Set of beacon light units, the beacon light units being usable as part of a beacon light system of an aircraft, the set of beacon light units comprising: a right wing tip beacon light unit configured to be mounted to a right wing structure of the aircraft (100, 202), a left wing tip beacon light unit configured to be mounted to a left wing structure of the aircraft (100, 202), a tail beacon light unit configured to be mounted to a tail structure of the aircraft (100, 202), and a ground illumination aircraft light unit (2, 102) with an operating light emission distribution for illuminating a ground area below the aircraft (100, 202), wherein the ground illumination aircraft light unit (2, 102) is configured to be mounted to an underside of an aircraft fuselage, wherein the operating light emission distribution of the ground illumination aircraft light unit (2, 102) includes a straight downward emission direction normal to the ground area and covers a solid angle of illumination around the straight downward emission direction, wherein the solid angle of illumination is at least 1.3 π sr, wherein the ground illumination aircraft light unit (2, 102) is a beacon light unit, having a flashing mode of operation, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit, the tail beacon light unit, and the ground illumination aircraft light unit (2, 102) is configured to emit red light flashes, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit has a respective warning light emission distribution, with the warning light emission distribution of each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit having: a first light emission opening angle of at least 150° in a first cross-sectional plane, and a second light emission opening angle of at most 180° in a second cross-sectional plane orthogonal to the first cross-sectional plane, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit is configured in such a way that it is mountable to the aircraft (100, 202) with the first cross-sectional plane being oriented in a vertical direction and the second cross-sectional plane being oriented in a horizontal direction, and wherein the first light emission opening angle extends at least 75° both above and below the second cross-sectional plane. a right wing tip beacon light unit configured to be mounted to a right wing structure of the aircraft (100, 202), a left wing tip beacon light unit configured to be mounted to a left wing structure of the aircraft (100, 202), a tail beacon light unit configured to be mounted to a tail structure of the aircraft (100, 202), and a ground illumination aircraft light unit (2, 102) with an operating light emission distribution for illuminating a ground area below the aircraft (100, 202), wherein the ground illumination aircraft light unit (2, 102) is configured to be mounted to an underside of an aircraft fuselage, wherein the operating light emission distribution of the ground illumination aircraft light unit (2, 102) includes a straight downward emission direction normal to the ground area and covers a solid angle of illumination around the straight downward emission direction, wherein the solid angle of illumination is at least 1.3 π sr, wherein the ground illumination aircraft light unit (2, 102) is a beacon light unit, having a flashing mode of operation, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit, the tail beacon light unit, and the ground illumination aircraft light unit (2, 102) is configured to emit red light flashes, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit has a respective warning light emission distribution, with the warning light emission distribution of each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit having: a first light emission opening angle of at least 150° in a first cross-sectional plane, and a second light emission opening angle of at most 180° in a second cross-sectional plane orthogonal to the first cross-sectional plane, a first light emission opening angle of at least 150° in a first cross-sectional plane, and a second light emission opening angle of at most 180° in a second cross-sectional plane orthogonal to the first cross-sectional plane, wherein each of the right wing tip beacon light unit, the left wing tip beacon light unit and the tail beacon light unit is configured in such a way that it is mountable to the aircraft (100, 202) with the first cross-sectional plane being oriented in a vertical direction and the second cross-sectional plane being oriented in a horizontal direction, and wherein the first light emission opening angle extends at least 75° both above and below the second cross-sectional plane.