Equipment and Systems
This domain tests the surveillance and automation that underpin radar control, and what you do when that equipment degrades. Questions ask how identification is established, what a safety net does, and which contingency procedure applies.
Surveillance
- PSR uses primary returns only; SSR interrogates the transponder (Mode A identity, Mode C level, Mode S selective address and data link). Monopulse SSR and Mode S give more accurate, less garbled plots.
- ADS-B (1090 MHz extended squitter) broadcasts position from the aircraft; multilateration uses time difference of arrival from multiple receivers.
- Radar identification methods: recognise the position report correlated with a plot, turn the aircraft and observe the turn, or request ident (IDENT). Use the least intrusive valid method.
Separation and vectoring
- 5 NM radar separation normally, 3 NM in designated TMAs where the conditions are met.
- Vectoring requires assigning headings, monitoring track and issuing traffic information; the pilot remains responsible for terrain clearance unless minimum vectoring altitudes are applied.
Automation and safety nets
- Flight data processing generates strips and label data; safety nets include short-term conflict alert, minimum safe altitude warning and approach path monitoring.
- Alerts are warnings requiring immediate assessment, not separation tools. A silenced alert is not a resolved conflict.
Displays and contingency
- Data blocks show identity, level, trend, speed and route; label overlap must be managed deliberately.
- Contingency: radar failure, degraded mode, display freeze, communication failure, or loss of power. Actions typically: confirm the failure, inform the supervisor and adjacent units, revert to procedural separation, limit traffic, and restore service only when the system is verified.
Worked example
A controller's screen freezes with eight aircraft under control. Reasoning: the last known positions are historical and cannot be used for separation. Immediately apply the contingency plan: stop new clearances, inform aircraft and adjacent units, increase spacing or hold traffic, and switch to procedural separation using position reports with the published time minima until the system is restored and verified.
Traps
Using an STCA alert as a separation standard; treating a position report as radar identification; forgetting that ADS-B position quality depends on airborne data; assuming a degraded system is safe because the display still shows targets.