GPS, google earth, celestial navigation, does any FE have an example of them not matching? If they are all correct, the shape of the earth is a geometry problem. They either match RE or FE. If they are not correct, please explain.
To put it another way, does the US Navy know where its ships are? Can they send a ship to Japan and order it mid course to go to Australia? Will it arrive? Will they know the distance and therefor whether they have enough fuel and when it will arrive? Does the US Navy know the shape of the earth?