At an isolated location three witnesses saw a huge bird-like creature apparently perched on top of a flat hill. They decided to approach to obtain a better look when the creature took off. They described it as bigger that a 747 (!) resembling an intangible shadow. They were able to see it had split feathers on its wings and on its tail, a predatory beak, no eyes were visible. It flew over the valley counterclockwise and then it just vanished. (The legendary Thunderbird?)

Google map of this location.