For example in Finland you would likely be violating the radio secrecy laws by merely listening unless you're actively involved in aviation (e.g. flying a plane or sitting in a tower)
In all EU countries you would be violating the GDPR if you stored this data without a lawful basis. (If you're wondering what constitutes "lawful basis", here's a helpful tool https://ico.org.uk/for-organisations/gdpr-resources/lawful-b...)
> I doubt the EU courts would argue any other way otherwise we'd need to criminalize tracking of UPS trucks and the like
Why would the GDPR prevent UPS from tracking their own trucks? How is this even remotely related to what we're discussing here?