A portable barricade for use in separating aircraft and ground vehicles comprises a sign panel hanging from a horizontally extending frame member, the frame member and sign panel being supported by first and second pairs of expandable legs. The first and second pairs of legs are supported by two cross braces, the first having a tubular configuration and the second having a planar configuration. The barricade is positioned having its tubular cross brace adjacent the aircraft traffic and the planar cross brace adjacent the ground vehicle traffic. Air flow or exhaust generated by aircraft exert a greater force on the planar cross brace than on the tubular cross brace, tending to maintain the barricade with its legs in an expanded, operational position.