Originally Posted by
macoz
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/b5c85ae8e38df676862571da00529da4/$FILE/AC%2091.21-1B.pdf
This appears to cover the subject.
M - You nailed it, and I'm glad you found it. It seems to prove the negative.
Section 7A says the FCC has a rule about being Airborne and that the FAA supports it (but doesn't say they have their own regulation).
7B says that the FAA doesn't prohibit on the ground (except when taxiing for departure, it's up to the carrier.
Thanks for finding that.
-SF