258.3—Definitions.
As used in this part:
(b)
Carrier means any air carrier or foreign air carrier as defined in 49 U.S.C. 40102(2) or 49 U.S.C. 40102(21), respectively, that engages directly in scheduled passenger air transportation.
(c)
Change-of-gauge service means a service that requires a change of aircraft en route but has only a single flight number.