It may be that 'we had two dumb controllers at National Airport on those nights'... added that the introduction of digital filters in the 1970s led to a steep decline in UFO sightings on radar."
他认为，也许‘那些晚上在华盛顿国家机场的是两个愚钝的管制员’……（克拉斯）补充说，20世纪70年代数字滤波器的引入使得雷达上观测到的不明飞行物的数量急剧下降。