ILS Critical Area Holding Position Sign

About the ILS Critical Area Holding Position Sign

A taxiing aircraft or vehicle can distort the localizer or glide slope signal of an instrument landing system. Where ATC needs the ILS critical area kept clear, an ILS holding position sign — white ILS on red — stands beside the ILS holding position marking (the yellow ladder across the taxiway), and pilots hold there when instructed. Like every mandatory sign, its legend is white with a black outline on a red face.