I was travelling from maimi airport on a flight to londons heathrow, we had just ended a cruise and were travelling home, the light as we climbed above the clouds was very pretty and an unusaul cloud formation caught my eye. while looking at the clouds i noticed off to my left and a fair didtance below us an h shaped object which was stationary at the edge of the clouds. as i watched it slowly moved backwards as if retracting into the cover of the clouds. the structure seemed to be tubular but in a h shape as if the h were lying on its back. although the sighting was over very quickly i was taken aback, i knew it could not have been a plane and the shape did not look like any plane or helecopter i had ever seen. when i told my wife she thought i was kidding, and even now i dont think she believes me. i took some photos of the clouds that had vaught my eye in the first place on my wifes phone, unfortunately it was a case of closing the barn door after the horse had bolted as it is not on any of them. i watch then for as long as i could to see if it would reappear. sadly it did not. if required i can submit the few shots i took of the cloud formations, although there are no signs of the object/craft on any that i can see.