Air traffic obstacles have to be marked in most cases with red and white colored markings and with aircraft warning lights at night.On larger structures blinking lights are required.A fainter rotating light is on Blosenbergturm, Beromünster, Switzerland.A special method of marking was used at the mast of Deutschlandsender Herzberg/Elster in 1939.On small poles near the mast multiple rotating skybeamers were mounted which illuminated the lens-like structure on the top.