Abstract: A gas turbine engine inertial inlet particle separator having anti-icing. The separator has inner and outer walls defining a main inlet channel and splitter walls dividing the main channel into inner and outer branches. At least one of the walls has a surface portion subject to icing and a partition on the separator is closely disposed behind the one wall to define therewith a narrow annular tunnel. An inlet passage ducts hot compressed air from the engine to one end of the narrow tunnel and a discharge passage ducts the hot compressed air from the other end of the tunnel to a discharge, the flow area of the tunnel being less than the flow area of at least one of the discarge and inlet passages so that the tunnel defines a high velocity, enhanced heat transfer segment of a heating air channel consisting of the tunnel and the inlet and discharge passages. Heat conducting bridges extend across the tunnel to further enhance heat transfer to the icing surface portion.