In this paper we present a system that generates questions from an ontology to determine a crisis situation by ordinary people using their mobile phone: the Situation Awareness Question Generator. To generate questions from an ontology we propose a formalization based on Situation Theory and several strategies to determine a situation as quickly as possible. A suitable ontology should comply with human categorization to enhance trustworthiness. We created three ontologies, i.e. a pragmatic-based ontology, an expert-based ontology and a basiclevel ontology. Several experiments, published elsewhere, showed that the basic-level ontology is most suitable.