Sim/graphics/animation/lights/airplane strobe light dir
RGB form a 3-part normalized direction vector - see PluginsAndObjects.
A is the strobe index.
Alpha is set to 1 if the strobe light of this index is on and flashing and we are facing it. RGB is set to white.
This light will turn off if strobe lights are not flashing.
This provides an airplane-mounted strobe light with directional properties. X-Plane simulates 4 strobes - normally they all flash together; if a plugin is sequencing strobes, you can use the alpha channel to pick a strobe.