Aircraft requirements: General

This regulation sets the basic aircraft requirements for Part 121 air carriers. Generally, certificate holders must operate aircraft that are U.S.-registered civil aircraft with current airworthiness certificates, and the aircraft must be in airworthy condition meeting all applicable requirements.

Certificate holders may use approved weight and balance systems based on average or estimated weights rather than actual measurements for each flight.

There's an important exception: carriers can operate foreign-registered aircraft without crew (dry lease or charter) for passenger and mail operations if the aircraft:

• Carries a valid airworthiness certificate from its country of registration (which must be party to the Chicago Convention)
• Conforms to a U.S. type certificate and meets all U.S. requirements as if it were U.S.-registered
• Is flown by U.S.-certificated airmen employed by the carrier
• Has its lease/charter agreement filed with the FAA Aircraft Registry in Oklahoma City

This exception allows carriers operational flexibility with foreign-registered aircraft while maintaining safety standards.

*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.*