(2) A person who holds an airline transport pilot certificate and has met the aeronautical experience requirements of § 61.159 and the age requirements of § 61.153(a)(1) of this part may instruct— (i) Other pilots in air transportation service in aircraft of the category, class, and type, as applicable, for which the airline transport pilot is rated and endorse the logbook or other training record of the person to whom training has been given;
(ii) In flight simulators, and flight training devices representing the aircraft referenced in paragraph (a)(2)(i) of this section, when instructing under the provisions of this section and endorse the logbook or other training record of the person to whom training has been given;
(iii) Only as provided in this section, except that an airline transport pilot who also holds a flight instructor certificate can exercise the instructor privileges under subpart H of this part for which he or she is rated; and
(iv) In an aircraft, only if the aircraft has functioning dual controls, when instructing under the provisions of this section.