To answer the long-standing question of how to construct information systems to support heuristic decision making, we propose a new model of decision support for tacit knowledge. The aim of proposing a new model of decision support for tacit knowledge is to advance a general model of how experts describe the tacit aspects of their decision making. Such a model has implications for the construction of explanations by artificial intelligence. In a pilot case study of shift work planning, we explore the use of heuristics by consultants to interpret the conditions, outputs, and quality of shift work and to generate recommendations for changes to the organisation of shift work in organisations. The proposed, full case study to follow this pilot study will evaluate a conceptual model of decision support to inform how heuristics can explain decisions made by human, and by extension, artificial intelligence agents.