In the example here of the speaker on a pole, a speaker mounted on a ten foot pole, ten feet from a six foot cameraman would appear to line up with an object at over 100 feet 100 yards away, roughly. Numbers done in my head using old money. As you don't know the height of the camera, the height of the speaker or the horizontal distance between any of the three objects, you can't do any sums to calculate the height of the aircraft. Get it?
That you had to explain that speaks volumes about what basis for understanding you are dealing with.
I disagree. The fact that he bothered to explain it to the regulars on a Military forum leads me to conclude that he believes that he has a monopoly on wisdom.