47 CFR 95.23 - Mobile station description.
(a) A mobile station is one or more units which transmit while moving or during temporary stops at unspecified points.
(b) A mobile station unit may transmit from any point within or over any areas where radio services are regulated by the FCC except where additional considerations apply.
(c) A mobile station unit may transmit from an aircraft or ship, with the captain's permission, which is:
(1) Within or over any area where radio services are regulated by the FCC except where additional restrictions apply; and
(2) On or over international waters, if the unit is transmitting from an aircraft or ship of United States registry.