The 1966 Sebring, Florida, report came from NICAP. It is summarized in UFOs: A New Look, and in The UFO Evidence: Vol. II, pp. 128-29. - Dick
Giant Cone Shadows Private Aircraft
James J. O'Connor, private pilot, attorney, and former Army investigator, was flying at 9,500 feet (about 3 km) on September 20, 1966 near Sebring, FL, when at about 10:00 A.M. he saw what first appeared to be a delta-shaped object overhead. Curious, he climbed toward the object, but leveled off at about 10,000 feet due to lack of oxygen equipment. Suddenly the object descended toward his plane and began pacing him, its huge size blocking out the sunlight. It made a "singing" noise like automobile tires on a wet pavement. '
When his plane was completely in the shadow of the object for several minutes, O'Connor became apprehensive. He pulled up his plane, reduced power and stalled out, diving as fast as he could without putting a strain on his plane. He dropped to 3,500 feet (1,050 meters) before looking up again. "That's when I was frightened," he reported. "That thing had not changed size at all, but was still with me and pacing me. It was still as big as a football field."
Briefly O'Connor thought of shooting at the UFO with a .38 Special he kept in the cockpit, but about that time the object appeared to change shape to a wedge, then a thin line. "I realized it was climbing," O'Connor said, "doing a reverse peel-off in a 360 degree turn. We don't have an aircraft that could do this, I think. It was more like the thing was 'falling up.'" He estimated that the object had followed him for 17 minutes.
The sighting was in bright daylight with a clear sky, some light altocirrus clouds high above. When he first noticed the object overhead, O'Connor opened his canopy and looked straight up at it. He was flying visual flight rules (VFR) from Winter Haven to Miami at the time. When the UFO broke off pursuit and climbed away, O'Connor got a view of the underside of a cone, point upward. 59