14 CFR § 121.431 - Applicability.

---
identifier: "/us/cfr/t14/s121.431"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 121.431 - Applicability."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "121.431"
section_name: "Applicability."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "G"
subchapter_name: "AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION AND OPERATIONS"
part_number: "121"
part_name: "OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 106(f), 40103, 40113, 40119, 41706, 42301 preceding note added by Pub. L. 112-95, sec. 412, 126 Stat. 89, 44101, 44701-44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44729, 44732; 46105; Pub. L. 111-216, 124 Stat. 2348 (49 U.S.C. 44701 note); Pub. L. 112-95, 126 Stat. 62 (49 U.S.C. 44732 note); Pub. L. 115-254, 132 Stat. 3186 (49 U.S.C. 44701 note)."
cfr_part: "121"
---


# 121.431 Applicability.

(a) This subpart:

(1) Prescribes crewmember qualifications for all certificate holders except where otherwise specified; and

(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]