As others have said, it depends on terrain, your antenna, the altitude of the aircraft, etc. But generally, 50-60 miles is pretty easy with almost any setup. I

As others have said, it depends on terrain, your antenna, the altitude of the aircraft, etc. But generally, 50-60 miles is pretty easy with almost any setup. I have an ADS-B antenna mounted on my roof that feeds into a filter and an amp, and I get less than 50 miles in some directions (because of mountains) and more than 150 miles in other directions (over the ocean). Here's a map of my coverage (any altitude), with range rings every 50 miles: https://www.flickr.com/photos/wallofhair/51403416502 https://www.flickr.com/photos/wallofhair/51403416502 My coverage for altitudes up to 10,000 feet: https://www.flickr.com/photos/wallofhair/51404165241 https://www.flickr.com/photos/wallofhair/51404165241 It's radio, so nothing's guaranteed. Those maps show the maximum ranges at which I picked up any aircraft in that direction over a couple months, so they're kind of a best-case, showing when conditions possibly happened to be perfect. I also have a dead zone just around my house, because my gain is configured to prioritize range. Lots of tradeoffs in RF. There's a site (with an impossible-to-remember name) that can predict antenna range for you (it's not obvious how to use it; Try "New panorama", then "Up in the Air"): http://www.heywhatsthat.com/ http://www.heywhatsthat.com/ Here's what it shows for me. The blue ring is 40,000 feet altitude and the orange ring is 10,000 feet altitude: https://www.flickr.com/photos/wallofhair/51404944889 https://www.flickr.com/photos/wallofhair/51404944889