IFR
IFR cruising levels (semicircular rule)
- Track 000°–179° (magnetic): odd flight level/altitude (FL010, FL030, FL050… / 1000, 3000, 5000 ft).
- Track 180°–359° (magnetic): even flight level/altitude (FL020, FL040, FL060… / 2000, 4000, 6000 ft).
- Above the applicable transition altitude, levels are flown and reported as flight levels; at or below it, as altitudes on QNH.
En-route minimum altitude (no published MEA/MOCA)
- Over high terrain or in mountainous areas: at least 2000 ft above the highest obstacle within 8 km of the aircraft's estimated position.
- Elsewhere: at least 1000 ft above the highest obstacle within 8 km of the estimated position.
- Both figures assume normal navigational accuracy for the conditions — add margin if position uncertainty is greater than usual.
Source: SERA.5015 / ICAO Annex 2 – Cruising levels and minimum altitude