Wednesday, February 28, 2007

Wall of iPods -- Part Deux

The air was unusually smooth over the north eastern Pacific this morning, which allowed the contrails of preceding jets to stretch over hundreds of miles.

There are a few things worth noting about this picture (besides wondering how many iPods are in it):
  • If you look at the horizon, the contrails appear to curve. That is no illusion. The airplanes fly at constant altitude, so you are seeing the earth's curvature affect the airplanes' flight paths.

  • The airplanes are all flying GPS, so why are their tracks scattered all over the sky? That is an illusion. There was a roughly 30-knot wind on the right beam. To stay on the black line, the airplanes have to crab into the wind. Since the contrails stream directly in the airplanes' six 0'clock, what is apparently cross track error is really the cross wind component multiplied by the time since the jet's passing the camera's vantage point.

  • There are five contrails, plus one lower you can't see because the rising sun had not yet illuminated it.

  • By the way, in case you are still, which presumes you had ever started, wondering how many iPods that is, I worked it out precisely: a bloody lot.


    Blogger Oroborous said...

    Are there still moments when you feel like a Master of the Universe, when the sheer impossibility of what you're doing strikes you ?

    March 01, 2007 12:05 PM  
    Blogger joe shropshire said...

    Nice shot. You've got a pretty good eye, as Curved Earthers go.

    March 01, 2007 12:51 PM  
    Blogger erp said...

    Skipper, did you take this picture? It's fabulous, curved earth indeed. I've never seen that before. May I send it to my brother who's an aviation maven and quite a photographer himself?

    March 02, 2007 6:46 AM  
    Blogger Hey Skipper said...


    ... when the sheer impossibility of what you're doing strikes you ?

    I have been flying for 30 years.

    Even now, it strikes me nearly every time I pilot an airplane, whether at altitude, or the moment it ceases becoming a creature of the ground, or even in the midst of a queue of airplanes waiting for takeoff.

    I must be about the luckiest person alive.


    Yes, I took it.

    I have never seen it before, either. It is rare for contrails to be that persistent, and to be lit in just the right way.

    Ten minutes later the sun rose and the cons vanished. Timing is everything.

    Send your email address to md11driveratcomcastdotnet and I'll shoot you the original.

    March 02, 2007 10:18 PM  

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