text: While the very peak value of specific range 
  would provide maximum range operation, long 
  range cruise operation 
  is generally recom- 
  mended at some slightly higher airspeed. 
  Most long range cruise operation is conducted 
  at the flight condition which provides 99 per- 
  cent of the absolute maximum specific range. 
  The advantage of such operation is that 1 
  percent of range is traded for 3 to 5 percent 
  higher cruise. velocity. Since the higher cruise 
  speed has a great number of advantages, the 
  small sacrifice of range is a fair bargain. The 
  curves of specific range versus velocity are 
  affected by three principal variables: airplane 
  gross weight, altitude, and the external aero- 
  dynamic configuration of the airplane. These 
  curves are the source of range and endurance 
  operating data and are included in the per- 
  formance section of the flight handbook. 
  
  Thus, the total range is dependent on both 
  the fuel available and the specific range. When 
  range and economy of operation predominate, 
  the pilot must ensure that the airplane will be 
  operated at the recommended long range cruise 
  condition. By this procedure, the airplane 
  will be capable of its,maximum design operat- 
  ing radius or flight distances less than the 
  maximum can be achieved with a maximtim of 
  fuel reserve at the destination. 