A method of operating a gas-turbine engine and an electricity generator powered by torque from the gas-turbine engine, the gas-turbine engine having a compressor working line which is a locus of operating points of the engine as the engine is throttled, wherein the method includes: increasing an electrical load on the generator; and until the electrical output of the generator matches the increased electrical load, repeatedly performing the steps of: (i) detecting the compressor working line position of the engine; (ii) determining if a detected compressor working line position is sufficient or insufficient to allow the engine to provide additional torque to power the generator while maintaining engine operation within a predetermined range of acceptable engine operating conditions relative to the detected working line position; (iii) when the determination at step (ii) is that an engine operating condition is insufficient, modifying operational parameters of the engine to adjust a position of the compressor working line to allow the engine to provide the additional torque while maintaining engine operation within the predetermined range of acceptable engine operating conditions; and (iv) increasing an electrical output from the generator by an amount such that the engine provides the additional torque. increasing an electrical load on the generator; and until the electrical output of the generator matches the increased electrical load, repeatedly performing the steps of: (i) detecting the compressor working line position of the engine; (ii) determining if a detected compressor working line position is sufficient or insufficient to allow the engine to provide additional torque to power the generator while maintaining engine operation within a predetermined range of acceptable engine operating conditions relative to the detected working line position; (iii) when the determination at step (ii) is that an engine operating condition is insufficient, modifying operational parameters of the engine to adjust a position of the compressor working line to allow the engine to provide the additional torque while maintaining engine operation within the predetermined range of acceptable engine operating conditions; and (iv) increasing an electrical output from the generator by an amount such that the engine provides the additional torque. (i) detecting the compressor working line position of the engine; (ii) determining if a detected compressor working line position is sufficient or insufficient to allow the engine to provide additional torque to power the generator while maintaining engine operation within a predetermined range of acceptable engine operating conditions relative to the detected working line position; (iii) when the determination at step (ii) is that an engine operating condition is insufficient, modifying operational parameters of the engine to adjust a position of the compressor working line to allow the engine to provide the additional torque while maintaining engine operation within the predetermined range of acceptable engine operating conditions; and (iv) increasing an electrical output from the generator by an amount such that the engine provides the additional torque.