14 C.F.R. § 121.431 – Applicability.

(a) This subpart:
1. (1) Prescribes crewmember qualifications for all certificate holders except where otherwise specified; and
2. (2) Permits training center personnel authorized under part 142 of this chapter who meet the requirements of §§ 121.411 through 121.414 to provide training, testing, and checking under contract or other arrangement to those persons subject to the requirements of this subpart.
(b) For the purpose of this subpart, the airplane groups and terms and definitions prescribed in § 121.400 and the following definitions apply:
Consolidation is the process by which a person through practice and practical experience increases proficiency in newly acquired knowledge and skills.
Line operating flight time is flight time performed in operations under this part.
Operating cycle is a complete flight segment consisting of a takeoff, climb, enroute portion, descent, and a landing.

[Docket 10171, 36 FR 12284, June 30, 1971, as amended by Amdt. 121-250, 60 FR 65949, Dec. 20, 1995; Amdt. 121-248, 60 FR 20869, Apr. 27, 1995; Amdt. 121-250, 60 FR 65949, Dec. 20, 1995; Amdt. 121-259, 61 FR 34561, July 2, 1996; Amdt. 121-263, 62 FR 13791, Mar. 21, 1997; Docket FAA-2010-0100, Amdt. 121-365B, 81 FR 2, Jan. 4, 2016; Amdt. 121-382, 85 FR 10925, Feb. 25, 2020]