Cruising altitudes (semicircular rule)
In level cruise your altitude depends on the direction you are tracking (CAR 602.34). Splitting east from west keeps opposite traffic at least 1,000 ft apart; VFR then adds 500 ft to the IFR thousands so VFR and IFR on the same track never share an altitude:
| Track | IFR | VFR |
|---|---|---|
| 000–179° (easterly) | odd thousands: 3,000 / 5,000 / 7,000 | odd + 500: 3,500 / 5,500 / 7,500 |
| 180–359° (westerly) | even thousands: 4,000 / 6,000 / 8,000 | even + 500: 4,500 / 6,500 / 8,500 |
- When it binds: VFR only in level cruise above 3,000 ft AGL; IFR in level cruise at every altitude (CAR 602.34(2)). Climbing or descending, neither binds, and ATC may assign something else.
- Goes by your magnetic track (in Southern Domestic Airspace; true track in the Northern Domestic Airspace, CAR 602.34(1)), not your heading, so apply variation first. Track is the actual path you trace over the ground.
- Above 18,000 ft ASL the table switches to flight levels (IFR and CVFR only), so the whole table above is the low-level, below-18,000 part.
Trap: reading the wrong side of the 180° split, or putting the +500 on the wrong rule set (added for VFR, never for IFR).
References
- CARs 602.34