A3 is the open-category subcategory "fly far from people". It is the home of heavier drones: classes C2, C3 and C4, plus older legacy drones without a class marking, up to 25 kg. A large share of self-built drones and pre-regulation purchases fly under A3 conditions.
The core principle is full separation from people: no uninvolved persons may be present in the flight area, and a minimum distance of 150 m must be kept from residential, commercial, industrial or recreational areas. Flying in A3 requires passing the A1/A3 exam.