Abstract: A translating cowl thrust reverser for a ducted fan gas turbine engine has a fan cowl, the downstream portion of which is translatable axially to open an aperture in the cowl. The aperture has upstream and downstream side-walls and which are curved to deflect fan air flow through the aperture in a forward direction. An annular plate is positioned at the outlet from the aperture and projects into the turbulent flow region on the upstream side-wall to define with the side-wall a recess open to the flow which delays the separation of the flow from the side-wall. This increases the effective area of the outlet and the angle through which the flow is turned thus improving the thrust reverser efficiency to the point at which no cascades are needed in the aperture.