Red and green are used for normal vector rescaling - see PluginsAndObjects for more info. Blue is used to increase the strobing time (1.0 means flash once per second). Alpha is used to provide an offset to the strobing time.
RGB color is set to white. Alpha is set to brightness or 0 for off.
This light turns off when runway lights are inop or airport lights are off (daytime VFR).
The object param provides an additional phase offset.
The strobe light modulates its brightness based on the angle the user looks at it -- it will go dim if viewed too far off angle above, below, left or right. The RG components rescale the normal. The "direction" of this light is always along the Z axis (subject to animation).
This light strobes at a rate controlled by the color and the object. (The offset in alpha lets you create two lights in the same object with different flash times.)