This report reviews the major aspects of processes that may be used for the determination of in-flight thrust. It includes discussions of basic definitions, analytical and ground-test methods to predict installed thrust of a given propulsion system, and methods to gather data and calculate thrust of the propulsion system during the flight development program of the aircraft. Much of the treatment is necessarily brief due to space limitations. This document and the British Ministry/Industry Drag Analysis Panel (MIDAP) Guide, which SAE Committee E-33 used as a starting point, can be used to understand the processes and limitations involved in the determination of in-flight thrust. (1.1)* Application to a specific in-flight thrust determination program will require the use of many important assumptions not fully developed herein, and these assumptions must be evaluated during the conduct of the program.