14 CFR 129.1 - Applicability and definitions.
(1) A permit issued by the U.S. Department of Transportation under 49 U.S.C. 41301 through 41306, or
(2) Other appropriate economic or exemption authority issued by the U.S. Department of Transportation.
(b) Operations of U.S.-registered aircraft solely outside the United States. In addition to the operations specified under paragraph (a) of this section, §§ 129.5, 129.7, 129.9, 129.11, 129.14, 129.20 and 129.24, and subpart B of this part also apply to operations of U.S.-registered aircraft operated solely outside the United States in common carriage by a foreign person or foreign air carrier.
(c) Definitions. For the purpose of this part -
(2) Years in service means the calendar time elapsed since an aircraft was issued its first U.S. or first foreign airworthiness certificate.