Strange Object at 38,000 Feet over Ireland

The sighting accord on 1 May 2017 while flying over Ireland en route to Orlando, Florida from Manchester, United Kingdom. The flight number was Condor Flight MT 2604 owned by Thomas Cook Airlines. The object was observed while cruising at 38,000 ft. The object emitted a strange black trail and tended to change shapes. I have to say when I say the object I was a bit stunned because I did not know what it was. I appear to be the only witness to the sighting. The object eventually turned and flew out of sight.