Flashing Landing Lights
Sorry in advance for this question from a decidedly non-pilot perspective...
I work in Washington, DC, and my daily commute across the 14th street bridge (usually in heavy traffic) gives me plenty of time to take advantage of the great view of the aircraft either taking off or landing at National.
On a couple of occasions in the last year, I've noticed aircraft on approach flashing their landing lights (not just the usual anti-collision ones). Does this signify anything in particular?
By the way, the view of the aircraft when they're landing to the south at National is particularly spectacular from the bridge, especially around sunset. Easily the highlight of my commute. That right-hand turn just before touching down looks like fun...