ESDU 88006 gives a simple method, based on a correlation of established measurements made for a range of propeller and turbo-jet and turbo-fan powered aircraft, for predicting approximately the drag increment in flight with one or more engines inoperative (including the drag of the failed engine(s)). The derivation of the parameters used in that non-dimensional presentation is also explained. The alternative method of summing the various component contributions to the drag in asymmetric flight is also considered and methods of estimating some of them are provided together with a list of sources of data for the others. The force and moment equations used to determine equilibrium flight conditions are given for use with either estimated or wind-tunnel aerodynamic data and an example of their application to a transport aeroplane is included. There is also a detailed discussion of alternative ways in which an aircraft may be flown in steady straight flight with thrust or other airframe asymmetries.