PROJECT 10073 RECORD CARD - 17 August 1956

On August 17, 1956, at 1550Z, an unidentified aerial phenomenon was reported near Spragueville, Maine. The incident involved an airborne radar contact, specifically an APG-42 type radar, which detected an object at a range of 12 miles. The radar return was described as being as large as a formation of two aircraft or one large aircraft. The intercepting aircraft, an F-89-D, attempted to track the object, but the pilot and radar observer reported that the object was never sighted visually, despite the pilot looking for it under good daylight conditions. The object was tracked for approximately three minutes before it disappeared from the radar scope at a range of 4000 yards. The radar observer estimated the object's speed to be over 500 knots. A limited investigation was assigned to Flight 3-G of the 4602d AISS. Initial internal correspondence suggested placing the sighting in an 'unknown' category. However, subsequent analysis by AFOIN-4E1 concluded that the sighting was likely caused by an aircraft or, more probably, an equipment malfunction. The analysis highlighted that the radar operator's scope and the pilot's scope displayed different sets of conditions, which suggested a potential malfunction of the AI radar. The report explicitly ruled out the possibility of a weather balloon, noting that one had been released at the Caribou Weather Station at 1535Z, which did not align with the observation. The final assessment by Colonel Gordon C. Hoffman suggested that the radar return was likely not a material target.