G'day
genius-747 - you may be getting a couple of things mixed up. I'm a bit pressed for time so will be brief (and apologise in advance if this is unclear):
1) Transition Altitude - this relates only to pressure setting for your altimeter subscale. In the UK it is generally 3,000' but in some areas it is 6,000' or some other setting and if non-standard (i.e. where not 3,000') this will be advised either on the approach plate or by ATC via ATIS etc. In the US its 18,000' I believe!
2) Cruising level - In the UK we use the quadrantlal rule, not the ICAO standard semi-circular rule (more's the pity!), but lets not get hung up on that at this stage: lets stick to the semi-circular rule example you have used here for arguments sake. If the rule says "odd + 5" then you set QNH and fly 3,500' or 5,500' or 7,500' or 9,500' etc. as long as below the transition altitude, BUT once you are above the transition level (whatever it may be - whether FL030 or FL180) you fly the equivalent flight levels (i.e. set to 1013.2mB) and fly e.g. FL035, FL055, FL075 or FL095 etc. as appropriate.
Make sense!?
Andy
P.S. Quadrantal rule (when in UK FIRs):
- Mag Track 000-089 - ODD FL
- Mag Track 090-179 - ODD FL + 500'
- Mag Track 180-269 - EVEN FL
- Mag Track 270-359 - EVEN FL + 500'
Also:
- When descending from FL to altitude: vertical position is given as altitude.
- When climbing from altitude to FL: vertical position is given as FL.
I think! 