ESDU 85036 presents as both equations and graphs approximate formulae for converting errors in pitot and static pressure into corrections to height, Mach number and indicated airspeed. The methods give acceptable accuracy for constructing charts or tables of height and speed corrections for flight and operating manuals when pressure errors are not large. Exact methods for correcting speed and height are also included for use when the pressure errors are large, and guidance is included on the correction procedure under non-steady conditions when any of the errors may depend on the height, Mach number or airspeed. A practical worked example illustrates the use of the methods.