The invention relates to a flush-mounted flashing light for approach guidance of aircraft, having a housing which has a housing pot (10) which can be inserted below ground level (F) and a housing cover (12) which covers this approximately at ground level (F) and having an optical system, which is arranged in the housing for controlled production and directed emission of light flashes, which comprises a light source (20) for production of light flashes and a prism (40) for varying the direction of the beam direction of the light flashes, with at least one light outlet opening (13) being provided in the housing cover (12) for light flashes to emerge from in a predetermined emission direction. The external dimensions as well as the total weight of the flashing light can be reduced considerably because the light source (20) is elongated and designed to emit a light over a length (L) of less than 100 mm, and because a lens (42) for focusing the light which is emitted from the light source (20) is arranged on a light inlet surface (41) of the prism (40).