PART V-OPERATING DATA

               Select the height at which maximum range is available
               at that fuel state.  The distance available includes
               distance covered on the climb but not on the descent.
               (Absolute maximum range is obtained by adding on
               the descent distance, provided that the let-down starts
               at that distance from the destination.)  For short-
               range flights, inspect the sea level block and select the
               height at which the distance to be covered requires the
               least amount of fuel.  This is the best altitude for the
               flight.

         (ii)  In-flight planning
          
               At any stage of the flight, the available range may be
               ascertained by applying the fuel state to the level
               flight range in the particular block.  If an increase in
               range is required, or if a climb has to be made, the
               new available range may be obtained by entering the
               existing altitude block at the appropriate fuel state
               and moving verticaslly downwards within the block
               until the new altitude is reached.  Figures in heavy
               type indicate the best altitude for the maximum
               increase in range.  Above these heights, no further
               increase in range is possible.  If a descent is necessi-
               tated, the new range is shown by moving direct from
               the existing altitude level flight range for the appro-
               priate fuel state to the new altitude level flight range.

     (c)  Cruise data charts

               The cruise data charts show aircraft performance and fuel
               consumption in level flight at various heights and r.p.m.
               
     99.  Endurance
     
          At any altitude, maximum endurance will be obtained by
          flying at the I.A.S. which requires the lowest r.p.m. to
          maintain height.  Increase in altitude gives increase in
          endurance; however, the overall endurance may not be
          improved by climbing above 20,000 ft., except when maxi-
          mum fuel is available, owing to the proportion of fuel used
          on the climb and the descent.  All climbs should be made
          at full power (within jet pipe limitations) and the
          descent made as quickly as practicable.

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