Exterior aircraft navigation light and method of controlling an exterior aircraft navigation light

An exterior aircraft navigation light for an aircraft having a nominal forward flight direction and being able to fly into the nominal forward flight direction as well as into a plurality of further flight directions, such as sideways or backwards,

• wherein the exterior aircraft navigation light has at least one light emission unit and control circuitry coupled to the at least one light emission unit,
• wherein the exterior aircraft navigation light is configured such that each of the at least one light emission unit has a unit-specific light emission direction that has a predefined horizontal angle with respect to the nominal forward flight direction,
• wherein each of the at least one light emission unit comprises:
• a multi-color light source configured to emit red light, white light and green light, and
• an optical system for conditioning the red light, the white light and the green light emitted by the multi-color light source,
• wherein the control circuitry is configured, as a response to a momentary flight direction of the aircraft and the unit-specific light emission direction, to control the multi-color light source such that the respective light emission unit emits one of the red light, the white light and the green light;
• and
• wherein the control circuitry has a control unit comprising a signal input for receiving a flight direction signal indicative of the momentary flight direction, wherein the control unit is configured, as a response to the flight direction signal and the unit-specific light emission direction, to select said one of the red light, the white light and the green light and to control the multi-color light source accordingly for each of the at least one light emission unit;
• wherein the control unit is configured to determine a momentary horizontal emission angle for each of the at least one light emission unit by relating the momentary flight direction to the respective unit-specific light emission direction in a horizontal plane;
• wherein the control unit is configured to select the red light, if the momentary horizontal emission angle is between 0° and 110°, to select the green light, if the momentary horizontal emission angle is between 0° and −110°, and to select the white light otherwise;
• and
• wherein each of the at least one light emission unit has a horizontal light emission opening angle of between 5° and 15° around the unit-specific light emission direction.