Abstract: An electronic gas turbine fuel control of the slave datum type, i.e. one including a circuit which generates a speed error signal, an electronic integrator which integrates that error signal to produce a speed datum signal and a difference amplifier comparing the speed datum signal with the actual engine speed to produce a fuel error signal, incorporates a surge detection and recovery circuit. For detection the rate of change of the fuel error signal is derived and compared with a reference value varying with engine conditions. For recovery, if the rate of change exceeds the reference value for a predetermined time during acceleration, the speed error signal is caused to go negative for a fixed period to ramp the integrator output downwards, after which acceleration is allowed to recommence.