text: (4) Runway slope-a relatively small cor- 
  rection for ordinary values of runway slope. 
  IMPORTANCE OF HANDBOOK PER- 
  FORMANCE DATA. 
  The performance sec- 
  tion or supplement of the flight handbook con- 
  tains all the operating data for the airplane. 
  For example, all data specific to takeoff, climb, 
  range, endurance, descent and landing are in- 
  cluded in this section. The ordinary use of 
  these data in flying operations is mandatory 
  and great knowledge and familiarity of the air- 
  plane can be gained through study of this 
  material. A complete familiarity of an air- 
  plane’s characteristics can be obtained only 
  through extensive analysis and study of the 
  handbook data. 