An aircraft light
assembly comprises a light apparatus configured to be supported in a space on the body of an aircraft. The apparatus has one or more light emitting diodes (13) generating visible light and an outer structure overlying the LEDs. The outer structure includes a
light transmission portion through which visible light from the LEDs can pass, and a metallic portion with an outer surface exposed to the external
airflow. A heat-transmitting connection thermally links the LEDs to the metallic portion so that heat from the LEDs flows to the outer surface and is dissipated to the external
airflow. The light
assembly is configured to be secured in a conventional socket for an incandescent
navigation light bulb and to receive the
electrical current supplied thereto by the aircraft electrical
system. Civilian applications of the unit have only visible LEDs. When the unit is for a military aircraft, it has electric circuitry connected with a visible
light source and an IR
light source, and the electric circuitry is configured to process the input current from the socket and based thereon operate in either a visible mode or covert IR mode. Where the current is in one electrical state, such as for example a certain
voltage, the electric circuit sends power only to the visible
light source. When the current is in a different electrical state, e.g., a different
voltage level, the circuitry sends power only to the IR source, and no visible light is emitted. Different input current voltages or characteristics are also used to cause the IR emitter to flash in various patterns that can be programmed into the unit. All control may be accomplished over a
single pair of wires, as in existing systems that do not have IR mode capability. To
upgrade existing aircraft, light source units a shaped to fit in the apertures for existing lenses over incandescent navigational fixtures.