Abstract: A method of operating a life support system for an aircraft, the system including a plurality of oxygen supply apparatus, each of which in use is operable to supply product gas, which may be pure oxygen or oxygen enriched gas, to a breathing gas supply apparatus, at least one of the oxygen supply apparatus being a main oxygen supply apparatus and the remainder of the oxygen supply apparatus being auxiliary oxygen supply apparatus, the main oxygen supply apparatus being operable independently of the auxiliary oxygen supply apparatus, characterized in that the method includes operating the main oxygen supply apparatus and supplying product gas to each of the auxiliary oxygen supply apparatus.

Abstract: An oxygen generating device to which a gas mixture containing oxygen is fed, and which is operable to separate the gas mixture into oxygen rich and oxygen depleted gas components, the device comprising a first material which when at an elevated temperature at or above a minimum operating temperature, is active to separate the gas mixture into oxygen rich and oxygen depleted gas components wherein a second material is provided which produces a heating effect within the device when an electrical current passes therethrough, to heat the gas mixture at least when the gas mixture is at a temperature below the minimum operating temperature.