Control zones, extensions & transition areas
| Structure | Purpose | Floor | Top | Radius |
|---|---|---|---|---|
| Control zone (TC AIM RAC 2.7.3) | Keeps IFR aircraft in controlled airspace on approach; lets ATC work mixed VFR/IFR traffic | Surface | 3,000 ft AAE unless specified; military 6,000 ft AAE | Civil tower inside a TCA 7 NM; other civil 5 NM (a few 3 NM); military 10 NM |
| Control area extension (TC AIM RAC 2.7.2) | Controlled airspace around an aerodrome, for IFR traffic: IFR arrival/departure separation at busy aerodromes, or link a control zone to the en route structure | 2,200 ft AGL | Up to but not including 18,000 ft ASL | - |
| Transition area (TC AIM RAC 2.7.5) | Contains IFR operations | 700 ft AGL unless specified | Base of overlying controlled airspace | Normally 15 NM; sized to hold every published instrument approach |
Control zone extras:
- Ceiling wording: CAR 101.01 says AGL; TC AIM RAC 2.7.3 applies AAE.
- Depicted on VFR aeronautical charts and Enroute Low Altitude Charts.
- Classified B, C, D or E by surrounding airspace.
Trap: military zone 10 NM, 6,000 ft AAE, not civil 5 NM, 3,000 ft AAE; extension top excludes 18,000 ft ASL; transition base 700 ft AGL, not extension base 2,200 ft AGL.
References
- CARs 101.01
- TC AIM RAC 2.7.2
- TC AIM RAC 2.7.3
- TC AIM RAC 2.7.5