Compression on final approach and Time Based Separation for optimized runway delivery

Presently Distance Based Separation (DBS) rules are applied during final approach. As these rules result in a loss in landing rate performance during (strong) headwind conditions, a new concept should be introduced to help maintain or improve the landing rate performance. For this purpose, the Time Based Separation (TBS) concept is in development; it involves changing separation rules on final approach by investigating the possibilities of preventing loss of runway capacity under strong wind conditions, while maintaining the required level of safety (Lepadatu, 2007). For going over DBS and modeling a TBS concept, a better characterization of the compression effect is required, which is the main goal of this report. Actual distance based separations are to be replaced by time intervals, and/or speed compensation. The problem is that the aircraft pair (leader-follower) flying different point on final approach differs in its speeds, causing the separation between the two paired aircraft to increase or decrease. Decreasing separation below the minima increases the risk of wake turbulence encounters. In addition, the headwind conditions should be taken into account since these will reduce the groundspeed and as such the time to fly when no speed compensation is applied. This study will predominately focus on these headwind conditions. The characterization issues extracted in this study are needed to feed or support the TBS FFH tool for building an airspeed profile for the leader and follower aircraft on final approach. The tool is able to include the following characterization effects: Approach Speed (Vapp), Deceleration and Stabilization Fix (DF & SF) and Glide Slope Speed. These performance parameters depend on the, aircraft type (wingspan/speed), wind profile, manufacturer (Airbus or Boeing), airline, part of the day and STAR. However, other challenging compression issues such as Time to Fly, current time separation, pilot/ATC practices and the Flight Management System (FMS) have also been analyzed in extensive detail and will act as recommendation for the future TBS studies. The data supporting the above conclusions is obtained from Charles De Gaulle (CDG) airport. To improve verification the results are compared with data from Vienna airport and show significant similarities, noting that DF and SF standard deviations are higher compared to the TAS and time to fly due to local ILS and IAP procedures. A comparison of CDG approach speed profiles with data used in RECAT-EU and Boeing data also shows significant similarities. In two case studies the new TBS FFH tool and the TBS OSED 1 tool are tested against real radar tracks. By comparing the performances of these two models, the best performances are extracted by looking at the least time separation error. In both studies the TBS FFH tool performed better. Finally, approach speeds, DF & SF and glide slope speeds resulting from this study have been used as input parameters in the SESAR Project 06.08.01 Validation Exercise for the TBS OSED Phase 2 model. Primarily results from this exercise indicate an improvement in runway throughput recovery applying the new TBS methodology when comparing low wind with high wind conditions.ATOATOAerospace Engineerin