Let's assume I am flying VFR from A to B.

B is located north-northwest of A, eg. a direct course would yield a magnetic track of, say, 350°(M). However, some legs of my route are northeastwards, before dog-legging northwestwards, eg. 020°(M) then 340°(M).

In that case, how do I apply the semi-circular rule when selecting a flight level? Would I:

  • only consider the location of my destination relatively to my departure, and my route as a whole, and select an even FL+5?
  • select my flight level leg-wise, ie. flying at an odd FL+5 in the northeastwards part of the route, then even FL+5 when adjusting westwards?

1 Answer 1


The selection of a level is based on your aircraft track, so you should always adjust based on the current leg not the overall track of origin to destination.

(Highlighting in the following is mine.)

The VFR rules of flight level and/or altitude selection is the same as IFR ones with adding 500ft to all levels.

The default worldwide semi-circular rule is the East/West orientation of the flight level parity:

  • Your aircraft has track between 0° and 179°, your flight level or altitude must be odd.
  • Your aircraft has track between 180° and 359°, your flight level or altitude must be even

source: https://wiki.ivao.aero/en/home/training/documentation/Semicircular_rules


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .