In the 4th of July, at about 16:45h, I was in a plane by Avianca company. The plane had just taken off of Guarulhos Airport in S��o Paulo. It was still in ascent route . I was sited by the window of the right side of the plane. I looked out of the window and saw, at the same altitude of my plane and not very far away, a small black object, boomerang-shaped , angular, hard , without any recess or boss, without any visible propeller or turbine, flying parallel to the plane in the opposite direction. He flew in a straight-line path, but in a weird position, like a letter V upside down, with the angle up and the two dashes down. I watched it since it appeared at my window until it disappeared from my view. I was very curious and anxious to find some rational explanation for that. When I got home, I started googling for drone boomerang-shaped, weather balloon boomerang-shaped, and then I found some drawings of UFOs exactly like the one I saw, except for the lights, because the one I saw, during the day, had no lights on.