Blog
Notes on what is in the sky
How the technology behind flight tracking actually works, what the symbols and codes mean, and the occasional thing we find while building the app. Written to be correct first and interesting second (usually both).
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Build your own ADS-B feeder: hardware, antenna siting, and what to expect
The map is several thousand private rooftops, and it has a hole in it wherever nobody has bothered. What the parts actually are, why antenna height beats money, what the first week looks like, and how feeding the network earns Pro at no charge.
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What GPS jamming looks like from the air
Nobody switches off the satellites. Somebody switches on a transmitter. Why the GPS signal is so easy to drown out, how spoofing differs from jamming, and how one small number in every ADS-B broadcast turns thousands of airliners into an accidental worldwide sensor network.
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How to read a VFR sectional chart
Blue means towered and magenta means it isn't, and from that one rule the rest of the chart unravels. Airspace line styles, airport data blocks, the fraction-like altitude pairs, maximum elevation figures, obstacles, airways and special use airspace.
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What squawk 7700 means, and what it doesn't
An emergency squawk is a request for priority, not a prediction of an accident. What a transponder code is, what happens on the ground the instant 7700 appears, why most of them end with a normal landing, and how to behave when your phone lights up.
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How ADS-B works: what aircraft broadcast, and how anyone can hear it
There is no leaked feed behind flight tracking. Aircraft announce their own position, unencrypted, twice a second. The two radio links, what is inside a message, why the altitude isn't the height, how far a rooftop antenna can hear, and what multilateration fills in.
Elsewhere on the site
- What "unfiltered" flight tracking actually means: LADD, Privacy ICAO Addresses, and where the filtering really happens
- Everything the app does
- Frequently asked questions
- The live map on the web · the GNSS interference map
