Thread by @steffanwatkins

Here's a way you may not have looked at the data #ADSBexchange gives you.

Planes using ADS-B transmit their precise location (lat/lon/alt/speed/etc) but planes using Mode-S need to be geolocated using multilateration (MLAT). like TRIangulation, but with 4 data points (Multi) 🧵

Here is an image (and link) representing *only* planes being geolocated using MLAT. Meaning, 4 or more #ADSBexchange receivers have them in line-of-sight (LOS); 10 of them.

inaccurate.adsbexchange.com/?filterSources…

Here is the same area, showing you what aircraft transmitting Mode-S are not being geolocated, meaning 4 #ADSBexchange receivers do not have these planes in LOS; 81 of them.

inaccurate.adsbexchange.com/?filterSources…

If you're near these (like near around ~200 miles?) the #ADSBexchange network would benefit from your data to geolocate aircraft. Please consider setting up a receiver to improve coverage of the largest unfiltered aircraft transponder receiver network.
adsbexchange.com/how-to-feed/

Worldwide right now:

- 68 aircraft geolocated with multilateration (MLAT)
- 371 aircraft not geolocated (BUT COULD BE), and only a vague idea where their Mode-S is being transmitted from.

Those ~300-400 aircraft are not shown on globe.adsbexchange.com because they have a very inaccurate dot on the map and are not being geolocated because not enough receivers have them in LOS, so they're relegated to inaccurate.adsbexchange.com; hence the name.

To someone watching an aircraft fly past an urban area where there *is* MLAT coverage, because there are a lot of receivers, they would "vanish" when they dip below 3 receivers in line-of-sight.

Some people might think they turned off their transponder. Don't immediately say that, it's likely incorrect. They are much more likely to have flown outside MLAT coverage (away from the LOS of 4+ receivers) making them *seem* like they disappeared.

I meant below 4 (< 4 or <= 3) receivers in LOS and the aircraft will "vanish" from globe.adsbexchange.com, but from the rest of the thread, you probably understood that.

https://twitter.com/steffanwatkins/status/1627510633519349760

.@Tacko77 is right, comparing multilateration with triangulation does mix apples and oranges; no angles are involved, it's all about the different times it takes for the signal to reach (4) ground-based receivers from the aircraft transmitting the signal.

https://twitter.com/steffanwatkins/status/1627592239714009088