Trajectory Specification for Terminal Air Traffic: Arrival Spacing

Abstract

"Trajectory specification" is the explicit bounding and control of aircraft trajectories such that the position at each point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft navigation capabilities and the traffic situation. A standard language will be developed to represent these specifications and to communicate them by datalink. Assuming conformance, trajectory specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) system or datalink failure, hence it can help to achieve the high level of safety and reliability needed for automation. As a more proactive form of ATC, it can also be used to maximize airspace capacity and reduce the reliance on tactical backup systems during normal operation. It applies to both enroute airspace and the terminal area around airports, but this paper focuses on arrival spacing in the terminal area and presents maneuvers and algorithms for achieving a specified delay of runway arrival time.

Trajectory Specification for Terminal Airspace: Conflict Detection and Resolution

“…The main objective was to test the computational feasibility and preliminary operational feasibility of the Trajectory Specification concept applied to the detection and resolution of conflicts in terminal airspace. Arrival spacing based on speed changes and path stretch maneuvers was evaluated in a previous paper [11].…”

“…The minimum separation standard in terminal airspace is 3 n miles horizontally or 1000 ft vertically. Arrival spacing, which was addressed in a previous paper [11], is a one-dimensional delay problem, but general separation is three-dimensional and is therefore more complex. The approach taken here is to first solve the arrival spacing problem because that also solves most of the general separation conflicts for arrivals in the same arrival stream to a common runway.…”

“…Trajectory Specification is a proposed far-term enhancement of the Advanced Airspace Concept project being developed by NASA for automating ATC in both en route airspace [4][5][6] and the terminal airspace around major airports [7,8]. The Trajectory Specification concept was first published in 2005 [9] and has been updated in more recent publications [10][11][12] (and issued a U.S. patent). A similar proposal by others [13] with a more airborne focus followed several years after the first publication on the concept.…”

“…A previous paper presented results for Trajectory Specification applied to arrival spacing [11]. This paper presents fast-time simulation results for the full deconfliction process, including spacing and general conflict detection and resolution, for a full day of traffic in the terminal airspace around a major airport.…”

Trajectory Specification Language for Air Traffic Control

“…Trajectory Specification is a proposed far-term enhancement of the Advanced Airspace Concept (AAC) being developed by NASA for automating ATC in both enroute airspace [4][5][6] and the terminal airspace around major airports [7,8]. The Trajectory Specification concept was first published in 2005 [9] and has been updated in more recent publications [10][11][12] (and issued a US patent). A similar proposal by others [13] followed several years after the first publication on the concept.…”