An improved illuminated airfield guidance sign of the type used for marking ground traffic routes on runways and taxiways has a curved face. The sign is capable of withstanding the prescribed wind load tests and at the same time has even illumination across each of its legend panels. The curved legend panels are preferably formed of sheets of acrylic or equivalent substrate with a thickness of about 0.354 inches except at the edges where the edge portion is about 0.220 inches. The edge portion i.e. peripheral flange fits into the grooves or channels along the base and end panels of the frame.