A new technique, Point Merge, for merging aircraft without vectoring in terminal areas (TMA), is modelled, and used in fast-time simulations. Four arrival traffic streams are merged for landing on a single runway. A method for designing fast-time models of vectoring and Point Merge is proposed and validated using real-time simulation trajectories. Relative performances of fast-time simulations of the corresponding models are compared. Interactions with departure traffic are also assessed. Results show the Point Merge model reduces: mean controller task load (20±1%), the number of instructions to pilots (~30%), and fuel consumption (170±14 kg), compared with vectoring.

This air traffic management research study analysed the interaction between a potential future airborne spacing application and an existing Airborne Collision Avoidance System (ACAS). The time-based airborne spacing application 'merge behind' was simulated in fasttime for a range of merge angles (45°, 90°, 135° and 180°), target spacing times (60 and 90 s) and altitudes (6,000 and 11,000 feet) under turbulent wind and extreme entry conditions. Trajectory pairs were analysed for potential collision alerting conditions using an ACAS simulator based on Traffic Alert and Collision Avoidance System (TCAS) II version 7 logic. Results show how, with realistic turn anticipation, the TCAS estimated time to go to Closest Point of Approach (CPA) decreased as merge angle was increased and as target spacing was reduced, but still remained above the Traffic Advisory (TA) and Resolution Advisory (RA) thresholds for the duration of all trials.

This air traffic management research study analysed the range of admissible entry conditions for using airborne spacing to sequence aircraft on multiple trajectories merging at a fixed waypoint. A guidance law was developed capable of merging multiple aircraft in descent under turbulent wind conditions. Effects of initial distances and speeds on the ability of an aircraft to descend from 29,000 to 3,000 feet and establish a stable spacing (8 NM) behind another by a given merge point were measured using fast-time simulations. Results for two aircraft at the same initial speed (272 knots calibrated airspeed) show how the possible initial spacing error envelope grew from [-0,+0] to [-22,+25] NM when the initial distance of the lead aircraft to the merge point was increased from 0 to 100 NM. The impact on initial spacing error of varying the difference in initial speed from-60 to +50 knots between the two aircraft was slight (magnitude less than 5 NM). Results for three aircraft of similar initial speeds are presented as contour maps to show how the initial spacing error envelopes of the second and third aircraft grew with initial distance of the lead aircraft to the merge point.

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The objective of this air traffic management study was to analyse the trade-off between time spacing accuracy and corresponding control effort in a potential future application of airborne separation assistance systems (ASAS). The ASAS application airborne spacing sequencing and merging was simulated in fast-time. Lead aircraft speed profiles were generated using complete descent profiles from real-time experiments. For validation purposes, three metrics were derived from real-time experiments: time spacing error (accuracy), frequency of speed adjustments (control activity), and cumulative airspeed variations (control cost). Four experimental parameters were varied: automatic and manual speed control, spacing dead-zone, guidance law dynamics time constant and initial time spacing error. A trade-off between the metrics was found for a sequence of two aircraft by comparing their variation with the experimental parameters. Corresponding 'minimum' performance requirements for the metrics are proposed: (i) time spacing error-mean less than 1.5s with 0.5 to 85% of the values between-4 and +4s (automatic mode), and mean less than 2.5s with 0.5 to 85% of the values between-6 and +6s (manual mode), (ii) frequency of speed adjustments-mean less than 1 action per minute (manual mode) and (iii) cumulative airspeed variations-mean less than 10 knots (automatic and manual modes). These requirements form a basis for investigating sequences longer than two aircraft where chain propagation effects may lead to additional constraints. Nomenclature