On the evening of November 23, 1953, Air Defense Command Ground Intercept radar operators at Sault Ste. Marie, Michigan identified an unusual target near the Soo Locks. An F-89C Scorpion jet from Kinross Air Force Base was scrambled to investigate the radar return; the Scorpion was piloted by First Lieutenant Moncla with Second Lieutenant Robert L. Wilson acting as the Scorpion's radar operator. Wilson had a difficult time tracking the object on the Scorpion's radar, so ground radar operators gave Moncla directions towards the object as he flew. Moncla eventually closed in on the object at about 8000 feet in altitude. Ground Control tracked the Scorpion and the unidentified object as two "blips" on the radar screen. The two blips on the radar screen grew closer and closer, until they seemed to merge. Assuming that Moncla had flown either under or over the target, Ground Control anticipated that moments later, the Scorpion and the object would again appear as two separate blips. Donald Keyhoe reported that there was a fear that the two objects had struck one another, but the single blip continued on its previous course. Attempts were made to contact Moncla via radio, but without success. A search and rescue operation by both the USAF and the RCAF was quickly mounted, but failed to find a trace of the plane or the pilots. Weather conditions were a factor in hampering the search. The official USAF Accident Investigation Report states the F-89 was sent to investigate an RCAF C-47 Skytrain which was travelling off course. The F-89 was flying at an elevation of 8000 feet when it merged with the other aircraft, as was expected in an interception. Its IFF signal also disappeared after the two returns merged on the radar scope. Although efforts to contact the crew on radio were unsuccessful, the pilot of another F-89 sent on the search stated in testimony to the accident board that he believed that he had heard a brief radio transmission from the pilot about forty minutes after the plane disappeared. Air Force investigators reported that Moncla may have experienced vertigo and crashed into the lake. The Air Force said that Moncla had been known to experience vertigo from time to time: "Additional leads uncovered during this later course of the investigation indicated that there might be a possibility that Lt. Moncla was subject to attacks of vertigo a little more than the normal degree. Upon pursuing these leads, it was discovered that statements had been made by former members of Lt. Moncla's organization but were not first hand evidence and were regarded as hearsay."