In “My Brush with History” (November) Peter D. Baird writes an amusing story of his experience as an aircraft spotter while he was a grade schooler in Moscow, Idaho, during the early days of the Cold War in the 1950s. The impression one gets is of a slipshod operation.

But my experience in Bismarck, North Dakota, in 1953–54 was more positive. I was a-geologist there in the opening days of the Williston Basin oil boom and was recruited, along with a number of others from my company, to man the Air Force’s “filter center” at night. There we would receive calls from spotters like Mr. Baird, scattered over the state, and in turn we would relay the information to Rapid City Air Force Base.

Trained as an aerial gunner in World War II, I was favorably impressed. The filter center had a large, gridded map of the state. One or more spotters had been recruited for each grid, and when a plane appeared overhead, they would report it to us and we would place a marker on that spotter’s grid to represent it. As other spotters called in we pushed the marker from grid to grid across the map. Virtually every plane that entered our state was reported as it crossed the border, and the reports continued to come in, grid after grid; our coverage was nearly always solid. I developed a great admiration for those farmers and ranchers who conscientiously monitored the cold North Dakota skies night after night.