A blower controller for controlling a blower that supplies a pressurised airflow to an air conditioning pack of an aircraft environmental control system , the blower controller comprising: a pack flow demand adjustment module configured to: receive a pack flow demand signal representative of a desired mass flow rate of an airflow supplied by the air conditioning pack , and a blower condition signal indicative of a condition of an intake airflow received by the blower ; and determine corrected pack flow demand based on the pack flow demand and the blower condition signal ; and a first control signal generator configured to receive the corrected pack flow demand and generate a first control signal to control a first operating parameter of the blower in response to the corrected pack flow demand , and the controller characterized by further comprising a second control signal generator configured to receive the pack flow demand signal and a measured pack flow signal indicative of a measured mass flow rate of an airflow supplied by the air conditioning pack ; compare the pack flow demand signal with the measured pack flow signal ; and generate a second control signal , based on the comparison of the pack flow demand and measured pack flow signal , to control a second operating parameter of the blower . a pack flow demand adjustment module configured to: receive a pack flow demand signal representative of a desired mass flow rate of an airflow supplied by the air conditioning pack , and a blower condition signal indicative of a condition of an intake airflow received by the blower ; and determine corrected pack flow demand based on the pack flow demand and the blower condition signal ; and receive a pack flow demand signal representative of a desired mass flow rate of an airflow supplied by the air conditioning pack , and a blower condition signal indicative of a condition of an intake airflow received by the blower ; and determine corrected pack flow demand based on the pack flow demand and the blower condition signal ; and a first control signal generator configured to receive the corrected pack flow demand and generate a first control signal to control a first operating parameter of the blower in response to the corrected pack flow demand , and the controller characterized by further comprising a second control signal generator configured to receive the pack flow demand signal and a measured pack flow signal indicative of a measured mass flow rate of an airflow supplied by the air conditioning pack ; compare the pack flow demand signal with the measured pack flow signal ; and generate a second control signal , based on the comparison of the pack flow demand and measured pack flow signal , to control a second operating parameter of the blower . receive the pack flow demand signal and a measured pack flow signal indicative of a measured mass flow rate of an airflow supplied by the air conditioning pack ; compare the pack flow demand signal with the measured pack flow signal ; and generate a second control signal , based on the comparison of the pack flow demand and measured pack flow signal , to control a second operating parameter of the blower . <EOS>