CVFR clearance & IFR weather response
CVFR (Controlled VFR): VFR flight in Class B under ATC clearance. File a flight plan and obtain clearance before entering (TC AIM RAC 5.6).
Clearance timing:
- Not normally issued before takeoff, unless the control zone itself is Class B airspace.
- Otherwise normally issued once position is reported at the last 1 000 ft of altitude below the base of Class B (or before entering laterally); the report confirms the radio works.
Other rules:
- No clearance: VFR aircraft may enter Class B only under a Minister authorization, granted when in the public interest and not likely to affect aviation safety (CAR 601.07(1)-(2)).
- Outside Class B: ATC does not provide separation. Keep vigilant watch for traffic, even under CVFR.
- Clearance contains the phrase "MAINTAIN (altitude) VFR."
IFR weather: CVFR clearance uses IFR-type procedures but does not authorize entering actual IFR weather. Avoid it.
Response to IFR weather (CAR 601.07(3)), by location, not ranked:
| Location | Response |
|---|---|
| Control zone | Request special VFR (only option) |
| Elsewhere in Class B | Request amended clearance keeping VFR weather conditions, or IFR clearance if valid instrument rating and aircraft IFR-equipped (TC AIM RAC 5.6(b)). Two options, no preference |
Neither option available:
- Stay in VFR weather conditions at all times.
- Leave Class B airspace horizontally or by descending (not climbing).
- Control zone: land at the aerodrome the zone is based on.
- Tell ATC what you did as soon as possible.
Trap: expecting clearance before takeoff (normally issued in flight at the Class B boundary, unless the control zone is Class B); escape from IFR weather is horizontal or descending, never climbing. CVFR clearance only borrows IFR-style procedures.
References
- TC AIM RAC 5.6
- CAR 601.07(1)-(2)
- CAR 601.07(3)