Farol da Barra • Aveiro The Farol de Aveiro signal pattern is a white flash every 4 seconds (Fl W 4s). This specific, unique pattern of flashes is used to identify the lighthouse for mariners. Lighthouses on the seaside serve as navigational aids that warn ships of dangers like rocks and shoals, and guide them to safe harbor entrances. They act as visual beacons, providing a warning or a "come this way" signal, and can be identified by their unique shape, colour, or light patterns, which allows