An aircraft including an emergency power system , the aircraft having one or more thrust producing gas turbine engine(s) and one or more auxiliary power unit(s), each gas turbine engine having a low pressure spool and a high pressure spool and the emergency power system being for use in the event of an emergency comprising all thrust-producing gas turbine engine(s) and auxiliary power unit(s) of the aircraft failing to operate normally, the emergency power system comprising: an emergency electrical generator configured to be coupled to the low pressure spool during an emergency for generating emergency electrical power; one or more electrical power sources in addition to the auxiliary power unit(s) of the aircraft ; a plurality of electrical loads electrically connected to the emergency electrical generator and the one or more additional electrical power sources; aircraft sensors (96A-96G) for providing data regarding emergency electrical power availability and emergency electrical power demand, wherein the aircraft sensors include current sensors for sensing current generated by each of the emergency electrical generator and the one or more additional electrical power sources, and current sensors for sensing current demand by each of the plurality of electrical loads; and a controller for controlling the emergency electrical generator, wherein the controller is configured to determine emergency electrical power demand and emergency electrical power availability based upon data from the aircraft sensors; wherein the controller is configured to develop an energy extraction plan to increase total energy extracted from a windmilling fan attached to the low pressure spool over an anticipated duration of the emergency based upon the emergency electrical power demand and the emergency electrical power availability, and wherein the controller is configured to control the emergency electrical generator according to the energy extraction plan. an emergency electrical generator configured to be coupled to the low pressure spool during an emergency for generating emergency electrical power; one or more electrical power sources in addition to the auxiliary power unit(s) of the aircraft ; a plurality of electrical loads electrically connected to the emergency electrical generator and the one or more additional electrical power sources; aircraft sensors (96A-96G) for providing data regarding emergency electrical power availability and emergency electrical power demand, wherein the aircraft sensors include current sensors for sensing current generated by each of the emergency electrical generator and the one or more additional electrical power sources, and current sensors for sensing current demand by each of the plurality of electrical loads; and a controller for controlling the emergency electrical generator, wherein the controller is configured to determine emergency electrical power demand and emergency electrical power availability based upon data from the aircraft sensors; wherein the controller is configured to develop an energy extraction plan to increase total energy extracted from a windmilling fan attached to the low pressure spool over an anticipated duration of the emergency based upon the emergency electrical power demand and the emergency electrical power availability, and wherein the controller is configured to control the emergency electrical generator according to the energy extraction plan. <EOS>