On September 4, 1957, four Portugal Air Force pilots claimed to have seen and chased some UFOs. They took off with their bombers aircrafts from the Ota Air Base in Portugal under Captain José Lemos Ferreira leadership (the others pilots were sergeants Alberto Gomes Covas, Salvador Alberto Oliveira e Manuel Neves Marcelino). When they were heading towards the city of Portalegre, Captain Ferreira noticed a light above the horizon and warned the others. The light changed its own sizes a couple of times, first increasing, then shrinking. After several minutes the pilots noticed a small yellow circle getting out of the craft, and 3 more circles appeared later. When the UFOs were near Coruche, the bigger aircraft climbed out of the Earth as the smaller ones disappeared. The bombers landed without any problems and Captain Ferreira declared: "after this, do not come to us with that Venus, weather balloons, aircraft and similar stuff which have been being used as general explanations for almost every case of UFOs".
On September 10, 1990, around 9:30AM and for about 50 minutes, a small "balloon" was seen hovering towards a small football field, on a small village called Alfena in the outskirts of Porto. The object was described as "a small turtle with long legs" with a metallic shine. The people present got scared and a group of construction workers started throwing stones at it, and the object hovered backed away, leaving the site. An amateur photographer took several pictures of the shapeshifting object; the pictures were considered by several experts as real and the witness accounts by the simple folks were not considered hoax.