Originally Posted by
Silent-AV8R
The difference is that it is an agreed upon operating limitation and is not, in fact, a rule contained in the FARs.
It is a rule in the AMA safety code. I believe it is also a rule in the FAR. And a rule per law. When within 5 miles of an airport there is a 400 foot ceiling that model airplanes and other sUAS must not cross.