Method of autonomously operating an aircraft lighting system, the aircraft lighting system comprising at least one autonomously operated exterior aircraft light (6, 8, 10, 12, 14, 16, 18, 20, 22), with each of the at least one autonomously operated exterior aircraft light having at least two operating states, the method comprising the steps of: determining a momentary value of at least one of a group of aircraft operation parameters consisting of height above ground, rate of descent, ground speed, and weight on wheels, for each of the at least one autonomously operated exterior aircraft light, selecting a particular operating state from the at least two operating states depending on the momentary value of the at least one of the group of aircraft operation parameters, and controlling each of the at least one autonomously operated exterior aircraft light in accordance with the particular operating state selected, characterised in that the at least one autonomously operated exterior aircraft light comprises at least one normally on exterior light, having a normal on state and an emergency flashing state, the method comprising the steps of: determining the momentary value of the rate of descent, comparing the momentary value of the rate of descent with a predetermined descent rate threshold value, selecting the emergency flashing state for the at least one normally on exterior light, if the momentary value of the rate of descent exceeds the predetermined descent rate threshold value, and controlling the at least one normally on exterior light to emit a flashing light emission pattern in the emergency flashing state, wherein the predetermined descent rate threshold value is between 15.24 m/s (3000 ft/min) and 35.56 m/s (7000 ft/min). determining a momentary value of at least one of a group of aircraft operation parameters consisting of height above ground, rate of descent, ground speed, and weight on wheels, for each of the at least one autonomously operated exterior aircraft light, selecting a particular operating state from the at least two operating states depending on the momentary value of the at least one of the group of aircraft operation parameters, and controlling each of the at least one autonomously operated exterior aircraft light in accordance with the particular operating state selected, characterised in that the at least one autonomously operated exterior aircraft light comprises at least one normally on exterior light, having a normal on state and an emergency flashing state, the method comprising the steps of: determining the momentary value of the rate of descent, comparing the momentary value of the rate of descent with a predetermined descent rate threshold value, selecting the emergency flashing state for the at least one normally on exterior light, if the momentary value of the rate of descent exceeds the predetermined descent rate threshold value, and controlling the at least one normally on exterior light to emit a flashing light emission pattern in the emergency flashing state, determining the momentary value of the rate of descent, comparing the momentary value of the rate of descent with a predetermined descent rate threshold value, selecting the emergency flashing state for the at least one normally on exterior light, if the momentary value of the rate of descent exceeds the predetermined descent rate threshold value, and controlling the at least one normally on exterior light to emit a flashing light emission pattern in the emergency flashing state, wherein the predetermined descent rate threshold value is between 15.24 m/s (3000 ft/min) and 35.56 m/s (7000 ft/min).