ESDU Perf RT1/0 discusses the application of a graphical presentation of flight measured data to allow determination of aircraft performance at different atmospheric@ aircraft weight and engine speed conditions from those applying at the time of test. It presents the relationships used for thrust@ fuel flow and drag (assuming a parabolic drag law)@ develops the functions used in ESDU Perf RT1/1@ ESDU Perf RT1/2 and ESDU Perf RT1/3 for level speed@ rate of climb@ and range and endurance respectively@ and discusses the assumptions and limitations implicit in their development.