A US Air Force pilot witnessed an unidentified flying object while on a classified mission in California. The object, described as a football-sized dark gray cylinder, passed at high speed under the aircraft's wing.

The Air Force pilot came across a close encounter with a 'cylindrical' object that ground control reported as a UFO, the leaked audio reveals.

A leaked recording reveals a USAF pilot on a secret mission encountered a “football-sized” UFO at 20,000 feet over California. The dark gray, cylindrical object passed just 10 feet beneath his wing before vanishing.

The airman revealed the chilling sighting in a leaked audio tape which captured his conversation with air traffic controllers in the skies above Los Angeles while flying a Homeland Security mission