Impact of vertical situation information on vertical mode awareness in advanced autoflight systems

An examination of autoflight systems in modern aircraft was made, with emphasis on the complex mode structure which is suspect in several recent accidents. Aviation Safety Reporting System reports and Flight Mode Annunciator conventions were examined. Principal results identified the lack of a consistent global model of the Autoflight System architecture and identified the vertical channel as requiring enhanced feedback. Functional requirements for an electronic vertical situation display (EVSD) were created based on established conventions and identified mode awareness problems. A preliminary version of this display was prototyped and an evaluation methodology was proposed. A set of experimental scenarios based on various types of mode awareness problems was established and discussed.