The performance or operational information section of the airplane's flight handbook contains the operating data for the airplane; that is, the data pertaining to takeoff, climb, range, endurance descent, and landing. The ordinary use of these data in flying operations is mandatory for safe and efficient operation. Considerable knowledge and familiarity of the airplane can be gained through study of this material. Complete familiarity of the airplane's performance characteristics can be obtained only through extensive analysis and study of the complete handbook.

 It must be emphasized that the information and the data furnished in the airplane flight handbooks by the various manufacturers has not always been standardized. Some provide the data in tabular form, while others use graphs. In addition, the performance data may be presented on the basis of standard atmospheric conditions, pressure altitude, or density altitude. Thus, the performance information in airplane operating handbooks has little or no value unless the user recognizes those variations and makes the necessary adjustments.

   To be able to make practical use of the airplane's capabilities and limitations, it is essential to understand the significance of the operational data. The pilot must be cognizant of the basis for the performance data, as well as the meanings of the various terms used in expressing performance capabilities and limitations.

   Since the characteristics of the atmosphere in which the airplane operates has a predominant effect on performance, we should first review some of the dominating factors - pressure and temperature.