This paper presents a new concept of optimized surface operations at busy airports to improve the efficiency of taxi operations, as well as reduce environmental impacts. The suggested system architecture consists of the integration of two decoupled optimization algorithms. The Spot Release Planner provides sequence and timing advisories to tower controllers for releasing departure aircraft into the movement area to reduce taxi delay while achieving maximum throughput. The Runway Scheduler provides take-off sequence and arrival runway crossing sequence to the controllers to maximize the runway usage. The description of a prototype implementation of this integrated decision support tool for the airport control tower controllers is also provided. The prototype decision support tool was evaluated through a human-in-the-loop experiment, where both the Spot Release Planner and Runway Scheduler provided advisories to the Ground and Local Controllers. Initial results indicate the average number of stops made by each departure aircraft in the departure runway queue was reduced by more than half when the controllers were using the advisories, which resulted in reduced taxi times in the departure queue.

Randomly sampled l i n e a r systems with linea? or non-linear feedback loops a r e studied by a stochastic Liapunov function method.The input, i n t h i s paper, i s assumed zero (driven systems w i l l be t r e a t e d i n a Companion paper), Improved c r i t e r i a f o r s t a b i l i t y (with probability one, on sth moment a r e given, when t h e sequence of holding times a r e independent. method i s r e l a t i v e l y straightforward to apply (especially i n comparison with the d i r e c t methods), and allows the study with nonl i n e a r feedback, or non-stationary holding times. A randomly sampled Lurg problem i s studied, some i n t e r e s t i n g phenomena (such as j i t t e r s t a b i l i z e d systems) a r e presented. s > 1, or i n mean square)The Numerical r e s u l t s , describing 1. Introduction The paper i s concerned with systems of t h e type of Fig. 1, where c i s a row vector, 2 = Ax i s assumed t o be asymptotically stable, and f(*) may be e i t h e r a l i n e a r or non-linear element. The case of s c a l a r valued f and u i s of main i n t e r e s t , although the method i s obviously usable when f and u a r e vector valued. The sampler samples a t a sequence of random times t h e holding i n t e r v a l s

Surface operations at airports in the US are based on tactical operations, where departure aircraft primarily queue up and wait at the departure runways. NASA's Spot And Runway Departure Advisor (SARDA) tool was developed to address these inefficiencies through air traffic control tower advisories. The SARDA system is being updated to include collaborative gate-hold, either tactically or strategically. This paper presents the results of the human-in-the-loop evaluation of the tactical gate-hold version of SARDA in a 360 simulated tower setting. The simulations were conducted for the east side of the Dallas/Fort Worth airport. The new system provides gate-hold, ground controller and local controller advisories based on a single scheduler. Simulations were conducted with SARDA on and off, the off case reflecting current day operations with no gate-hold. Scenarios based on medium (1.2x current levels) and heavy (1.5x current levels) traffic were explored. Data collected from the simulation were analyzed for runway usage, runway queue size, delay for departures and arrivals, and fuel consumption. Further, traffic management initiatives were introduced for a subset of the aircraft. Results indicated that runway usage did not change with the use of SARDA, i.e., there was no loss in runway throughput

SUMMARYA prototype expert system has been developed for the time scheduling of aircraft into the terminal area. The three functions of the air-traffic-control schedule advisor are as follows: First, for each new arrival, it develops an admissible flight plan for that aircraft. Second, as the aircraft progresses through the terminal area, it monitors deviations from the aircraft's flight plan and provides advisories to return the aircraft to its assigned schedule. Third, if major disruptions such as missed approaches occur, it develops a revised plan. The advisor is operational on a Symbolics 3600, and is programmed in MRS (a logic programming language), Lisp, and Fortran.