As used in this part:

Certificated air carrier means a U.S. carrier holding a certificate issued under 49 U.S.C. 41102 to conduct passenger service or holding an exemption to conduct passenger operations under 49 U.S.C. 40109.

Commuter air carrier means a U.S. carrier that has been found fit under 49 U.S.C. 41738 and is authorized to carry passengers on at least five round trips per week on at least one route between two or more points according to a published flight schedule using small aircraft as defined in 14 CFR 298.2.

Covered carrier means a certificated carrier, a commuter carrier, an air taxi, or a U.S. indirect carrier operating to, from, or within the United States, conducting scheduled passenger service or public charter service.

Indirect carrier means a person not directly involved in the operation of an aircraft who sells air transportation services to the general public other than as an authorized agent of a carrier.

This part applies to U.S. certificated air carriers, U.S. commuter air carriers, air taxis, and U.S. indirect carriers that operate passenger service to, from, or within the United States.

Each covered carrier shall permit a passenger to carry a violin, guitar, or other small musical instrument in the aircraft cabin, without charging the passenger a fee in addition to any standard fee that carrier may require for comparable carry-on baggage, if:

(a) The instrument can be stowed safely in a suitable baggage compartment in the aircraft cabin or under a passenger seat, in accordance with the requirements for carriage of carry-on baggage or cargo established by the FAA; and

(b) There is space for such stowage at the time the passenger boards the aircraft.

Each covered carrier shall permit a passenger to carry a musical instrument that is too large to meet the requirements of § 251.3 in the aircraft cabin, without charging the passenger a fee in addition to the cost of an additional ticket described in paragraph (e) of this section, if:

(a) The instrument is contained in a case or covered so as to avoid injury to other passengers;

(b) The weight of the instrument, including the case or covering, does not exceed 165 pounds or the applicable weight restrictions for the aircraft;

(c) The instrument can be stowed in accordance with the requirements for carriage of carry-on baggage or cargo established by the FAA;

(d) Neither the instrument nor the case contains any object not otherwise permitted to be carried in an aircraft cabin because of a law or regulation of the United States; and

(e) The passenger wishing to carry the instrument in the aircraft cabin has purchased an additional seat to accommodate the instrument.

Each covered carrier shall transport as baggage a musical instrument that is the property of a passenger traveling in air transportation that may not be carried in the aircraft cabin if

(a) The sum of the length, width, and height measured in inches of the outside linear dimensions of the instrument (including the case) does not exceed 150 inches or the applicable size restrictions for the aircraft;

(b) The weight of the instrument does not exceed 165 pounds or the applicable weight restrictions for the aircraft; and

(c) The instrument can be stowed in accordance with the requirements for carriage of carry-on baggage or cargo established by the FAA.