Analysis of in-trail following dynamics of CDTI-equipped aircraft

Abstract

The Cockpit Display of Traffic Information (CDTI) system is being developed to enable pilots to observe the surrounding air traffic pattern. The CDTI application of directly allowing the pilots to maintain in-trail spacing (following) along terminal area approach paths is examined. First, the following dynamics governed by the choices of separation criteria are analyzed. Then the results of several cockpit simulator experiments of in-trail following tasks are used to assess the performance of the pilot/aircraft/CDTI system in acquiring and maintaining adequate spacing dynamics. Based on collected simulator data, a mathematical model of the longitudinal system dynamics is formulated. This model can be used to examine various dynamics phenomena and the stability of a string of aircraft along the approach path. Experimental results are also used to examine longitudinal spacing control effects on vertical and lateral path control. IntroductionB OTH the use of more automation and more involvement of the pilot in the air traffic control (ATC) process are well understood to be future needs for providing greater terminal area capacity. A joint NASA-FAA research project is being conducted to explore uses of the cockpit display of traffic information (CDTI) to meet these needs. ! One application of particular interest is the use of the CDTI display by the pilot for nonvectored clearances relative to other traffic. Under this category are functions such as control into a traffic merge point and spacing along a route. In order to derive the control requirements for such functions, it is first necessary to understand the dynamics of merging and trailing aircraft.Several questions arise associated with these CDTI-based terminal area traffic tactical control concepts. These include:1) What are the basic dynamic phenomena associated with independently controlled aircraft in a string?2) What conditions would produce instability in the string? 3) What information does each pilot need (from the CDTI and elsewhere) to merge his aircraft adequately into the string and then to maintain appropriate spacing (along with normal lateral and vertical guidance functions)? 4) What are the effects of measurement and display errors, wind shears, aircraft mixes, spacing constraints, and merge trajectories on the dynamics and control performance of the system? 5) What advantages does this concept have compared to ground-based control?This study begins to address these questions from a systems point of view. In particular, only the first three questions are addressed in this paper. BackgroundThe flight system (i.e., the pilot/aircraft/CDTI combination interacting with other aircraft and ATC) is assumed to be entering the terminal area and proceeding along an established approach to landing. A sketch of such a scenario is depicted in Fig. 1.

Influence of speed and altitude profile on the dynamics of in-trail following aircraft

“…The constant time delay has probably the best potential for position based ToD since it requires almost no speed variation to maintain the desired separation very accurately. This consideration is consistent with previous studies e.g [13][16]…”

“…Going back to the 80s, one of the first studies in the domain of in-trail following aircraft is presented in [13]. The study covered both analytical and experimental aspects.…”

“…A series of studies dating back to the beginning of the 80s aimed at capturing the essence of Station Keeping [6][7] [13] [14][15] [16]. Three separation criteria were defined along with their corresponding cockpit display cues, and their performances were evaluated using both cockpit simulators and mathematical models.…”

Assessing the Impact of a New Air Traffic Control Instruction on Flight Crew Activity

“…12 A mathematical model (including pilots' behaviour) of chain of aircraft under spacing in final approach could not show any unstable oscillations as well. 11 More recent pilot-in-the-loop simulations broadened their scope including aircraft on converging trajectories, with the objective of assessing the appropriate level of assistance onboard. [9][10] The combination of descriptive information (display cues) and normative information (procedures) appeared to allow better anticipation and, hence, improve safety.…”

A Pilot Decision Support Tool for Merging behind a Lead Aircraft

“…Two new main kinds of spacing instruction 'merge behind' and 'remain behind' are being evaluated in air traffic controller [4] and pilot in the loop [5] Past studies have investigated both distance and time based airborne spacing of sequences of aircraft using fast time [1], [6], [10] and real-time experiments [8], [14], [15] (and references therein). Time based spacing has been found to have several potential advantages over distance based spacing ( [1], [ 13] and references therein).…”