Air Traffic Controller meets Flight Instructor on a Flat Earth - SW43

I was a FAA Certified Radar Air Traffic Controller at NAS Brunswick which was a TRACON facility and airport. At night I would get board and set my scope to max 350 miles. I turned it down to watch Boston traffic and Warning areas (no fly zones). Well according to the globe equation I saw airplanes at 81,000 ft. Problem? They squawk their airspeed/altitude and etc... So the Earth can’t curve like they say. Granted I wa