Abstract: A gas turbine engine fuel control system comprises a microprocessor based control unit programmed to calculate the total fuel requirement to achieve a demanded engine speed on the basis of a steady state fuel requirement plus an additional overfuelling requirement. The overfuelling element is calculated in accordance with the lowest of a number of limiting variables which ensure continued engine integrity and safety and a minimum level to prevent engine flame-out and in which all variables and datums are related to an equivalent engine speed or rate of change of engine speed. The steady state fuel element is likewise calculated using a theoretical engine model based on engine acceleration characteristics. The overall system confers highly accurate control of engine speed and acceleration and enables the use of a simple fuel metering valve, in which fuel flow is directly proportional to valve position.