Hemispheric Cruising Altitudes
Above 3,000 ft AGL, pilots choose a cruising altitude based on magnetic course so opposite-direction traffic is vertically separated. (US rules, below 18,000 ft MSL.)
| Magnetic course | IFR | VFR (above 3,000 ft AGL) |
|---|---|---|
| 0° – 179° (easterly) | Odd thousands (5,000, 7,000…) | Odd thousands + 500 (5,500, 7,500…) |
| 180° – 359° (westerly) | Even thousands (4,000, 6,000…) | Even thousands + 500 (4,500, 6,500…) |
Memory aid: “East is odd, West is even.” At and above FL180 (US), IFR uses standard flight levels; VFR-on-top has its own rules.
Reference only — verify against the current FAA Aeronautical Information Manual (AIM) and regulations before flight. More quick reference.