A system for controlling blade tip clearance in a gas turbine engine, the system comprising: an active clearance control system configured to regulate a tip clearance between a blade of the gas turbine engine and a shroud structure radially outward of the blade; a controller in operable communication with the active clearance control system; an operational data source in communication with the controller; and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising: identifying, by the controller, a cruise condition, characterised by: reducing, by the controller, a thrust limit of the gas turbine engine to a de-rated maximum climb thrust, wherein the controller is configured to reduce the thrust limit of the gas turbine engine to the de-rated maximum climb thrust, when the gas turbine engine is operating at the cruise condition; determining, by the controller, a first target tip clearance based on the de-rated maximum climb thrust; commanding, by the controller, the active clearance control system to set the tip clearance to the first target tip clearance; identifying, by the controller, a non-cruise condition; commanding, by the controller, the active clearance control system to set the tip clearance to a second target tip clearance, wherein the second target tip clearance is greater than the first target tip clearance; and increasing, by the controller, the thrust limit of the gas turbine engine to a maximum climb thrust, after commanding the active clearance control system to set the tip clearance to the second target tip clearance. an active clearance control system configured to regulate a tip clearance between a blade of the gas turbine engine and a shroud structure radially outward of the blade; a controller in operable communication with the active clearance control system; an operational data source in communication with the controller; and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising: identifying, by the controller, a cruise condition, characterised by: reducing, by the controller, a thrust limit of the gas turbine engine to a de-rated maximum climb thrust, wherein the controller is configured to reduce the thrust limit of the gas turbine engine to the de-rated maximum climb thrust, when the gas turbine engine is operating at the cruise condition; determining, by the controller, a first target tip clearance based on the de-rated maximum climb thrust; commanding, by the controller, the active clearance control system to set the tip clearance to the first target tip clearance; identifying, by the controller, a non-cruise condition; commanding, by the controller, the active clearance control system to set the tip clearance to a second target tip clearance, wherein the second target tip clearance is greater than the first target tip clearance; and increasing, by the controller, the thrust limit of the gas turbine engine to a maximum climb thrust, after commanding the active clearance control system to set the tip clearance to the second target tip clearance. reducing, by the controller, a thrust limit of the gas turbine engine to a de-rated maximum climb thrust, wherein the controller is configured to reduce the thrust limit of the gas turbine engine to the de-rated maximum climb thrust, when the gas turbine engine is operating at the cruise condition; determining, by the controller, a first target tip clearance based on the de-rated maximum climb thrust; commanding, by the controller, the active clearance control system to set the tip clearance to the first target tip clearance; identifying, by the controller, a non-cruise condition; commanding, by the controller, the active clearance control system to set the tip clearance to a second target tip clearance, wherein the second target tip clearance is greater than the first target tip clearance; and increasing, by the controller, the thrust limit of the gas turbine engine to a maximum climb thrust, after commanding the active clearance control system to set the tip clearance to the second target tip clearance.