplanes far over the ocean clearly not
following a great circle route, presumably avoiding weather patterns.

~~~
alkonaut
Interesting. So how does that work in FR24? If there was a service to get this
data over long distances, then all these short range receivers would be
unnecessary. So something is missing in “how does FR24 work” when it comes to
that data.

~~~
speeq
Probably satellite ADS-B receivers like from:
[https://en.wikipedia.org/wiki/Aireon](https://en.wikipedia.org/wiki/Aireon)

~~~
alkonaut
If that's what happens - does that mean that suddenly FR24 won't need all this
data crowdsourcing?

------
neop1x
Flightradar24 has a nice interface and apps but it is CENSORED. Not all
airplanes transmitting ADS-B are visible there.

Fortunately there is
[https://www.adsbexchange.com](https://www.adsbexchange.com) which offers
unfiltered data. You can set up a receiver so that it runs dump1090 separately
and forwards it to both using Beast protocol. You can also participate in
adsbexchange M-LAT.

------
wetpaws
Glad to see english version of the habr slowly getting traction.

~~~
cpv
Good improvement on them. They had interesting articles from time to time,
from various domains (security, gamedev, DYI, management, work-life balance,
work migration, science, etc). Opening to the international audience can only
be beneficial for them, and the audience.

------
saul_goodman
In North America ADS-B is pretty rare except on the coasts where international
flights pass through more frequently. If you are not on the coast and look at
the logs of your flightradar24 receiver you will see that 99% of the traffic
are MLAT rf direction finding logs from mode-S transmissions with no GPS data
used. But it's still easier to call it an "ADS-B" receiver because no one
knows that MLAT is.

------
jalgos_eminator
I started checking Flightradar24 after seeing a few planes circle above my
office building one day. Never knew that transponder data was so accessible!

~~~
Ayesh
You'll be surprised how much data you can easily grab out of thin air, if you
probe the right frequency.

~~~
danso
Reminds me of this DIY article:
[http://jeremybmerrill.com/blog/2016/01/flyover.html](http://jeremybmerrill.com/blog/2016/01/flyover.html)

HN thread here:
[https://news.ycombinator.com/item?id=10969447](https://news.ycombinator.com/item?id=10969447)

------
omegant
They surely get data from other sources too. You can track planes flying
across the ocean, where they get that data from?

~~~
sorenjan
Satellites, radar, interpolation up to 120 minutes, and receivers on islands.

[https://www.flightradar24.com/blog/the-evolution-of-
flightra...](https://www.flightradar24.com/blog/the-evolution-of-
flightradar24-coverage/)

[https://www.flightradar24.com/blog/over-the-
ocean-24-hours-o...](https://www.flightradar24.com/blog/over-the-
ocean-24-hours-of-transatlantic-flight/)

[https://www.flightradar24.com/blog/tracking-flights-with-
sat...](https://www.flightradar24.com/blog/tracking-flights-with-satellite-
based-ads-b-receivers/)

~~~
omegant
Thanks!

------
cm2187
And what do they do above oceans? Interpolate? Or are there fallback sources
of flights positions?

~~~
treahauet
This article suggests that positions are estimated when the aircraft isn’t in
a coverage area. [https://thepointsguy.com/2017/09/how-flight-tracking-
sites-w...](https://thepointsguy.com/2017/09/how-flight-tracking-sites-work/)

It’s also worth noting that FlightAware has partnered with Aireon (owned by
Iridium according to Wikipedia) to put ADSB receivers on satelites that were
launched with Iridum’s NEXT satelite constellation in low-earth orbit. Sounds
like that data is not yet included in the free data FlightAware provides on
its website, but is available commercially.
[https://flightaware.com/commercial/aireon](https://flightaware.com/commercial/aireon)

------
samstave
You know what would be a fun experiment with this:

Would be to specifially watch all the planes that fly in and out of a large
notable event; such as the superbowl, or davos, g-20 summit etc - and see
where all thise private jets come from to get to that event...

~~~
jeromegv
That exists! [https://www.flightradar24.com/blog/watch-the-massive-
exodus-...](https://www.flightradar24.com/blog/watch-the-massive-exodus-of-
private-jets-after-the-super-bowl/)

------
barrystaes
Does something like flightradar24 exist for trains?

The only API i found exclude all freight trains. (Netherlands)
[https://spoorkaart.mwnn.nl/](https://spoorkaart.mwnn.nl/)

------
lostsock
See also the other article currently on the front page of HN re Space Based
ADS-B:
[https://news.ycombinator.com/item?id=19187745](https://news.ycombinator.com/item?id=19187745)

------
tyingq
It updates position and transmits once per second. I wonder if that makes it
useful as a homing signal for a missile. Or perhaps the position resolution
isn't close enough for that?

~~~
loeg
GPS isn't really precise enough for that and targeting civilian aircraft is
easy anyway; this isn't much of an additional attack vector, IMO.

~~~
tyingq
I suppose the benefit of knowing where everything is a security plus. Watching
9/11 documentaries, it was surprising how many aircraft the controllers
couldn't account for.

(Though this does seem spoofable.)

------
theNJR
I don’t know why, but I’m going to set up a station. Just ordered a Pi to
setup pihole, might as well track flights around me too.

------
MarcysVonEylau
It's worth pointing out that you can get a free ADS-B receiver from sites like
Flightradar24 or Flightaware.

The hardware is often proprietary, but they must allow you to re-purpouse the
data received by the antenna (it's public domain).

~~~
LancerSykera
The article goes over this.

~~~
MarcysVonEylau
I'm really not a carefull reader...

------
varlogix
Wow! I had no idea this is how they did it. Very cool!

------
ferros
Then how are they not able to find airplanes like mh370...?

~~~
Liquid_Fire
The coverage is not global - there are gaps over the oceans and in remote
areas (as the article states, it mostly requries unobstructed direct line of
sight).

