Method of alerting ground personnel that the engines of an aircraft are running by operating a set of aircraft beacon light units (10, 12, 14) of the aircraft, characterized by: emitting first flashes of aviation red light from a right wing tip aircraft beacon light unit, positioned on a right wing tip of the aircraft, the first flashes of aviation red light having a first vertical light emission opening angle of at least 150° in a first vertical cross-sectional plane, extending through the right wing tip aircraft beacon light unit, and a first horizontal light emission opening angle of between 90° and 140° in a horizontal cross-sectional plane of the aircraft, the first light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, emitting second flashes of aviation red light from a left wing tip aircraft beacon light unit, positioned on a left wing tip of the aircraft, the second flashes of aviation red light having a second vertical light emission opening angle of at least 150° in a second vertical cross-sectional plane, extending through the left wing tip aircraft beacon light unit, and a second horizontal light emission opening angle of between 90° and 140° in the horizontal cross-sectional plane, the second vertical light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, and emitting third flashes of aviation red light from a tail aircraft beacon light unit, positioned on an aft portion of the aircraft, the third flashes of aviation red light having a third vertical light emission opening angle of at least 150° in a third vertical cross-sectional plane, extending through the tail aircraft beacon light unit, and a third horizontal light emission opening angle of between 100° and 180° in the horizontal cross-sectional plane, the third vertical light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, wherein the first, second, and third horizontal light emission opening angles (20, 22, 24) of the right wing tip aircraft beacon light unit, the left wing tip aircraft beacon light unit, and the tail aircraft beacon light unit add up to at least 360°, such that a 360° illumination in the horizontal plane of the aircraft is possible via the right wing tip aircraft beacon light unit, the left wing tip aircraft beacon light unit, and the tail aircraft beacon light unit. emitting first flashes of aviation red light from a right wing tip aircraft beacon light unit, positioned on a right wing tip of the aircraft, the first flashes of aviation red light having a first vertical light emission opening angle of at least 150° in a first vertical cross-sectional plane, extending through the right wing tip aircraft beacon light unit, and a first horizontal light emission opening angle of between 90° and 140° in a horizontal cross-sectional plane of the aircraft, the first light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, emitting second flashes of aviation red light from a left wing tip aircraft beacon light unit, positioned on a left wing tip of the aircraft, the second flashes of aviation red light having a second vertical light emission opening angle of at least 150° in a second vertical cross-sectional plane, extending through the left wing tip aircraft beacon light unit, and a second horizontal light emission opening angle of between 90° and 140° in the horizontal cross-sectional plane, the second vertical light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, and emitting third flashes of aviation red light from a tail aircraft beacon light unit, positioned on an aft portion of the aircraft, the third flashes of aviation red light having a third vertical light emission opening angle of at least 150° in a third vertical cross-sectional plane, extending through the tail aircraft beacon light unit, and a third horizontal light emission opening angle of between 100° and 180° in the horizontal cross-sectional plane, the third vertical light emission opening angle extending at least 75° both above and below the horizontal cross-sectional plane, wherein the first, second, and third horizontal light emission opening angles (20, 22, 24) of the right wing tip aircraft beacon light unit, the left wing tip aircraft beacon light unit, and the tail aircraft beacon light unit add up to at least 360°, such that a 360° illumination in the horizontal plane of the aircraft is possible via the right wing tip aircraft beacon light unit, the left wing tip aircraft beacon light unit, and the tail aircraft beacon light unit.