Originally Posted by Top_Gunn

Please point to a statement I have made about the airspace that is even partially wrong. Certainly nobody has pointed to an error in any of those statements yet. (Someone else made a claim about flying over airports which was true only in Class D airspace, but that wasn't me.) I am serious but not particularly concerned about the possibility that the FAA may not use the geographic center of some private airports to measure the five-miles when the rule goes into effect. This isn't something I said after having been "proved" wrong, it's always been my position. I simply don't know what they will do. (They will use the ARP which is the “The approximate geometric center of all usable runway surfaces.” How do I know this you may ask and I will say because of the documents the FAA referenced in their interpretation of SEC 336.) The FAA doesn't even use the geographic center for all purposes involving full-scale aviation. For example, the size of the class D airspace around some towered airports is determined by reference to the location of the ends of the runways; the geographic center just tells them where the center of the circle is and gives pilots a point to measure whether they're close enough to have to contact the tower. CLASS D− Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace will normally be designed to contain the procedures. Arrival extensions for instrument approach procedures may be Class D or Class E airspace. Unless otherwise authorized, each person must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace. No separation services are provided to VFR aircraft. (As you were told it is possible to fly “over” without contact. The same is true for Class B and C airports also.)
I'm sure the FAA determines the geographic center of the airports that go on the sectional charts. I'm not sure that they go to every backyard airstrip and determine their geographic centers. Maybe they do, maybe not. Nobody has even tried to "prove" this. The fact that there are latitudes and longitudes in the FAA's list of airports doesn't show where those figures came from. Major T says they do it by flying over them, which is impossible, (I believe he was referring to FAA Flight Check operations which operates over 30 aircraft of several different types and yes they fly over airports, in some cases as low as 50ft to check runway headings and other measurements.) as you'd have to know the boundaries of an airport to locate its geographic center, (No just the boundries of the runways.) and you can't do that by flying over it. But why would they even bother if it isn't going to be on the sectional charts?