SOS has also sometimes been used as a visual distress signal , consisting of three-short\/three-long\/three-short light flashes , or with `` SOS '' spelled out in individual letters , for example , stamped in a snowbank or formed out of logs on a beach . It has also sometimes been used as a visual distress signal , consisting of three short , three long , three short light flashes such as from a survival mirror , or with `` SOS '' spelled out in individual letters , for example , stamped in a snowbank or formed out of logs on a beach .