When you're observing a conflict zone on a live map, you might notice some aircraft icons have less information than others. They appear on the map, but their speed, altitude, or callsign might be missing. This often means you're not seeing data from ADS-B, but from a different technology called Multilateration, or MLAT. It's a crucial tool for getting a more complete picture of the airspace.
What is Multilateration (MLAT)?
Multilateration is a surveillance method used to determine the position of an aircraft by measuring the time difference it takes for its radio signals to reach multiple ground-based receivers. Unlike ADS-B, where the aircraft broadcasts its own GPS-derived position, MLAT calculates the position externally. Think of it as a form of triangulation, but instead of using angles, it uses timing to pinpoint a location.
How Does MLAT Work?
The process relies on a network of receivers and some clever math. For an aircraft to be tracked with MLAT, it only needs to have a Mode S transponder—standard equipment on most modern aircraft, including many that don't use ADS-B.
- The aircraft's transponder emits a signal in response to radar interrogation or periodically on its own.
- Multiple ground receivers in the vicinity detect this signal.
- Because the receivers are at different distances from the aircraft, the signal arrives at each one at a slightly different time.
- A central server collects these reception times. By comparing the Time Difference of Arrival (TDOA) between at least four receivers, it can calculate the aircraft's position in three dimensions (latitude, longitude, and altitude).
MLAT vs. ADS-B: Key Differences
While both are used for flight tracking, they have distinct advantages and disadvantages, especially for open-source intelligence (OSINT) analysis.
- Coverage: MLAT requires a dense network of at least four receivers with a line of sight to the aircraft. ADS-B can work with just one.
- Accuracy: ADS-B is generally more precise because it uses the aircraft's own high-integrity GPS data. MLAT's accuracy is very good but can be slightly lower due to atmospheric variables and calculation latency.
- Aircraft Compatibility: MLAT's biggest advantage is its ability to track aircraft that do not broadcast ADS-B. This includes many older planes, private jets, and military aircraft that may have disabled ADS-B for operational security.
Why MLAT is Essential for Conflict Monitoring
In conflict and high-tension areas, military, intelligence, and VIP transport aircraft often disable their ADS-B transmitters to reduce their electronic signature. However, they may keep their Mode S transponders active to interact with civilian air traffic control. This is where MLAT becomes invaluable. It allows platforms like the battlemap.online live map to detect and display these aircraft, filling in critical gaps in situational awareness. Observing a flight path calculated via MLAT can reveal military movements or surveillance patterns that would otherwise remain hidden.
Frequently Asked Questions
Is MLAT less accurate than ADS-B?
Yes, generally. ADS-B uses the aircraft's own GPS data, which is more precise. MLAT is an external calculation based on timing, which introduces more variables. However, it is still accurate enough for reliable tracking and analysis.
Why can't all military aircraft be tracked with MLAT?
MLAT depends on receiving a transponder signal. If a military aircraft is flying completely 'dark' with its transponder switched off, or if it is outside the coverage area of a receiver network, it cannot be tracked by this method.
What does TDOA mean?
TDOA stands for Time Difference of Arrival. It's the core principle of MLAT, measuring the tiny time differences for a signal to reach multiple receivers, which allows a server to calculate the source's location. For more definitions, you can visit our glossary of terms.
Where can I learn more about flight tracking?
Our site has a comprehensive FAQ page that covers many common questions about the technologies we use, from ADS-B and MLAT to AIS for ship tracking.