A frangible guy wire of an airport mast, which breaks on impact without presenting a hazard or causing critical damage to the object impacting with it. The main part of the length of the guy wire consists of a tube or tubular profile made of composite material, the proportions of the dimensions and materials of which have been selected in such a way that in the event of impact, the tube (4) or tubular profile will break by fracturing, that is, by breaking into pieces. The wall thickness of the tube or tubular profile is selected to be so thin that the desired fracturing is achieved.