Text in force at 25-153: from 25-3, effective 28 May 1965.
The minimum flight crew must be established so that it is sufficient for safe operation, considering--
(a) The workload on individual crewmembers;
(b) The accessibility and ease of operation of necessary controls by the appropriate crewmember; and
(c) The kind of operation authorized under Sec. 25.1525. [The criteria used in making the determinations required by this section are set forth in Appendix D.]
30 FR 6067 · Source