Schweizer,
Actually, that's not exactly correct. Currently the use of model aircraft in the US is covered by the FAA Advisory Circular 91-57. Here is what it says about operating RC planes near an existing airport
C. Do not fly model aircraft higher than 400 feet above the surface. When flying aircraft within 3 miles of an airport, notify the airport operator,or when an air traffic facility is located at the airport, notify the control tower, or flight service station.
The full AC can be seen here:
http://rgl.faa.gov/Regulatory_and_Gu...AC/ac91-57.pdf
The FAA is in the process of looking at new rules governing the use of RC planes, but as of right now there is nothing new in place yet. Until that happens we are still following the guidelines set forth in FAA AC 91-57.
There are many clubs in the US that actually fly at existing full scale airports, or within 3 miles of it, and they have no problems because they simply notify the tower when they are flying. In many cases it's a good setup for the clubs to fly at airports because they usually get better facilities that if they were not at the airport.
Ken