AIRCRAFT PROPULSION SYSTEM

An aircraft propulsion system (5) comprises first and second thrust producing gas turbine engines (10a, 10b). The system comprises a controller (36) configured to determine a required overall propulsion system thrust level, and determine an engine core power level contribution from each aircraft gas turbine engine such that the overall propulsion system produces a minimum overall noise level and meets the required overall propulsion system thrust level. In meeting the minimum overall noise level, at least the first and second gas turbine engines are operated at different engine core power settings.