There is a clause about flying within 5 miles of an airport. Based on what that says, a letter to an airport informing them that a model aviation flying field exists and where it is would seem to be enough to meet the requirement. Doesn’t imply need for permission. Of course if the airport wanted you to not fly then it might create an issue, but I don’t know how that would be addressed.
The FAA doesn't agree. Its "interpretation" says that if an airport operator says no flying, the FAA will consider flying within five miles of the airport to be endangering the safety of the NAS. So this will give the operator of any backyard airstrip a veto over modeling within five miles of that airstrip. In a lot of places, if you draw a five-mile-radius circle around every airport, there's not much left. In my county, there are thirteen airports. A lot of the discussion of this "rule" seems to assume that airports are places with paved runways. Those are a tiny fraction of all the airports listed on the FAA web site. Does it make sense to allow some farmer with a grass strip that he flies off of three times a year to shut down all modeling activity within five miles of his farm?
The link in your post doesn't work. The text of the FAA "interpretation" is here:
http://www.regulations.gov/#!documen...2014-0396-0001
It's certainly true that the AMA is trying to save the hobby. I wish them well. I also wish that they were doing it more adeptly. By drafting a sloppily worded "exemption" for some modelers, and then getting a senator who had a personal feud with the FAA because of his landing at a closed airport to get that "exemption" put into a law, the AMA seems to have annoyed the FAA, which is retaliating by proposing rules which, if adopted, will have serious effects on most modelers.