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4.3.8.1 Problem
ATSP generally does not accommodate user preferences for arrival metering/spacing processes used to manage arrival delays, while the aircraft is operating in en route, extended terminal (includes terminal and parts of en route) and terminal airspace.
When arrival demand exceeds airport capacity, arrival scheduling is used to maximize throughput while efficiently distributing delay from terminal to en-route airspace. Scheduling is generally based on an estimated time-of-arrival (ETA) based first-come-first-served (FCFS) order with minimum spacing between sequential flights (to avoid conflicts and wake vortices). Spacing criteria, typically defined as a function of runway configuration and meteorological conditions, are applied at runway, approach, and meter-fix (TRACON entry) merge points. Key scheduling factors include the assignment of runway and meter-fix, choice of sequence and the relative sequence of flights in an arrival stream.
In the current system, users are generally unable to influence arrival metering/spacing processes used for managing arrival delays. The extent of arrival metering/spacing may be excessive, and the distribution of delay inequitable, because of inaccuracies in the prediction of arrival traffic load. Accurate metering requires accurate prediction of traffic demand and airspace/runway capacity. In particular, errors in predicted arrival routing and ETAs may cause scheduling errors resulting in excess delays for particular flights. A critical situation, often leading to large ETA errors, involves terminal area traffic that depart their origin airport within the extended terminal area scheduling freeze horizon. Slots for these flights are difficult to plan for and are often based on information such as the flight planned departure time. For those cases, ETA uncertainty is magnified several times by the uncertainties associated with estimating the precise departure time since flights may be subject to significant delays on the ground (e.g., mechanical problems, waiting for the crew to arrive) or even cancellation, without the knowledge of the scheduling system.
Transition Airspace
ARTCC 2
ARTCC 1
TRACON
ARTCC 3
Fig. 4-6: Schematic of Arrival Metering Problem
4.3.8.2 Solution
Users influence arrival handling by submitting preferences for arrival time, meter-fix and runway to the ATSP well in advance of the arrival-planning freeze horizon.
Using arrival-planning DSTs, users (AOC and/or FD) determine arrival preferences (arrival time, runway and meter-fix) that conform to all known NAS constraints. Meter-fix and runway preferences allow the user to influence their arrival routing and taxi time. Arrival time preferences help all users to maintain their arrival schedule; they also enable “hubbing” users to influence the sequencing of flights in their arrival banks. In addition to the nominal preferences, the user could also specify a “delay weighting” for each runway and meter-fix. For example, a user may nominally prefer runway 28-left. However, if the delay for 28-L were to exceed some threshold compared to another runway, the preference would change to the other runway. The same would apply to a meter-fix entry point where a user may prefer to fly a longer path to enter the TRACON from another fix in order to avoid excessive delays along the more direct path.
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Concept Definition for Distributed Air/Ground Traffic Management (DAG-TM)(28)
