300NM, according to this FR24 post about their first receiver in Antarctica, at Troll research station. https://www.flightradar24.com/blog/tracking-flights-wit

300NM, according to this FR24 post about their first receiver in Antarctica, at Troll research station. https://www.flightradar24.com/blog/tracking-flights-with-our-first-receiver-in-antarctica/ https://www.flightradar24.com/blog/tracking-flights-with-our...