Almost every airliner continuously broadcasts its identity, position, altitude and speed over ADS-B. A network of volunteer ground receivers picks those broadcasts up, and this page compares the aircraft in the current snapshot against the point you are standing on. Nothing is inferred from the sound or the shape of the aircraft: the aeroplane is telling you what it is, and we are reading it out.
Why the nearest plane is not always the one you can see
Distance on its own is misleading. An aircraft descending towards an airport 30 km away is much closer to you than one at cruise 45 km away, but the one at cruise may be the one filling your sky. What matters is the angle above the horizon, which is why we show it: 90 degrees is straight up, and anything under about 15 degrees is close to the horizon and easy to miss entirely. We pick the highest-angle aircraft as the one overhead rather than the nearest one.
What you can tell from the altitude
Above roughly 30,000 ft the aircraft is in the cruise and probably not going anywhere near you: it is crossing your sky on the way between two other places. Between 10,000 and 20,000 ft it is climbing out of or descending towards an airport within a couple of hundred kilometres. Below 10,000 ft, with the gear likely down in the last few miles, it is landing close by. Our airport pages show live movements for each field.
When nothing shows up
If what you can see looks unusual, emergency squawk alerts lists any aircraft broadcasting 7700 or 7600 in the same snapshot, and the live statistics page shows how busy the sky is as a whole.
An empty result does not mean an empty sky. Military aircraft usually do not broadcast a usable position, some private operators request filtering, and ADS-B coverage depends on volunteer receivers, so it thins out over oceans, mountains and sparsely populated areas. Our guide on how flight tracking actually works covers what the network can and cannot see.