ATC surveillance technology
Four ATC surveillance types (COM 7.0):
| Type | How it works | Aircraft role | Cite |
|---|---|---|---|
| Primary radar (PSR) | Position from range and azimuth of transmitted and reflected RF energy | Passive: aircraft transmits nothing | COM 7.1 |
| Secondary radar (SSR) | Range from time between interrogation and airborne transponder reply | Cooperative: needs transponder | COM 7.2 |
| ADS-B | See ads-b lesson | See ads-b lesson | COM 7.3 |
| Multilateration (MLAT) | Ground receivers measure time difference of arrival (TDOA) of transponder replies | Transponder replies | COM 7.4 |
- SSR with no operating transponder: no position.
- SSR with altitude-encoding transponder adds increased range, positive identification, altitude.
- MLAT: ground surveillance of runways, taxiways, apron areas, even in low visibility.
Trap: only PSR is passive. SSR, ADS-B, MLAT need aircraft to transmit; no operating transponder and no ADS-B = invisible to all three.
References
- TC AIM COM 7.0
- TC AIM COM 7.1
- TC AIM COM 7.2
- TC AIM COM 7.3
- TC AIM COM 7.4