Towards Performance Requirements for Airborne Spacing- A Sensitivity Analysis of Spacing Accuracy

Abstract

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

Airborne Spacing: Managed vs. Selected Speed Mode on the Flight Deck

“…An analysis of the contribution of each factor would be necessary. Model-based simulations have been performed 15 that allowed an initial quantification of the contribution of the air system (the other factor was negligible as the initial conditions were almost ideal). In conditions similar to the present experiment, the air system induced a cost of about 15kt on average with extreme values of +5kt and +40kt.…”

“…A better use of the tolerance and possibly a larger tolerance (although necessary for final approach, the tolerance margins of ±5s are probably unnecessary for initial approach) should help reducing the cost. An initial trade-off analysis has been performed through model-based simulations 15 . Figure 8.…”

Comparing Interval Management Control Laws for Steady-State Errors and String Stability

“…4 A number of speed control algorithms have been developed and tested to support various aspects of the research, including performance analyses using fast-time simulation, human-in-the-loop experiments, and flight tests. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The Federal Aviation Administration (FAA) is leading the development of avionics standards and the requisite ATC automation systems to enable IM operations in the U.S. National Airspace System. As a part of the avionics standards effort, a sample IM algorithm has been developed and tested and is described in the recentlypublished Flight-deck Interval Management (FIM) Minimum Operational Performance Standards (MOPS), DO-361.…”