UFO spotted at Chicago's O'Hare Airport?

Over a dozen United Airlines employees reported seeing an "unidentified flying object" on November 7th, hovering over Chicago's O'Hare Airport. All the witnesses say the object was dark gray, and was between 6 feet to 24 feet in diameter with no lights. Described as a rotating Frisbee, the witnesses said the object was in a fixed position in the sky until it darted into the clouds. The Tribune reports that employees were instructed not to speak of the incident.