ESDU 84007 is concerned with the necessary further treatment of data provided by the manufacturer of the total temperature probe to ensure that results obtained using it are correct under flight conditions. The systematic errors in probe temperature recovery treated are those due to radiation, self heating and, in the case of unsteady conditions, lag. Methods are given for deriving true values of total and ambient temperature which include consideration of the effects of both aircraft and probe-generated shock waves. A particular feature is the treatment of the lag response of a probe having two terms in its response equation. A worked example illustrates the evaluation of true total temperature from flight test data recorded in supersonic flight through an area of changing temperature.