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Supporting pilot situation awareness is considered essential in safeguarding safety. There is much disagreement, however, regarding a formal definition of situation awareness. On the one hand, the most commonly cited definition, from a cognitive perspective, describes it in terms of human information processing stages involving the three levels of perception, comprehension and projection. On the other hand, an ecological approach exists that focuses on defining the ‘situation’ instead of the ‘awareness’, using Rasmussen’s abstraction hierarchy. This paper investigates the usefulness of the ecological approach in defining pilot terrain awareness. An abstraction hierarchy is defined that captures the characteristics of situations involving terrain awareness. It is used to explore the informational content in existing terrain awareness enhancing avionics. Suggestions will be made on how to enhance them to better support pilot terrain awareness from an ecological perspective.