The scope of this document is primarily concerned with human factors issues relating to the use of head-up displays in civil transport airplanes. It addresses issues associated with the interface provided by the head-up display with aircraft systems and the interface provided by the head-up display with the real-world, including the external visual scene. More specifically it examines the symbology: form, dynamic behavior, and relationship within families of symbols. It also examines the relationship of these symbols with the visual scene. The purpose of this document is to provide a compilation of human factor issues regarding the impact of head-up displays on flight operations in the terminal area and flight navigation in the airspace system.