Innovative technologies pose special difficulties for design engineers, because decisions have to be made under limited knowledge. Additionally, the designer has to go beyond the known operational principle and/or normal configuration. The design problem in such radial design thus has fewer limits on the solution space and so it becomes very ill-structured. It could be argued that design engineers just have to follow an existing politically sanctioned and socially accepted framework to make design choices. However, as a result of the ill-structured nature of radical design problems in innovative technologies a regulative framework is missing or inadequate. In making radical engineering designs, the engineers thus have to rely on other tools to make design choices. At present, design engineers use various tools, like rational decision making, multi-criteria analysis, and satisficing. However, these tools have been criticised, for example on the inability to cope with limited knowledge, Arrow’s impossibility theorem, or value incommensurability. Although, these type of tools have fundamental difficulties they are still taught in engineering curricula and routinely used in practise. The question arises whether design engineers are aware of these shortcomings and, if so, how they cope with these difficulties. This question is explored in several case studies by following design teams of graduate and post-graduate students making conceptual process and/or product designs. It will be shown that the design engineers are hardly aware of the criticisms on the tools they regularly apply and they utilize the tools differently than intended or employ them only partly. However, it will also be shown that this alternative application of the tools doesn’t always lead to desirable decisions. Therefore, it will be argued that to make desired design decisions new tools are needed for engineering design in innovative technologies. Requirements for the new tool, such as it should work under limited knowledge and in accordance with engineering design practice, will be presented. The presented results are the first part of a research project from the Kluyver Centre and the 3TU Centre. In the second part of the research the new tool will be formulated and implemented in design engineering practice. The initial setup of the design tool for the second phase will be brought forward for discussion.