A RAM inlet header, RIH, comprising: a body through which RAM air flows from an inlet toward a heat exchanger; a slotted air nozzle arranged along a wall of the body to direct cooled air into flows of the RAM air and toward the heat exchanger; the slotted air nozzle comprising: a first nozzle wall, which is extendable in a first direction from the wall of the body and which is formed to define a slot extending above and along a plane of the wall; and a second nozzle wall displaced, at the plane of the wall, aft from the first nozzle wall relative to a predominant direction of the RAM air flows through the body and being curvi-linearly extendable toward a distal edge of the first nozzle wall from the wall of the body, wherein the body has a curvature parallel to the plane of the wall, the wall is formed to define holes and the RIH further comprises: a manifold disposed at an exterior of the body and configured to distribute the cooled air to each of the one or more slotted air nozzles via the holes; and a tubular body to transport the cooled air to an intake of the manifold, the RIH being characterised in that: a predominant flow direction of the cooled air leaving the or each slotted air nozzle opposes a predominant flow direction of the cooled air in the tubular body. a body through which RAM air flows from an inlet toward a heat exchanger; a slotted air nozzle arranged along a wall of the body to direct cooled air into flows of the RAM air and toward the heat exchanger; the slotted air nozzle comprising: a first nozzle wall, which is extendable in a first direction from the wall of the body and which is formed to define a slot extending above and along a plane of the wall; and a second nozzle wall displaced, at the plane of the wall, aft from the first nozzle wall relative to a predominant direction of the RAM air flows through the body and being curvi-linearly extendable toward a distal edge of the first nozzle wall from the wall of the body, wherein the body has a curvature parallel to the plane of the wall, the wall is formed to define holes and the RIH further comprises: a manifold disposed at an exterior of the body and configured to distribute the cooled air to each of the one or more slotted air nozzles via the holes; and a tubular body to transport the cooled air to an intake of the manifold, the RIH being characterised in that: a predominant flow direction of the cooled air leaving the or each slotted air nozzle opposes a predominant flow direction of the cooled air in the tubular body. a first nozzle wall, which is extendable in a first direction from the wall of the body and which is formed to define a slot extending above and along a plane of the wall; and a second nozzle wall displaced, at the plane of the wall, aft from the first nozzle wall relative to a predominant direction of the RAM air flows through the body and being curvi-linearly extendable toward a distal edge of the first nozzle wall from the wall of the body, wherein the body has a curvature parallel to the plane of the wall, the wall is formed to define holes and the RIH further comprises: a manifold disposed at an exterior of the body and configured to distribute the cooled air to each of the one or more slotted air nozzles via the holes; and a tubular body to transport the cooled air to an intake of the manifold, the RIH being characterised in that: a predominant flow direction of the cooled air leaving the or each slotted air nozzle opposes a predominant flow direction of the cooled air in the tubular body. a manifold disposed at an exterior of the body and configured to distribute the cooled air to each of the one or more slotted air nozzles via the holes; and a tubular body to transport the cooled air to an intake of the manifold, the RIH being characterised in that: a predominant flow direction of the cooled air leaving the or each slotted air nozzle opposes a predominant flow direction of the cooled air in the tubular body.