Aircraft navigation lights are placed in a way similar to that of marine vessels, with a red navigation light located on the left wingtip leading edge and a green light on the right wingtip leading edge. A white navigation light is as far aft as possible on the tail or each wing tip.[3] High-intensity strobe lights are located on the aircraft to aid in collision...
That must be what I was thinking of Alba, lighthouses.
However, the lights on planes don't just flash on and off, do they? Some go flash, flash. Some go flasherty, flash and some go flash, flash flasherty flash. etc.
The link to Trinity House that tells the flash pattern for Uk light houses is out of order at the moment but this link gives the idea
http://www.parks.ca.gov/?page_id=22010