While human-system interaction occurs in all phases of system development and operation, this chapter on Human Factors in the DDT&E for Reliable Spacecraft Systems is restricted to the elements that involve "direct contact" with spacecraft systems. Such interactions will encompass all phases of human activity during the design, fabrication, testing, operation, and maintenance phases of the spacecraft lifespan. This section will therefore consider practices that would accommodate and promote effective, safe, reliable, and robust human interaction with spacecraft systems. By restricting this chapter to what the team terms "direct contact" with the spacecraft, "remote" factors not directly involved in the development and operation of the vehicle, such as management and organizational issues, have been purposely excluded. However, the design of vehicle elements that enable and promote ground control activities such as monitoring, feedback, correction and reversal (override) of on-board human and automation process are considered as per NPR8705.2A, Section 3.3. Adelstein, Bernard and Hobbs, Alan and OHara, John and Null, Cynthia Langley Research Center NASA/TM-2006-214535, L-19317, NESC-RP-06-108/05-173-E HUMAN FACTORS ENGINEERING; SYSTEMS ENGINEERING; ACTIVITY (BIOLOGY); GROUND BASED CONTROL; HUMAN REACTIONS; PROCEDURES; FABRICATION; FEEDBACK; MAINTENANCE