Human factors issues involving the certification of today's transport flight decks are not limited to new aircraft design. To the contrary, most of today's certification activity involves upgrading the flight deck technology of “classic aircraft” or adding new after-market products to current designs. This can include such additions as Flight Management System (FMS) and Global Positioning System (GPS) interfacing to Autopilots and Flight Directors, Multi-Function Control and Display Units (MCDU), Satellite Communications (SatCom) and High Frequency (HF) Data Links, Heads-Up-Display (HUD) technologies, and even complete three-to-two pilot flight deck conversions. All of these changes impact the way in which crews are trained, qualified, and actually operate the aircraft.This paper reviews the background issues involved with minimum crew certification and describes current methods of workload evaluation in transport category aircraft. Included are a discussion of the relevant sections of current U.S. Federal Aviation Regulations (FARs) relating to the evaluation of workload and crew complement; the key elements of a workload evaluation (both its planning and the process); the use of simulation and/or aircraft in the evaluation; qualification and training of evaluation crews; and the design of flight test mission profiles for workload evaluation.