Cigar-shaped UFO caught since a plane in Poland

On May 26, 2015, a witness was returned home from vacation in plane. When plane was over Kraków (in Poland), this passenger has photographed a cigar-shaped UFO… What is it?

Witness report:

I was returning home from vacation. The plane started to reduce flight. I took a few pictures by my phone because of nice clouds around. I did not see anything special. I did not notice UFO. When I got home I started watching photos I took. Then I have noticed thin line at the picture I have sent you. When I zoomed in at the end of this line I have realized that this is
something unusual.