Hex Code starting character


I was wondering if anyone knows why some of the hex codes in the aircraft.json start with the “~” sign. Are those the anonomized flights? Thanks in advance.


ICAO assigns blocks of mode-S codes to countries and then the countries assign mode-S codes to individual transponders/planes. ~ means that the mode-S code is not an ICAO assigned code.
These planes are usually TIS-B.

I think there was an ADSB newsletter about TIS-B and ICAO registrations.


those are aircrafts via mlat where flightaware anonymized the aircraft …


Thanks. Appreciate the help.


I am not sure now based on the feedback from FA. Thanks for the help.


Anonymized MLAT are mapped onto unassigned blocks of ICAO address. Blocks of mode-S that have’t been assigned to a country.

So tom is correct that ~ does include these types of planes.


Appreciate the help again! Just trying to understand the way this all works. Looking forward to making some Skyview customizations next!