> Totally legal everywhere (except a few rare exceptions, like the UK).
And (after a cursory search) Spain, Portugal, Germany, Austria, maybe France... In other words, legal in some places, illegal in others.
> Text-based ATC communications is done over a different system called CPDLC (FANS-1/A)
ACARS is both an application and a (legacy) lower layer suite of protocols supporting it, but modern ACARS versions and CPDLC can use the same underlying digital channel, as far as I understand (i.e. VDL Mode 2).
As a result, many of these tracking sites can capture both, as well as presumably "legacy/analog" ACARS.
And (after a cursory search) Spain, Portugal, Germany, Austria, maybe France... In other words, legal in some places, illegal in others.
> Text-based ATC communications is done over a different system called CPDLC (FANS-1/A)
ACARS is both an application and a (legacy) lower layer suite of protocols supporting it, but modern ACARS versions and CPDLC can use the same underlying digital channel, as far as I understand (i.e. VDL Mode 2).
As a result, many of these tracking sites can capture both, as well as presumably "legacy/analog" ACARS.