FAA Federal Aviation Regulations (FARS, 14 CFR)

(a) Subject to applicable immigration laws and regulations, each foreign air carrier shall furnish the ground personnel necessary to provide for two-way voice communication between its aircraft and ground stations, at places where the Administrator finds that voice communication is necessary and that communications cannot be maintained in a language with which ground station operators are familiar.

(b) Each person furnished by a foreign air carrier under paragraph (a) of this section must be able to speak both English and the language necessary to maintain communications with the aircraft concerned, and shall assist ground personnel in directing traffic.