ADS-B (Format & Security)
How aircraft frames are built — and secured
What it does
SimpleThe ADS-B receiver let you *read* the messages planes send. This page explains how those messages are *built* — and, importantly, why aviation experts are working to make them safer.
Here's the key idea: today's plane messages don't have a 'signature' proving who really sent them, a bit like a letter with no verified return address. That's fine for a broadcast everyone can hear, but it means the system relies on other checks too. Learning the format helps you understand both how planes share their position and why security upgrades matter — it is not something to broadcast, because interfering with aviation signals is dangerous and illegal.
How it works
SimpleA plane's message packs its ID, height and location into a fixed pattern of bits, with a little math code at the end to catch accidental errors. But that math only catches mistakes — it doesn't prove who sent the message. That's why the ground systems cross-check each plane's reported position against radar and against the timing of the signal arriving at several receivers.
How to use it, step by step
Simple- This is for understanding, not broadcasting — never transmit on aircraft frequencies.
- Learn how a plane message packs ID, height, and position.
- See why a plain error-check isn't the same as a real signature.
- Learn how ground systems cross-check planes to spot anything odd.
Examples
Dissect a DF17 Extended Squitter into its address, type code, payload, and CRC fields.
Understand how time-difference-of-arrival across several ground stations independently checks a reported position.
Reason about what a cryptographic signature would add to ADS-B and why it's non-trivial to deploy.
Tips & things to try
- The receiver is where you actually watch aircraft; this page is about the format and its security.
- CRC catches accidental errors, not forgery — that distinction is the whole security lesson.
- Never transmit on 1090 MHz; the value here is understanding and defence, not operation.