Air navigation is navigation while flying. It is used by pilots in aircraft to know their exact position and fond their way. That is important because if they get lost, they can hit a mountain or fly into a dangerous area or not find a place to land. There are generally two types of air navigation depending on weather. In good weather, pilots navigate themselves visually with maps. But when the weather is bad and they do not see the ground, they use special radio navigational instruments or the air traffic controller navigates them. The first kind of navigation is called VFR (visual flight rules) navigation. The second is IFR (instrument flight rules) navigation. 