ESDU 77015 gives simple formulae@ derived from an analysis of a wide range of aircraft operating data@ that enable still-air estimates of range@ fuel used@ and time based on cruise performance to be adjusted for the net loss of energy during climb (including acceleration) and during descent (including deceleration). The method@ suitable for project estimates of block distance@ fuel and time@ applies to stages in which climb and descent are not substantial portions of flight. The formulae given for lost range and fuel apply to turbo-prop engined aircraft and to piston engined aircraft for which different formulae are given depending on whether the cruise was calculated using a lean mixture (best economy) or rich mixture (best power). The formulae for lost time depend on the ratio of climb or descent speed to cruise speed.