Applicability

This regulation introduces Subpart O, which covers crewmember qualification requirements for Part 121 air carriers (scheduled airlines and commercial operators). It establishes that these qualification rules apply to all certificate holders unless the regulation specifically states otherwise.

The regulation also permits FAA-approved training centers operating under Part 142 to provide training, testing, and checking services to Part 121 operators through contracts, as long as the training center personnel meet specific requirements outlined in §§121.411-121.414.

Additionally, it defines three important terms used throughout the subpart:

• Consolidation: The practice period where pilots build proficiency in newly learned skills
• Line operating flight time: Actual flight time conducting Part 121 operations
• Operating cycle: One complete flight from takeoff through landing

These definitions establish the framework for understanding how pilot qualification and training requirements work in airline operations.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*