<strong>Semicircular Cruising Level System (ICAO)
The cruising levels, or, in case of cruise climb, the range of levels, to be observed when required are as follows:
• Magnetic track, or in polar areas at latitudes higher than 70 degrees and within such extensions to those areas as may be prescribed by the appropriate ATS authorities, grid tracks as determined by a network of lines parallel to the Greenwich Meridian superimposed on a polar stereographic chart in which the direction towards the North Pole is employed as the Grid North.
• Exceptions from semicircular cruising level system are stated on the basis of regional air navigation agreements, from 090 to 269 degrees and from 270 to 089 degrees are prescribed to accommodate predominant traffic directions and appropriate transition procedures to be associated therewith are specified.
Semicircular Cruising Level System (ICAO)
<a href="http://flightcrewguide.com/wp-content/uploads/2013/09/Semicircular-Cruising-Level-System-ICAO.png"><img src="http://flightcrewguide.com/wp-content/uploads/2013/09/Semicircular-Cruising-Level-System-ICAO-300×204.png" alt="Semicircular Cruising Level System (ICAO)" width="300" height="204" class="alignnone size-medium wp-image-433" /></a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/altitude-regulations/" title="Altitude Regulations">Altitude Regulations</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/altimeter-setting-2/" title="Altimeter Setting">Altimeter Setting</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/transition-altitude/" title="Transition Altitude">Transition Altitude</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/transition-level/" title="Transition Level">Transition Level</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/altimeter-setting/" title="System of Flight Levels">System of Flight Levels</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/cruising-levels/" title="Cruising Levels">Cruising Levels</a>
<a href="http://flightcrewguide.com/wiki/rules-regulations/semicircular-cruising-level-system-icao/" title="Semicircular Cruising Level System (ICAO)">Semicircular Cruising Level System (ICAO)</a>
<a href="http://flightcrewguide.com/wiki/inflight/cruising-levels-applicable-rvsm-airspace/" title="Cruising Levels Applicable in RVSM Airspace">Cruising Levels Applicable in RVSM Airspace</a>