IFR  EVEN  2,000'  Intervals  begin at  18,000' MSL  VFR or  VFR-ON-TOP  EVEN  2,000'  Intervals  begin at  FL 185  IFR  ODD  2,000'  Intervals  begin at  FL 190  VFR or  VFR-ON-TOP  ODD  2,000'  Intervals  begin at  FL 195  3 5 9 ° M  1 8 0 °  0 °  1 7 9 ° M  18,000' MSL to flight level 290  IFR  EVEN  4,000'  Intervals  begin at  FL 310  VFR or  VFR-ON-TOP  4,000'  Intervals  begin at  FL 320  IFR  4,000'  Intervals  begin at  FL 290  VFR or  VFR-ON-TOP  4,000'  Intervals  begin at  FL 300  3 5 9 ° M  1 8 0 °  0 °  1 7 9 ° M  Flight level 290 and above  IFR  EVEN  thousanGLYPH<df00>s  VFR or  ON-TOP  EVEN  thousanGLYPH<df00>s  plus  500'  IFR  ODD  thousanGLYPH<df00>s  VFR or  ON-TOP  ODD  thousanGLYPH<df00>s  plus  500'  3 5 9 ° M  1 8 0 °  0 °  1 7 9 ° M  Cruising altitudes - U.S.  IFR within controlled airspace as assigned by ATC  For additional symbol information  refer to the chart user’s guide.  VFR above 3000' AGL unless otherwise  authorized by ATC IFR outside controlled  airspace all courses are magnetic  NO VFR FLIGHTS WITHIN  CLASS A AIRSPACE  CRUISING ALTITUDES  IFR within controlled airspace as assigned by ATC  VFR above 3,000' AGL unless otherwise  authorized by ATC IFR outside controlled  airspace all courses are magnetic  Figure 2-66. Cruising altitude or flight level.  IFR Cruising Altitude or Flight Level  2-42  During IFR flight, ATC advises flights periodically of the  current altimeter setting, but it remains the responsibility  of the pilot or flight crew to update altimeter settings in a  timely manner. Altimeter settings and weather information  When operating on an IFR flight plan below 18,000 feet  MSL in accordance with a VFR-on-top clearance, any VFR  cruising altitude appropriate to the direction of flight  between the MEA and 18,000 feet MSL may be selected that  allows the flight to remain in VFR conditions. Any change in  altitude must be reported to ATC, and pilots must comply  with all other IFR reporting procedures. VFR-on-top is not  authorized in Class A airspace. When cruising below 18,000  feet MSL, the altimeter must be adjusted to the current  setting, as reported by a station within 100 NM of your  position. In areas where weather-reporting stations are  more than 100 NM from the route, the altimeter setting of  a station that is closest may be used.  In controlled airspace, pilots must maintain the altitude or  flight level assigned by ATC, although if the ATC clearance  assigns “VFR conditions on-top,” an altitude or flight level as  prescribed by 14 CFR Part 91, § 91.159 must be maintained.  In uncontrolled airspace (except while in a holding pattern  always important, especially when being radar vectored  during a climb into an area with progressively higher MVA  sectors, similar to the concept of MCA. Except where diverse  vector areas have been established, when climbing, pilots  should not be vectored into a sector with a higher MVA  unless at or above the next sector’s MVA. Where lower  MVAs are required in designated mountainous areas to  achieve compatibility with terminal routes or to permit  vectoring to an instrument approach procedure, 1,000 feet  of obstacle clearance may be authorized with the use of  Airport Surveillance Radar (ASR). The MVA provides at least  300 feet above the floor of controlled airspace. The MVA  charts are developed to the maximum radar range. Sectors  provide separation from terrain and obstructions. Each MVA  chart has sectors large enough to accommodate vectoring  of aircraft within the sector at the MVA. [Figure 2-65]  of two minutes or less or while turning) if operating an  aircraft under IFR in level cruising flight, an appropriate  altitude as depicted in the legend of IFR en route high  and low altitude charts must be maintained. [Figure 2-66] 