Sec. 121.99 - Communication facilities.
(a) Each certificate holder conducting domestic or flag operations must show that a two-way radio communication system or other means of communication approved by the Administrator is available at points that will ensure reliable and rapid communications, under normal operating conditions over the entire route (either direct or via approved point-to-point circuits) between each airplane and the appropriate dispatch office, and between each airplane and the appropriate air traffic control unit, except as specified as §121.351(c).
(b) For the following types of operations, the communications systems between each airplane and the dispatch office must be independent of any system operated by the United States:
(1) All domestic operations;
(2) Flag operations in the 48 contiguous States and the District of Columbia; and
(3) After March 12, 2001, flag operations outside the 48 contiguous States and the District of Columbia.
[Doc. No. 28154, 62 FR 13256, Mar. 19, 1997]