What is Multilateration ("MLAT") and why does it matter
What is multilateration? Multilateration is the use of mathematical calculations to derive positions for aircraft that are not yet transmitting their exact position via ADS-B. By using multilateration, or "MLAT" for short, we can determine the positions of many more aircraft than we would otherwise be able to track. (Even with MLAT there are still some aircraft that we cannot currently track but nearly all commercial airline flights are trackable at least via MLAT.)
How does MLAT work? In simple terms, it represents a form of "triangulation" by which data from multiple receivers is combined to infer the aircraft position. Because we need data to be received by at least 4 different sites to perform the MLAT calculations, we need many receivers in a given area to be able to calculate MLAT results. The more receiver sites that we have then the more accurate the calculations become. When you look at MLAT on our coverage map, you will see that MLAT (the yellow area) tends to be mostly in urban areas where there are most likely to be lots of receiver sites.
So, if you want to track more aircraft in your area, enlist your friends to build a PiAware! As a PiAware data feeder, you receive MLAT results (when available) for all aircraft that you receive at your site. If you are viewing your local data on the dump1090 web interface, the rows in the data table shaded blue are MLAT results. You can see if your receiver is MLAT capable by viewing the "Site Information" section of the "My ADS-B" page on flightaware.com.
For those interested in joining the ADS-B community, FlightAware offers step-by-step instructions to build a PiAware Receiver for under $100.
ADS-B hosts located in areas needing additional coverage might be eligible for a FlightFeeder, a free, prebuilt ADS-B receiver.
FlightAware invites you to join the ADS-B network. You'll become part of a community of aviation hobbyists across the globe and start seeing the skies in a totally different way.