49 CFR § 1544.223 - Transportation of Federal Air Marshals.
(a) A Federal Air Marshal on duty status may have a weapon accessible while aboard an aircraft for which screening is required.
(c) Each Federal Air Marshal must be carried on a first priority basis and without charge while on duty, including positioning and repositioning flights. When a Federal Air Marshal is assigned to a scheduled flight that is canceled for any reason, the aircraft operator must carry that Federal Air Marshal without charge on another flight as designated by TSA.
(d) Each aircraft operator must assign the specific seat requested by a Federal Air Marshal who is on duty status. If another LEO is assigned to that seat or requests that seat, the aircraft operator must inform the Federal Air Marshal. The Federal Air Marshal will coordinate seat assignments with the other LEO.
(e) The Federal Air Marshal identifies himself or herself to the aircraft operator by presenting credentials that include a clear, full-face picture, the signature of the Federal Air Marshal, and the signature of the FAA Administrator. A badge, shield, or similar device may not be used or accepted as the sole means of identification.
(f) The requirements of § 1544.219(a) do not apply for a Federal Air Marshal on duty status.
(g) Each aircraft operator must restrict any information concerning the presence, seating, names, and purpose of Federal Air Marshals at any station or on any flight to those persons with an operational need to know.
(h) Law enforcement officers authorized to carry a weapon during a flight will be contacted directly by a Federal Air Marshal who is on that same flight.