(a) Required pilot certificate for operating a civil aircraft of the United States. No person may serve as a required pilot flight crewmember of a civil aircraft of the United States, unless that person:

(i) A pilot certificate issued under this part and in accordance with § 61.19;

(ii) A special purpose pilot authorization issued under § 61.77;

(iii) A temporary certificate issued under § 61.17;

(iv) A document conveying temporary authority to exercise certificate privileges issued by the Airmen Certification Branch under § 61.29(e); or

(v) When operating an aircraft within a foreign country, a pilot license issued by that country may be used.

(i) Driver's license issued by a State, the District of Columbia, or territory or possession of the United States;

(ii) Government identification card issued by the Federal government, a State, the District of Columbia, or a territory or possession of the United States;

(iii) U.S. Armed Forces' identification card;

(iv) Official passport;

(v) Credential that authorizes unescorted access to a security identification display area at an airport regulated under 49 CFR part 1542; or

(vi) Other form of identification that the Administrator finds acceptable.

(1) A person may serve as a required pilot flight crewmember of an aircraft only if that person holds the appropriate medical certificate issued under part 67 of this chapter, or other documentation acceptable to the FAA, that is in that person's physical possession or readily accessible in the aircraft. Paragraph (c)(2) of this section provides certain exceptions to the requirement to hold a medical certificate.