The purpose of this document and its sequels is to provide a set of human factors guidelines for facilitating and fostering human trust in Air Traffic Management (ATM) systems. The guidelines are primarily concerned with the trust of computer-assistance tools and other forms of automation support, which are expected to be major components of future ATM systems. This deliverable, on the subject of trust guidelines, is the first one developed within the Solutions for Human-Automation Partnerships in European ATM (SHAPE)' Project. There are two subsequent deliverables on trust issues; one is dealing with the measurement of trust (see EATMP, 2003a), the other provides detailed info about trust principles (see EATMP, 2003b).