DITY, if we're talking about high level contrails, they are caused by the jet exhaust, specifically the water content, being mixed by wingtip vortices. Hempy, if you were to take another picture 30 secs later you'd see two contrails. Beagle, what you say about pressure drop is true but doesn't much help identify our mystery machine; we're talking tens of thousands of feet over Texas not Honington on a drizzly morning.
Last edited by ShotOne; 30th Mar 2014 at 16:06.