Multilateration (MLAT) now available on PiAware!

FlightAware is excited to announce that in addition to ADS-B flight tracking, PiAware (v2.1 and above) now supports live multilateration (MLAT) flight tracking of non-ADS-B aircraft.  By triangulating the Mode S signal from non-ADS-B aircraft, PiAware can now track twice as many aircraft around the world!

Aircraft being tracked with MLAT will be in blue on your local web interface.  If you’re not seeing any blue aircraft, make sure you have the most accurate location and elevation set here on your stats page and also read below about improving coverage.  MLAT flights and stats will soon be available on as well.

For MLAT to work, an aircraft needs to be within line of sight of four PiAware ground stations.  To improve MLAT coverage in your area, you need to recruit friends to setup PiAware so your receivers can work together to track flights!  Please post about this announcement and share the setup link via:

  • Facebook

  • Twitter

  • Emails to friends and family in your area

Please spread the word and help expand MLAT coverage using PiAware!  The more PiAware receivers near you, the more availability of MLAT data.

Thanks for using FlightAware and PiAware!

FlightAware Team

More on MLAT:

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nice! the culmination of a lot of hard work from fa staff and community.

my pi2 is coming in today as well

The initial build of PiAware is still at 2.0.4 on the downloads page, maybe with this big announcement we can get that upgraded to 2.1 so new feeders aren’t having to upgrade immediately after install. Hate to have new feeders come online and their mlat doesn’t work out of the box.

We’ll get a new one posted in the next few days. 2.0.x now gets auto-upgraded within 10 minutes fortunately, but I agree it’s not ideal.

Yeah the hurt comes when an unaware user loads up, thinks they are good to go and plonks it out in the middle of nowhere with enough Internet to feed but painful to upgrade. Most of us here know how to avoid that but we’re targeting the general public. Don’t want any new feeders to get discouraged out of the box when they don’t get immediate gratification :blush:

This is really cool, thank you. One comment is I can’t get the drag and drop the pin for location to work. Tried on a couple of machines and a couple of browsers. Might be my pilot error, but I can’t figure it out. Again tho, really cool and thank you for all the hard work for my fun!

What browsers? Just tested using Chrome and it worked OK.

Silly question from someone who should know better–

I"m running current versions of Dump1090-mutability (1.14) and PiAware (2.0-7). The FlightAware stats page says I have MLAT supported and enabled.

BUT when I connect to the local Pi webpage (e.g. wombat.local:8080) I don’t see pretty blue things indicating MLAT. (This is site 4847 on FlightAware)

My question/suspicion is I’m connecting to the Dump1090-mutability web page on port 8080, and I need to do something to turn that off and instead use a web page generated by PiAware?

(sudo netstat -tulanp shows I’ve got a connection to dump1090-mutability on port 8080 from my desktop box. the only connection for PiAware on the Pi is tcp to FlightAware, with a udp connection from fa-mlat-client to FlightAware)

Yes? How? My apologies – I’ve been spending a lot of time (too much time) trying to save a startup recently…


Bob, I believe only the FA SD-Card version and the development version (v1.15~dev) of Dump1090-Mutability will produce that display.

P.S. see this posting if you’d like to move up to the v1.15~dev version of Dump1090-mutability.

P.P.S. also, do a manual upgrade restart on PiAware from the Control Panel Command Line on your stats page will get you the latest PiAware 2.1-2

You will need piaware 2.1 to receive mlat results.

By default it will feed results to localhost:30004; your dump1090 is probably listening there and will combine the results with other position data.
To be able to distinguish the mlat results you need to either:

  • install the development version of dump1090-mutability, which knows about mlat positions
  • use something that takes a separate data feed e.g. VRS and use piaware-config -mlatResultsFormat to tell piaware/fa-mlat-client to send the results to it.
  • use the FA dump1090 (but that would probably be a backwards step with your setup)

I’ve upgraded and have mlat enabled, but I see no blue aircraft in the dump1090 web view. There are definitely more than four piaware users within range. I’m seeing this in the log file:

[2015-07-16 13:59 EDT] mlat(2136): Input connected to localhost:30005
[2015-07-16 13:59 EDT] mlat(2136): Problem reading receiver messages: Out of range timestamp seen (last 16598787275658, now 653881278132)
[2015-07-16 13:59 EDT] mlat(2136): Ensure that only one receiver is feeding data to this client.
[2015-07-16 13:59 EDT] mlat(2136): A single multilateration client cannot handle data from multiple receivers.
[2015-07-16 13:59 EDT] mlat(2136): Lost connection to localhost:30005
[2015-07-16 13:59 EDT] mlat(2136): Reconnecting in 30.0 seconds

While I do have multiple receivers, they’re located at the same geographic co-ordinates, ± 20 feet. In other words, they’re very close to each other. One faces west, the other south. The feed from both is piped through ModeSMixer2 and then to dump1090 and piAware. PlanePlotter also connects to the ModeSMixer2 feed (on a different port) and passes all the mlat/mu/gu tests on that network. PP is also feeding FlightAware.

Any ideas?


when you say fa dump1090, are you talking about the one linked on the install page? or is there a dump1090 included in the piaware?

This is unfortunately exactly the problem - the mlat client expects data from one receiver only. Even if the receivers are co-located, each receiver produces a different sequence of timestamps with no easy way to distinguish them.

At the moment you’ll need to either run a separate piaware for each receiver, or disable mlat.


or is there a dump1090 included in the piaware?

The FlightAware dump1090 is a separate package to piaware, but both are included on the SD card image if you installed from that.

Trying to update my position but getting the “too far away” error discussed here:

What’s the best way to contact FA about getting my position moved back to AZ now that my piAware and I are back at my normal location after 10 days in Ohio?

Don, on dropping the location pin issue I had. For whatever reason, the “Next” button didn’t appear on Chrome or IE, until I zoomed out a bit. Once I zoomed out, I see the next button and all is good. Just might be my setup, or maybe the popup box isn’t set to appear centered on the screen? Whatever, I’m good and thank you again very much for all you do. Take care. Joe

I’ve noticed that on wide screen monitors the next button is often off the bottom of the page. I just change it to the coordinate mode and submit from there instead when that happens.

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I’ve had to restart PiAware several times during today to bring the display of MLAT data back. Is this something on the server or client side?

I am running dump1090-mutability v1.15~dev and PiAware 2.1-2 on all six sites.

If there’s nothing odd in piaware’s logs, server side. The mlat servers that cover your area are a bit overloaded at the moment so they can be a bit flaky. It should recover on its own though.

Ok, so if I disable one of the receivers (or rewire the network so only one receiver forwards to piAware), I’ll get the mlat aircraft showing up. (I’ve tested by disabling one and it works.) Can I then create another output from dump1090 by using --net-ro-port and have both the ads-b and mlat aircraft positions visible in whichever app I connect to that data stream?