Autoflight mode management is the process involved in understanding the character and consequences of autoflight modes, planning and selecting engagement, disengagement and transitions between modes, and anticipating automatic mode transitions made by the autoflight system itself. The full detail of autoflight logic is probably too complex to be easily understood, even by the engineers who created it. The logic diagrams that describe the behavior of the system in all anticipated conditions are typically composed of diagrams that span dozens of pages. Much of this complexity arises from rarely encountered conditions. Still, the actual behavior of the autoflight system in operational circumstances can be baffling [9] Funk and his colleagues [3] conducted a major review of perceived human factors problems of flightdeck automation. This study showed that the complexity of automation and failures of pilot understanding of automation were thought by industry professionals to be major problems. Sarter and Woods [5,6] have documented failures of pilot understanding of autoflight modes via both observational and experimental methods. In the face of this complexity and the problems it seems to cause, pilots should and do apparently develop and use simplified models of what the autoflight system is doing. Ultimately, we are most interested in what pilots do with respect to autoflight functions. Presumably, what pilots do is related to how they think about autoflight, which is in turn related to what they know about autoflight. To date, there has been no systematic study of what pilots actually do know about autoflight. Such a study is one component of this project. That component will be descriptive rather than proscriptive in nature. It will use primarily ethnographic methods to determine how pilots conceive of autoflight mode management (especially vertical mode management).