A method improving acceleration efficiency of a gas generator of a gas turbine by reducing take-up of electric power, during transition phases, to conserve a sufficiently large surge margin for an operating line. The method increases acceleration/deceleration power of the gas generator by adjusting voltage of an electric network onboard the aircraft. After a phase of starting the gas turbine, voltage of the onboard network is adjusted by a voltage set value controlled by determining unballasting/ballasting status of a main electricity generation source of the onboard network. The status-determining is executed according to demand for taking power to be supplied for propulsion of the aircraft. The status-determining is followed by selecting a voltage set value from plural levels according to the determining the unballasting/ballasting status, and applying the selected set value to a control loop of the voltage supplied to the onboard network.