International Code Flag - Lima L / Quaratine Flag

The quarantine flag, also called the Yellow Jack, is the international signal flag LIMA, this is the official quarantine flag recognized by the World Health Organization (WHO). It is square in shape. Its display is divided into four smaller squares, with two on top and two on the bottom. The smaller squares are alternately yellow and black in color. The flag is flown from a ship that is either arriving in port with known serious health problems or that has been placed under quarantine by the local port authorities.

Once the local authorities have determined that the ship’s health problems have been resolved and removed the quarantine order, the ship may fly the free pratique flag (e.g., the international signal flag QUEBEC), which is solid yellow.