AIRCRAFT LANDING LIGHT UNIT, EXTERIOR AIRCRAFT LIGHTING SYSTEM AND METHOD OF OPERATING AN AIRCRAFT LANDING LIGHT UNIT

An aircraft landing light unit (2) includes a plurality of LEDs (10), an optical system (12) associated with the plurality of LEDs (10) for shaping a light output of the aircraft landing light unit (2) for illuminating an aircraft environment, a control unit (16) for controlling the plurality of LEDs (10), and a photo detector (14) arranged for detecting light, emitted by the plurality of LEDs (10), output via the optical system (12) and reflected by atmospheric haze (30), such as clouds, fog, rain and snow, wherein the control unit (16) is coupled to the photo detector (14) and is configured to control the plurality of LEDs (10) on the basis of the light detected by the photo detector (14), thereby adjusting the light output of the aircraft landing light unit (2) to the atmospheric haze.