Refer to figure.
In Non-RVSM airspace, vertical separation above FL290 is 2 000 ft. In RVSM airspace, vertical separation above FL290 is 1 000ft.
The default worldwide semi-circular rule is the East/West orientation of the flight level parity. Cruising levels are based on magnetic track. Magnetic Tracks for IFR flights:
- Your aircraft has track between 0° and 179° => your flight level or altitude must be odd (FL50, FL70, etc.);
- Your aircraft has track between 180° and 359° => your flight level or altitude must be even (FL40, FL60, etc.).
Therefore, as you can see in the attached figure, flying a magnetic track of 230º, the appropriate Flight Levels would be: FL300, FL320, FL340, FL360, FL380, FL400.
“FL310” and "FL390"– Incorrect. These are IFR flight level for easterly (0º to 179º) directions.
"FL420"– Incorrect. RVSM airspace includes flights levels from FL290 to FL410.
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