ADS-B Out
ADS-B (automatic dependent surveillance-broadcast): avionics broadcast own position and identity. ATC tracks aircraft like radar, without radar (TC AIM COM 7.3).
- Automatic: no external trigger, such as an interrogation (unlike a transponder replying to SSR).
- Dependent: works only because avionics broadcast the data.
- Relay: avionics, satellites and/or ground infrastructure relay aircraft parameters to ATC (TC AIM COM 7.3).
- Transmission: on-board equipment compiles flight parameters into the ADS-B message. Sent via Mode S transponder on 1090 MHz extended squitter (1090ES) (TC AIM COM 7.3.1).
- Equipment standard: transponder must carry ADS-B Out meeting RTCA DO-260B or newer (TC AIM COM 7.3.1(a)).
Mandatory airspace (TC AIM COM 7.3.3):
| Airspace | Mandatory since |
|---|---|
| Class A | 10 August 2023 (RAC 2.8.1 also lists ADS-B among required Class A equipment) |
| Class B | 16 May 2024 |
Two identifiers (separate fields):
| Identifier | Used for | Matching rule |
|---|---|---|
| ICAO 24-bit identifier | ATC builds your track from it (TC AIM COM 7.3) | Wired to the airframe; stays the same, not the four-digit squawk code assigned each flight |
| Flight Identification | ATS correlates ADS-B position with the filed flight plan (TC AIM COM 7.3.3) | Flight number or registration, set in avionics or FMS. Must exactly match the Aircraft Identification on the ATS flight plan |
Trap: plain Mode S transponder fails mandate; needs ADS-B Out meeting DO-260B or newer. Flight ID not exactly matching flight plan: ADS-B track fine, plan correlation fails. Squawk code is not the track key.
References
- TC AIM COM 7.3
- TC AIM COM 7.3.1
- TC AIM COM 7.3.3
- TC AIM RAC 2.8.1