File talk:2010-04-06 48 11 zb Mammendorf 0008.jpg

The angles are likely not as sharp as they appear in the the picture: remember that it's a three-dimensional trail and only a two-dimensional picture, so I can't look at it and know exactly the route the airplane took. It does look like the airplane was going straight and then sidestepped and returned to the original heading. Reasons to do such a thing include:

• airplane is arriving at an airport and has just received instructions to align with a different runway than it was originally planning
• avoidance of other traffic

Remember that the contrails move with the air, so the airplane may have been going in a straight line, but another later airplane or random air currents disturbed the air in such a way as to bend the contrails. It's possible too that a configuration change of the airplane, such as retracting flaps, reducing power and raising gear, all of which occur just after takeoff, changed the way the contrail was produced in such a way as to make the pattern you saw.

I don't know which is most likely. -Robyn 18:11, 16 May 2010 (UTC)

Thanks for taking a look at the picture. It may remain a mystery. I saw the plane taking both turns, so I think it was not just wind blowing a part of the contrail somewhere else. From where I was, it looked like turns at the same (cruise?) altitude, but it might as well have been a change to a different flight level. Maybe this plane was faster than another one in front of it and wanted to pass it? --Zb 19:30, 16 May 2010 (UTC)

Yep, or maybe the copilot wanted to take a picture of his house. -Robyn 22:59, 16 May 2010 (UTC)