Originally Posted by mr_matt

FAA has interpreted this now. "Mutually agreeable" has morphed into this:

See, e.g., 14 CFR 91.127(a),
91.129(a). Operations within restricted areas designated in part 73 would be prohibited
without permission from the using or controlling agency. Accordingly, as part of the
requirements for model aircraft operations within 5 miles of an airport set forth in section
336(a)(4) of P.L. 112-95, the FAA would expect modelers operating model aircraft in
airspace covered by §§ 91.126 through 91.135 and part 73 to obtain authorization from
air traffic control prior to operating.


EDIT: §§ 91.126 covers Class G airspace