1. Mick West

    Mick West Administrator Staff Member

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  2. Trailspotter

    Trailspotter Senior Member

    There is the SSEC archive of all the three WorldView satellites' passes on global and regional maps at
    http://www.ssec.wisc.edu/datacenter/orbit_tracks.html
    https://www.ssec.wisc.edu/datacenter/terra/GLOBAL2017_09_18_261.gif

    Another way is to go to Near Real Time (Orbit Swath) Images at
    https://lance.modaps.eosdis.nasa.gov/realtime/
    These contrails appear in the 11:30 UTC swath:
    https://lance.modaps.eosdis.nasa.go...fl1_143.A2017261113000-2017261113500.250m.jpg

    The flight in question almost certainly was Virgin Atlantic 7B LHR to LAX that passed over the area half an hour earlier:
    Screen Shot 2017-09-19 at 07.52.07.

    There was NEE (70°) high altitude wind that would move its contrail to the observed location:
    https://earth.nullschool.net/#2017/...thographic=-5.83,55.30,3000/loc=-6.925,57.894

    Yes, it's a match between the track and the contrail:
    Screen Shot 2017-09-19 at 11.35.45.
    The aircraft was in the point connected by the yellow line at 10:41 UTC, some 50 minutes before the Terra image was taken. The corresponding point of the contrail is 75 km (47 miles) away downwind. Also, as the satellite was to the East of the contrail, the contrail's projection against the ground would be a few miles further West than its actual position, in a better agreement with the wind speed of 69 km/h.
     
    Last edited: Sep 19, 2017 at 8:15 AM
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  3. Mick West

    Mick West Administrator Staff Member

    Perfect! That's a very consistent wind displacement there. I'd say that's a 100% match.
     
  4. Mick West

    Mick West Administrator Staff Member

    It's heading for a North Atlantic track. The S-Turn could simply be to adjust its position so when it got on the track it was spaced between other planes on that track. S-Turns are a way of doing this without flying in circles or losing too much altitude.

    Or perhaps he made the first turn north a bit early, got re-routed back on his original track, and then made the turn slightly later. Either way, a pretty normal move, leaving an interesting contrail.

    Here's the global context

    20170919-082633-5v4os.

    20170919-082710-f5i84.

    Patrick Roddie told me about it. Although he might also have been pointing at the large amount of contrails there - perhaps not being familiar with North Atlantic Tracks. These are the Sept 19 tracks, probably quite similar to Sept 18.

    upload_2017-9-19_8-31-16.
    Source: http://www.perkins-aviation.ch/weather/NorthAtlantic.html


    Source: https://twitter.com/webbery/status/909816960321388545
     
    Last edited: Sep 19, 2017 at 10:16 AM
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  5. Trailspotter

    Trailspotter Senior Member

    This reminded me an older thread, where somewhat similar zigzag trails were left over California by the SFO bound planes, adjusting their positions while lining up for the arrival:
    https://www.metabunk.org/posts/152765/
    [​IMG]
     
    Last edited by a moderator: Sep 19, 2017 at 10:17 AM
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