A study of commercial flight crew self-separation

The concept of "free flight" is intended to emphasize more flexibility for operators in the National Airspace System by providing more opportunities for aircraft self-separation. The purpose of this simulation was to begin examining some of the communication and procedural issues associated with self-separation in the enroute environment. A simulation demonstration was conducted in the Boeing 747-400 simulator at NASA Ames Research Center. Commercial U.S. Pilots current on the B747-400 aircraft were the participants. Ten flight crews flew in the Denver enroute airspace. A new alerting logic designed to allow for airborne self-separation was created for this demonstration. New flight deck display features were designed and incorporated into the existing navigational display in the simulator to allow for increased traffic and maneuvering information to the flight crew. Each of the flight crews flew eight different scenarios representing different conflict types. The effects of traffic density (high and low) and the introduction of an "almost intruder" (AI) aircraft were assessed. Loss of separation was assessed as a safety metric. Timing variables and maneuver strategies were examined to determine potential differences in efficiency of navigation in free flight based on scenario and conflict type. Data analyses on crew procedures revealed few findings associated with traffic density; however, the AI scenario suggested some relationship between display changes for alert levels and self-separation procedures. The impact of these findings on free flight procedural definitions and the identification of future work are discussed.