Planes near me

What leaves your browser, exactly

Asking "what is flying near me" normally means handing a server your precise coordinates and trusting it to forget them. We would rather not be trusted, so this page is built to make that trust unnecessary.

Your browser gives this page a latitude and longitude. Before anything is sent anywhere, that position is rounded to the nearest quarter of a degree and a box is drawn half a degree either side of the rounded point. Only the corners of that box are sent. A quarter of a degree of latitude is about 27 km, so the request that reaches our server describes a large rectangle that everyone in your area shares, and it is identical whether you are at one end of your town or the other. The box itself is roughly 110 km tall, and its width shrinks the further you are from the equator, because lines of longitude converge toward the poles.

The exact position stays in the page and is used for one thing: working out how far each aircraft is from you and in which direction. That arithmetic happens on your device. The distances in the list above were never calculated by us and could not be, because we do not have the number they are calculated from.

The map frame is centred on the rounded point as well, so the map is not a back door either. There is no analytics script on this page, no third-party request of any kind, and no cookie. The privacy policy says the same thing at greater length, and the app it describes works the same way.

Why some aircraft overhead are not on this list

The list is built from ADS-B, which is a broadcast the aircraft makes about itself. That has a very specific set of failure modes, and none of them mean anything is broken.

Not everything is equipped. Gliders, balloons, aircraft with no electrical system and plenty of older light aircraft operating outside controlled airspace can legally fly with no ADS-B at all, and a great many do. This is by far the most common reason an aircraft you can plainly see is not on the screen.

Some of it is on the other frequency. In the United States, light aircraft may use a second link at 978 MHz instead of the worldwide one at 1090 MHz. A receiver listening to one cannot hear the other, so a busy general aviation field can look strangely empty.

Reception is line of sight. The signal does not bend around hills or over the horizon. A receiver on a rooftop can follow an airliner two hundred miles away and miss a helicopter three miles away that happens to be behind a ridge. If you are in a valley, or a long way from any of the volunteers who run receivers, the low and slow traffic near you is the first thing to disappear.

Nothing here is filtered. What we do not do is remove aircraft on purpose. Military traffic, aircraft enrolled in the FAA's LADD privacy programme and aircraft flying under a temporary address are all shown exactly like anything else, which is not true of every tracker.

How to read what you see

Altitude is pressure altitude: what the aircraft's air data system reads with a standard pressure setting, not its height above the ground beneath it. At cruise that is exactly what everyone wants, because every aircraft shares the same reference. Close to the ground it is why a figure here may not match what the crew sees, and it is emphatically not a measure of how far above your roof something is.

Ground speed is speed across the earth, not through the air. On a windy day two aircraft at the same level flying opposite directions can differ by two hundred knots without either flying any faster than the other.

Track is the direction the aircraft is moving over the ground, which is not where its nose is pointing whenever there is a crosswind. An aircraft tracking due north in a strong westerly is flying noticeably left of that.

The callsign is what the crew typed in for this leg, so it changes from flight to flight. The registration and the 24-bit hex address belong to the airframe and do not. When the two disagree, believe the registration. How ADS-B works goes through all of this properly, including where the data comes from in the first place.

No location, or would rather not share it

Entirely reasonable, and the button is not required. Every airport page below carries a live map and a current movement list that is written into the page before it reaches you, so it works with location off, permission denied and JavaScript disabled.