There are two ways of flying an aircraft: visual flight – direct and intuitive – and instrumental flight, which is much more technical.
In visual flight conditions, the terrain, cities, roads, etc… give us clear indications of our position. This is the mode practised in Sport Aviation, and in fact with good visibility and at low altitude, a simple road map could be enough to guide us safely. But what happens when the flight takes place in conditions of low or no visibility, over clouds, at night, over the ocean…? In these cases, instrument flight must be used. For this, both the aircraft and the pilot must be qualified.