---
kind: "section"
citation: "14 C.F.R. § 121.431"
title: "14"
number: "121.431"
heading: "Applicability."
url: "https://uscodex.org/cfr/14/121.431"
---

# §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](/cfr/14/part142.md) of this chapter who meet the requirements of [§§ 121.411 through 121.414](/cfr/14/121.411..121.414.md) 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](/cfr/14/121.400.md) 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.


## Notes

### Amendments

[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]

### Authority

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).

### Amendments

[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]