 When they were told that the object had moved directly behind their plane, they began a sharp turn to try to see the object, but were told by National Airport's radar center that the object had "disappeared" when they began their turn.At the request of the Air Force, the CAA's Technical Development and Evaluation Center did an analysis of the radar sightings.Their conclusion was that "a temperature inversion had been indicated in almost every instance when the unidentified radar targets or visual objects had been reported."