Alternating landing lights
 

You guys were very kind with my first query yesterday so here is another.

I travel by train in to London Fenchurch Street and Limehouse station is directly below the final approach into LCY when they are landing in an easterly direction. A short while ago my train was stopped at Limehouse and I watched a small business-type jet approaching LCY.

Now, from where I was sat it appeared that what I think were the landing lights (the white lights on the front of the wing directly next to fuselage) were flashing, or more accurately brightening one side then the other. Not unlike lights at a level crossing except that they didn't go out, they just got brighter then dimmed.

Did I see what I thought I saw, or was I up too late with the laptop the night before :)

Yes, I think you did. Lots of bizjets seem to have this lighting set-up, in my experience it seemed to be mainly US-registered aircraft.

Pulse Light's
 

No you were not seeing things!

Pulse light or wig wags are becoming very popular, the idea is that it makes a landing aircraft easier to see. here in Australia regional airliners have been retro fitting them to aircraft like dash 8's 737's and the like.

It´s not only that the plane will be easier to see, but it is also to avoid Bird Strikes.

Thanks very much guys. The next intelligent question I can think of, I'll be back here :ok:

The device is a Pulselite and it overrides the Landing or Taxi light switches creating the effect you have seen.
It is particularly useful in poor visibility such as haze.
I have this system fitted to my own Cessna 182, 9M-TAR. You'll find a pic on the web, but it wont pulse :)