Navigation references can come in many forms. For example in the SWPA our aircrews used US generated strip maps for fighter aircraft which gave headings and distance, and visual references. This was because most fighter aircraft had limited navigation equipment (i.e. a compass) For bomber aircraft the navigator used charts produced again by the US along with astro/sun sightings using a sextant, drift sightings, and heading/time calculations. The charts had latitude and longitude markings and with the standard magnetic deviation of the period, all could be used to obtain a fix. One of the major problems were the charts produced relied on very old naval charts developed by early explorers and the Royal Navy (for the SWPA), and these were often out on the actual positions of some islands) As the war progressed, more accurate maps were produced as the result of maritime and aerial surveys.