Unknown Traffic Sighted by Alaska Airlines Crew on Onboard Weather Radar

On January 29, 1987, the flight crew of Alaska Airlines Flight 53, a Boeing 737, reported an unidentified radar target while en route from Nome to Anchorage, Alaska. At approximately 1835 AST, while flying at 35,000 feet, the crew observed a strong, bright return on their onboard weather radar at their 12 o'clock position, 25 miles away. Despite the clear weather and unlimited visibility, the crew could not visually identify any lights or objects outside the aircraft. The target appeared to move at an extremely high rate of speed, covering approximately 5 miles per radar sweep (roughly 1 second), until it moved off the scope at 50 miles. The captain initially speculated that the target might be a military aircraft involved in 'war games' in the area. Upon contacting the Anchorage Air Route Traffic Control Center (ARTCC), the crew was informed that there were no other aircraft in their vicinity. The FAA controller subsequently verified with the USAF Alaska Air Command that no military aircraft were operating in that area at the time. Following the incident, the crew was interviewed by FAA inspectors in Anchorage. Subsequent reviews of recorded radar data by FAA personnel, specifically by the Assistant Manager of Automation at the Anchorage ARTCC, yielded no evidence of an aircraft performing as the crew described. The incident was documented through various FAA forms, internal memoranda, and a press release, which noted the sighting of 'unidentified air traffic' on the onboard weather radar system.