WO2011156027A1 - Runway clearance advisor - Google Patents

Abstract

A system and method is provided to support airport runway traffic controllers managing landing, takeoff and runway taxi operations at a single airport or integrated multiple airports. The system and method determine the traffic situation on the airport surface and in the airspace proximate to the airport to identify candidate aircraft or other vehicles for runway landing, takeoff and taxi entry at the current instant and assesses a comprehensive set of constraints to determine which aircraft or other vehicle should initiate a runway operation immediately. The constraints include inter- aircraft distance and time minimum spacing requirement, blockages due to aircraft and other vehicles on the runway and externally- derived traffic restrictions. The system and method generate runway takeoff clearance advisories for departure aircraft, initiate missed approach instruction advisories for arrival aircraft and runway clearance advisories to taxi across or along runways for aircraft and other vehicles.

Description

RUNWAY CLEARANCE ADVISOR

Cross Reference to Related Application

This application claims the benefit of U.S. Provisional Application 61/353,729 having a filing date of June 11, 2010, the entirety of which is incorporated herein by reference.

Field of the Invention

[0001] This invention relates to a system and method for increasing the efficiency of airport runway takeoff, landings and taxi operations by aircraft and other vehicles, and providing advisories that satisfy inter-aircraft spacing requirements and avert blockages due to runway occupancy by aircraft and other vehicles.

Background of the Invention

[0002] Runway controllers in airport air traffic control towers currently issue runway takeoff clearances (instructions) to departure aircraft and issue clearances to aircraft and other vehicles to taxi across or along runways. Airspace controllers issue runway approach instructions and landing assignments to arrival aircraft. Although the runway approach instructions and landing assignments normally are not determined by the runway controllers, these instructions and assignments are in conformance with procedures previously negotiated between the runway controllers and airspace traffic controllers. The runway controllers routinely accept these landing assignments, and issue landing clearances to the aircraft approaching the runways. The runway controllers then fit takeoffs and runway taxi movements around the aircraft landings in conformance with procedural requirements.

However, in cases where landing assignments are not in conformance with procedural requirements, the runway controllers issue missed approach instructions to abort these aircraft landings.

[0003] The runway controllers monitor the positions and movements of aircraft on the airport surface and in the airspace proximate to the airport surface by direct visual observation and viewing electronic surveillance system displays, where available, and mentally determine appropriate clearances and instructions based on their judgment and rules defining runway usage, aircraft minimum separation requirements and other restrictions. At any instant, runway controllers evaluate the current positions and movement states of aircraft and other vehicles, estimate predicted positions, judge the relative distance and time spacing among aircraft, and decide which aircraft should be cleared to initiate their runway operations or alter their runway operations.

[0004] While the decision processes of runway controllers are generally effective for runway operations, the decision processes are occasionally subject to

miscalculations. Miscalculations can result in inefficient sequences of runway usage by aircraft, introducing unnecessary delays. Inaccurate estimates of projected time or distance spacing between aircraft could lead to violations of separation requirements, thereby potentially compromising safety. Efforts to minimize such errors by applying spacing buffers could exacerbate delays. These potential impacts tend to become more consequential during congested periods of very busy traffic on the runways and taxiways of the airports.

[0005] Further, runway controllers focus almost exclusively on their airport and the operations in the airspace proximate to their airport, with limited information on nearby airport operations and airspace traffic. These runway controllers apply procedures and associated spacing rules established for their airport, which are integrated into standardized operations of the general local area. Controllers issue clearances conforming to terminal airspace departure and arrival procedures (routing paths) serving an airport. Takeoff clearances at many major airports are issued independently of other control jurisdictions based on the traffic situation and procedures at the airport. Other airports may require approval by other control authorities for individual takeoff requests, often incurring delays due to the coordination process. In either case, runway controllers must take into account aircraft spacing requirements at each departure fix in the airspace before issuing takeoff clearances. These spacing requirements are applied to successive aircraft departing the airport to a common departure fix without specific information regarding traffic from other airports proceeding to the same fix. This process leads to congestion due to competition among flights from different local airports for the common departure fix, resulting in delays and diversions.

[0006] In addition, runway controllers receive and apply constraints on departure flights from external control authorities. These include takeoff time restrictions (e.g., allowed takeoff time window or earliest takeoff time) for specific flights as well as spacing or flow rate constraints on departure flights destined to specific airports, airspace fixes, routes or regions. Here, runway controllers again make judgments on the best takeoff time for each flight to accommodate the externally- imposed restriction while satisfying local procedural requirements. Such judgments are subject to potential miscalculations leading to unnecessary delays.

[0007] Prior art methods that generally address management of runway operations are related to various automated systems for observing and analyzing airport surface traffic movement. These prior art methods use automated systems to track aircraft and other vehicles, monitor movement, detect potential conflicts or runway incursions, and display traffic state and prediction data to controllers and pilots. Examples of such prior art methods are described in the following patents:

U.S. Patent No. 5,548,515 discloses a precise 3-dimensional digital map of the airport with a GNSS positioning reference system, radio equipment on aircraft/vehicles to transmit GNSS position reports, a computerize system for receiving position reports and interpreting, assessing and displaying path information on a monitor, and computer processing for detection of zone incursions, collision conditions and on and off course situations and assignment of traffic controller responsibility, scheduling and lighting control.

U.S.. Patent No. 6,161,097 discloses a data management system for acquiring, integrating and managing real-time data generated at different rates from a variety of airline, airport operations, ramp control and air traffic control tower sources to establish and update descriptions of every aircraft surface operation. U.S. Patent No. 6,278,965 discloses a real-time surface traffic

management, knowledge-based, expert advisor system for acquiring, fusing, interpreting, mining and displaying real-time predictive and processed data for surface traffic management or training simulations, including future surface traffic event predictions.

U.S. Patent No. 6,694,249 discloses on-board aircraft situational awareness system for surface aircraft cockpit flight crew members that provides an integrated surface moving map advisory system that includes information describing airport layout, present aircraft location and speed; aircraft movement clearance received from the traffic controller and other airport traffic.

U.S. Patent No. 7,117,089 discloses a ground runway awareness and advisory system that provides position information and airport situational awareness alerts and advisories to pedestrians and vehicle operators during surface operations including aural, textual, graphic or pictographic alerts and advisory messages.

U.S. Patent Application Publication No. 2010/0100257 discloses the use of computer programming logic and mediums for providing visual airport surface and terminal data using data fusion, large-scale data storage, data exchange and graphical interface capabilities to display air traffic data for analysis.

U.S. Patent No. 6,789,011 discloses allocating and issuing

arrival/departure slot times at a selected point/fix that defines a planned schedule of aircraft arrival times at this fix such that slot times conform to acceptance rates at this fix, but does not specifically address interactions among multiple runways.

[0008] None of these prior art methods provide controller instructions needed for safe and efficient movement of aircraft and other vehicles on runways to satisfy aircraft spacing rales and resolve blockage constraints (where aircraft and other vehicles on runways obstruct each other).

[0009] Other prior art methods either schedule or optimize airport takeoff operations or airport landing operations, but generally not both operations. These methods are complex, computationally intensive and many are not able to provide rapid updates necessary to support management of runway operations under heavy and dynamic airport traffic conditions. Scheduling and optimization are not required by the present invention. Exemplary prior art methods along this line include:

Balakrishnan, H, Chandran, B., "Scheduling Aircraft Landings Under

Constrained Position Shifting," AIAA 2006-6320, Guidance, Navigation, and Control Conference and Exhibit, Keystone, CO (August 21-24, 2006) discloses investigating constrained position shifting and dynamic programming-based optimization approaches to schedule aircraft landings in order to maximize runway throughput (minimize completion time in the landing sequence) subject to operational constraints such as minimum inter-aircraft spacing requirements, aircraft overtaking precedence relationships and time window constraints on landing re-sequencing decisions.

Berge, M.E., Haraldsdottir, A., Scharl, J. "The Multiple Runway Planner (MRP): Modeling and Analysis For Arrival Planning," DASC 2006-2C4, Digital Avionics Systems Conference, Portland, OR (October 15, 2006) discloses a multiple runway planner tool for determining preferred aircraft arrival sequencing, scheduling and runway assignments based on optimizing airspace fix crossing and runway operations to meet a variety of optimization functions subject to aircraft spacing constraints.

Brinton, C.R., "An Implicit Enumeration Algorithm for Arrival Aircraft Scheduling," Eleventh Digital Avionics Systems Conference (DASC), Seattle, WA (October 1992) discloses introducing an implicit enumeration algorithm to optimize aircraft arrival sequences and schedules in a dynamic data feedback environment, enabling both runway and sequence assignment in the scheduling process.

Capozzi, B.J., Atkins, S.C., Choiz, S. "Towards Optimal Routing and Scheduling of Metroplex Operations," AIAA 2009-7037, Aviation Technology, Integration, and Operations (ATIO) Conference, Hilton Head, SC (September 21- 23, 2009) discloses a mixed integer linear programming formulation which simultaneously solves routing and scheduling alternatives for arrival and departure traffic for multi-airport traffic.

Couluris, G., Mittler, N., Stassart, A., Signor, D., and Hsiao, T., "A New Modeling Capability for Airport Surface Traffic Analysis," DASC 2008-3E4, Digital Avionics System Conference, St. Paul, MN (October 26-28, 2008) and

Couluris, G.J., Davis, P.C., Mittler, N.C, Saraf, A.P., Timar, S.D, "ACES Terminal Model Enhancement," DASC 2009-130, AIAA 28th Digital Avionics Systems Conference, Orlando, FL, (October 27, 2009) both disclose fast-time computer simulations that reschedule and re-sequence aircraft landings, takeoffs and taxi crossings at an airport to meet aircraft spacing and runway occupancy constraints by scheduling and assigning holds over future time, where hold assignments selectively stop aircraft and other vehicle movement prior to runway entry.

Davis, T.J., Erzberger, FL, Green, S.M., and Nedell, W., "Design and Evaluation of the Final Approach Spacing Tool," Journal of Guidance, Control and Dynamics, Vol. 14, No. 4, pp 848 - 854, (July-August 1991) discloses an

automated final approach spacing tool that generates four-dimensional aircraft trajectory predictions and sequences and schedules airport arrival traffic to meet local procedural requirements and runway and airspace aircraft spacing constraints with the capability to reduce controller workload and increase airport landing rates.

Deau, R., Gotteland, JB, Durand, N., "Airport Surface Management and

Runways Scheduling," ATM2009-081, Eighth USA/Europe Air Traffic

Management Research and Development Seminar discloses examination of runway sequence optimization solutions, using branch and bound techniques, to determine preferred methods for scheduling aircraft movement in consideration of interactions among airport runway arrivals and departures and surface traffic, runway aircraft spacing rules and taxiing constraints.

Gupta, G., Malik, W., Jung, Y.C., " Mixed Integer Linear Program for Airport Departure Scheduling, " AIAA 2009-6933, Aviation Technology,

Integration, and Operations (ATIO) Conference, Hilton Head, SC (September 21- 23, 2009) discloses a mixed integer linear program for deterministically scheduling departure aircraft at runways, allowing for different schemes for managing runway takeoff queuing including first-come first-served, unconstrained order and prioritization using time windows, all subject to aircraft separation criteria.

Rathinam, S., Wood, Z., Banavar Sridhar, B., Yoon Jung, Y., "A Generalized Dynamic Programming Approach for a Departure Scheduling

Problem," AIAA 2009-6250, AIAA Guidance, Navigation, and Control (GNC) Conference, Chicago, IL (August 10-13, 2009) discloses application of a

generalized dynamic programming approach to optimize departure schedule planning with respect to reducing total aircraft delays subject to timing and ordering constraints .

Wood, Z., Rathinam, S., "A Simulator for Modeling Aircraft Surface Operations at Airports," AIAA 2009-5912, Modeling and Simulation (MST) Conference, Chicago, IL (August 10-13, 2009) discloses the application of scheduling algorithms to integrate airport surface taxiway and runway operations, and demonstrates the application of a dynamic programming departure scheduler with first-come first-serve taxiway heuristics to manage delay.

[0010] What is needed is a method for increasing the efficiency of airport runway takeoff, landings and taxi operations by aircraft and other vehicles by rapidly and accurately determining the position and assigned path of each aircraft and vehicle on the airport surface and aircraft in the airspace proximate to the airport surface, simultaneously considering constraints on departure flights from external control authorities, and providing advisories that satisfy inter- aircraft spacing requirements and avert blockages due to runway occupancy by aircraft or other vehicles. Summary of the Invention

[0011] According to a first aspect of the present invention, there is provided a method for providing clearances for managing vehicle movement on a runway at an airport, the method comprising receiving airport infrastructure information comprising status of airport runways, taxiways, airspace fixes and route procedures, operating parameters and traffic restrictions, determining a current position for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport at a predetermined time interval, receiving an assigned path for each aircraft and other vehicle moving on an airport surface, receiving traffic control advisories and instructions issued by traffic controllers, and updating the runway system blockage status. The method including generating an initiate missed approach instruction advisory for a pending landing aircraft if runway blockage is present on the runway when the pending landing aircraft is crossing or has crossed a user-defined missed approach point at the current instant, communicating to a traffic controller the initiate missed approach advisory that includes instructions for the pending landing aircraft to abort landing on the runway, generating a preemptive runway taxi crossing clearance advisory for taxiing aircraft or other vehicles in a queue when a number of taxiing aircraft or other vehicles in the queue exceeds a user-defined limit, and communicating to the traffic controller the preemptive runway taxi crossing clearance advisory that includes^' instructions for one or more aircraft or other vehicles to proceed across a segment of a runway. The method including generating a runway takeoff clearance advisory for a pending departure aircraft that is either next in line to enter the runway for takeoff, or is currently positioned on the runway ready to takeoff when no part of the runway to be traversed is blocked at or forward of the current position of the pending takeoff aircraft, communicating to the traffic controller the runway takeoff clearance that includes instructions for the pending departure aircraft to proceed to takeoff on the runway; generating a runway taxi crossing clearance advisory for a pending taxiing aircraft or other vehicle that is next in line to enter the runway and taxi across or along the runway when no part of the runway to be traversed is blocked at or forward of the current position of the pending taxi aircraft or other vehicle; and communicating to the traffic controller the runway taxi crossing clearance advisory that includes instructions to proceed across or along a segment of a runway. [0012] In some embodiments of the present invention, generating the runway takeoff clearance advisory for the pending takeoff aircraft comprises determining the eligibility of each pending aircraft for takeoff from each runway and selecting one eligible aircraft for each runway for runway takeoff clearance advisory generation. In other embodiments, determining the eligibility of a pending aircraft for takeoff from each runway comprises determining whether aircraft minimum spacing requirements, runway blockage constraints and traffic restrictions are satisfied for the pending aircraft for takeoff.

[0013] In some embodiments, determining aircraft minimum spacing

requirements are satisfied for the runway takeoff clearance advisory comprises comparing a current position of each pending takeoff aircraft on each runway with a current position of predecessor aircraft and a current position of successor aircraft on the same runway and different runways and determining that time spacing and distance spacing between the current position of the pending takeoff aircraft and the current position of predecessor aircraft and successor aircraft exceeds aircraft minimum spacing requirements. In some embodiments, comparing aircraft time spacing and distance spacing between aircraft on different runways includes runways on a single airport and runways on different airports.

[0014] In some embodiments, determining runway blockage constraints comprises determining that no part of the runway to be traversed at or forward of the current position of the pending takeoff aircraft is blocked. In other

embodiments, determining whether traffic restrictions for a runway takeoff clearance are satisfied comprises determining that the pending aircraft taking off at the current instant complies with at least one of a takeoff time window and an earliest takeoff time.

[0015] In some embodiments, generating the initiate missed approach instruction advisory comprises determining that the landing runway is not blocked at or forward of the threshold or that insufficient space is available on the runway to accommodate landing where rules allow partial blockage/multiple runway occupancy (e.g., land and hold short). In other embodiments, generating a runway taxi clearance advisory comprises determining whether aircraft minimum spacing requirements and runway blockage constraints are satisfied for a pending runway taxi crossing aircraft or other vehicle.

[0016] In some embodiments, determining minimum spacing requirements for a pending runway taxi crossing aircraft or other vehicle are satisfied comprises comparing a current position of a pending runway taxi crossing aircraft or other vehicle for the runway with a current position of successor landing aircraft on the same runway and crossing runways, and determining that time spacing and distance spacing between the current position of the pending runway taxi crossing aircraft or other vehicle and the current position of successor landing aircraft exceeds aircraft minimum spacing requirements.

[0017] In some embodiments, determining runway blockage constraints for a pending runway taxi crossing aircraft or other vehicle are satisfied comprises determining that no part of the runway and runway-exit taxiways to be traversed are blocked at or forward of the current position of the pending taxi aircraft or other vehicle. In other embodiments, generating a runway taxi clearance advisory for a pending runway taxi aircraft or other vehicle along a segment of runway on a current non-arrival runway comprises determining that runway blockage constraints are satisfied for the pending runway taxi aircraft or other vehicle along the segment of runway on the non-arrival runway.

[0018] In some embodiments, determining runway blockage constraints are satisfied for taxiing on the segment of runway on the non-arrival runway comprises determining that the runway segment is not being used by landing aircraft and that no part of the assigned runway and runway-exit taxiways to be traversed is blocked at or forward of the current position of the pending taxi aircraft or other vehicle. In other embodiments, generating preemptive runway taxi crossing clearances further comprises determining that runway blockage constraints are satisfied for the first pending taxi aircraft or other vehicle in the queue and at least one subsequent pending taxi aircraft or other vehicle in the queue. [0019] In some embodiments, determining whether runway blockage constraints for the first pending taxi aircraft or other vehicle in the queue comprises

determining that no part of the assigned runway and runway-exit taxiway to be traversed is blocked at or forward of the current position of the first pending taxi aircraft or other vehicle. In other embodiments, satisfying runway blockage constraints for a subsequent queued taxi aircraft or other vehicle comprises determining that the taxi crossing clearance advisory has been generated for the first pending taxi aircraft or other vehicle in the queue and no part of the assigned runway-exit taxiways to be traversed is blocked at or forward of the current position of the at least one subsequent pending taxi aircraft or other vehicle.

[0020] In some embodiments, aircraft minimum spacing requirements are dependent on the level of visual meteorological conditions (VMC) or instrument meteorological conditions (IMC) that are in effect.

[0021] According to a second aspect of the present invention, there is provided a method for providing clearances for managing vehicle movement on a runway at an airport, the method comprising receiving airport infrastructure information comprising status of airport runways, taxiways, airspace fixes and route procedures, operating parameters and traffic restrictions, receiving an assigned path for each aircraft and other vehicle moving on an airport surface, determining a current position for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport, wherein current position and assigned path for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport is determined in response to frequently occurring events. The method including receiving traffic control advisories and instructions issued by traffic controllers, updating a runway system blockage status, generating an initiate missed approach instruction advisory for a pending landing aircraft if runway blockage is present on the runway when the pending landing aircraft is crossing or has crossed a user-defined missed approach point at the current instant, and communicating to a traffic controller the initiate missed approach advisory that includes instructions for the pending landing aircraft to abort landing on the runway. The method including generating a preemptive runway taxi crossing clearance advisory for taxiing aircraft or other vehicles in a queue when a number of taxiing aircraft or other vehicles in the queue exceeds a user-defined limit, communicating to the traffic controller the preemptive runway taxi crossing clearance advisory that includes instructions for one or more aircraft or other vehicles to proceed across or along a segment of a runway, generating a runway takeoff clearance advisory for a pending departure aircraft that is either next in line to enter the runway for takeoff, or is currently positioned on the runway ready to takeoff when no part of the runway to be traversed is blocked at or forward of the current position of the pending takeoff aircraft, and communicating to the traffic controller the runway takeoff clearance that includes instructions for the pending departure aircraft to proceed to takeoff on the runway.

[0022] In some embodiments of the present invention, the frequently occurring events comprise at least one of a requested runway entry event, a runway exit event, a taxiway intersection crossing event, a runway intersection crossing event, an airspace fix crossing event, and invocation by an external function event.

Brief Description of the Drawings

[0023] For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description for practicing the inventions, read in conjunction with the accompanying drawings in which:

[0024] Fig. 1 shows an example of generic runway landing, takeoff and taxi operations by aircraft and other vehicles in composite form that are included in clearance/instruction advisories in one embodiment of the present invention;

[0025] Fig. 2 shows the inputs and outputs to one embodiment of the present invention;

[0026] Fig. 3 depicts one embodiment of the present invention as part of an automated airport traffic control system;

[0027] Fig. 4 shows one embodiment of the present invention as a decision support tool within an automated surface traffic control system; [0028] Fig. 5 shows the functional components of the process for one

embodiment of the present invention used as a decision support tool within an automated surface traffic control system and software module within a real-time or fast-time computer simulation;

[0029] Fig. 6 shows an example of runway blockages by aircraft and other vehicle operations that cause generation of missed approach instruction advisories in composite form in one embodiment of the present invention;

[0030] Fig. 7 shows an example of pending runway landing, takeoff and taxi operations by aircraft and other vehicles in composite form, where a pending operation is defined as the next operation in line ready to use the runway (i.e., the vehicle at the head of a queue) in one embodiment of the present invention;

[0031] Fig. 8 shows an example of generic landing, takeoff and runway taxi operations by aircraft and other vehicles in composite form that are factors in determining blockage and minimum spacing requirements for generating clearance/instruction advisories in one embodiment of the present invention;

[0032] Fig. 9 shows an example of the application of minimum spacing requirements for generating runway takeoff clearance in one embodiment of the present invention;

[0033] Fig. 10 shows an example of the application of minimum spacing requirements for generating runway taxi crossing clearance advisories in one embodiment of the present invention;

[0034] Fig. 11 shows one embodiment of the present invention as a software module within a fast-time or real-time computer simulation;

[0035] Fig. 12 shows an example of the overall functional process for updating the runway system blockage state for aircraft and other vehicles in one embodiment of the present invention;

[0036] Fig.13 shows an example of the functional process for Updating the Runway System Blockage State for a Nominal Operation in one embodiment of the present invention; [0037] Fig. 14 shows an example of the functional process for updating the runway system blockage state for a departure aircraft in one embodiment of the present invention;

[0038] Fig. 15 shows an example of the functional process for updating the runway system blockage state for an arrival aircraft in one embodiment of the present invention;

[0039] Fig. 16 shows an example of the functional process for updating the runway system blockage state for a runway taxi aircraft and other vehicles in one embodiment of the present invention;

[0040] Fig. 17 shows an example of the functional process for updating the runway system blockage state for a non-nominal operation in one embodiment of the present invention;

[0041] Fig. 18 shows an example of the functional process for issuing initiate missed approach instruction advisories in one embodiment of the present invention;

[0042] Fig. 19 shows an example of the overall functional process for developing preemptive runway taxi clearance advisories for pending aircraft and other vehicles in one embodiment of the present invention;

[0043] Fig. 20 shows an example of the functional process for determining the need for generating preemptive runway taxi clearance advisories in one

embodiment of the present invention;

[0044] Fig. 21 shows an example of the functional process for generating preemptive runway taxi clearance advisories in one embodiment of the present invention;

[0045] Fig. 22 shows an example of the functional process for generating preemptive runway taxi clearance advisories for queued aircraft and other vehicles in one embodiment of the present invention;

[0046] Fig. 23 shows an example of the overall functional process for generating takeoff clearance advisories for pending next departure aircraft in one embodiment of the present invention; [0047] Fig. 24 shows an example of the functional process for identifying departure aircraft eligible for takeoff in one embodiment of the present invention;

[0048] Fig. 25 shows an example of the functional process for generating takeoff clearance advisories in one embodiment of the present invention;

[0049] Fig. 26 shows an example of the overall functional process for generating runway taxi clearance advisories for aircraft and other vehicles in one embodiment of the present invention;

[0050] Fig. 27 shows an example of the functional process for generating runway taxi clearance advisories for taxiing across a runway in one embodiment of the present invention; and

[0051] Fig. 28 shows an example of the functional process for generating runway taxi clearance advisories for taxiing along runways in one embodiment of the present invention.

Detailed Description of the Invention

[0052] Runway traffic controllers issue takeoff, landing and taxi

clearances/instructions to aircraft and other vehicles. Plans for future air traffic management systems rely on the development of automated innovations to better integrate terminal area operations to promote safety and reduce delay. The present invention provides a system and method for runway traffic controllers to identify valid clearances/instructions that comply with complicated runway system operating rules and procedures.

[0053] More specifically, the present invention provides a means to more efficiently manage and resolve runway traffic congestion to improve traffic throughput and reduce delays and emissions by providing more efficient sequencing and timing of takeoffs and landings. The system and method of the present invention receives position and route path data for aircraft and vehicles on the airport surface and in the airspace proximate to the airport, determines which aircraft and vehicle movements will effectively use the airport runways for runway takeoff, landings and taxi operations while ensuring proper separation among the aircraft and vehicles, averting blockages due to runway occupancy by aircraft and vehicles, and generating appropriate advisories (i.e., clearances and instructions) to runway traffic controllers.

[0054] The system and method of the present invention also supports more efficient airspace routings with increased runway throughput, expanding the coordination among controllers at adjacent airports and more efficient sequencing and timing of takeoffs and landings. In support of these objectives, the Runway Clearance Advisor of the present invention (hereinafter Advisor) provides an automated mechanism for generating and presenting runway clearance advisories to controllers that accurately implement spacing rules and obstruction/blockage constraints, thereby mitigating the possibility of occurrences of delays and spacing errors due to mental miscalculations.

[0055] The meaning of the following terms as used herein with respect to the Advisor is as discussed in the following paragraphs:

[0056] A "minimum spacing requirement" is the sum of a minimum separation requirement and a spacing buffer, both specified by the user of the Advisor.

Minimum separation requirements represent standardized rules applicable between two aircraft operating on the same runway or a pair of interacting runways, where the runways may be at one airport or at two different airports. The user defines leader-follower aircraft-type dependent minimum separation matrices for various runway configurations and procedures, including operations during various levels of visual and instrument meteorological conditions. The Advisor applies spacing requirements in time or distance units or both per user specification. For example, successive aircraft departing a runway may have a 2 minute separation requirement, but aircraft under radar control on departure courses diverging by at least 15 degrees may only have a 1-mile minimum separation requirement. By general practice, minimum time spacing is applied to the times aircraft cross/block their runway start thresholds. Two runways may operate independently of each other (e.g., dual parallel runways if at least 4300 feet apart), in which case the Advisor applies no minimum spacing requirement to the aircraft. Two runways at different airports are normally treated as independent operations with respect to minimum spacing requirements. However the Advisor can treat operations on runways at two or more different airports as dependent based on user-defined cross-airport runway interaction rules. In addition, the Advisor enables the user to specify special spacing procedures that permit simultaneous use of a runway for landing or takeoff when specified spacing exists with a predecessor moving along the runway. For example, the user may specify minimum spacing requirements compliant with existing daylight operating rules or with a concept of future operations allowing multiple takeoff/landing operations simultaneously on a runway.

[0057] "Runway blockage" is an event that prevents the use of a runway.

Runway blockage occurs when a runway, runway section or runway intersection (i.e., runway-taxiway and runway-runway intersections, including virtual intersections along runway centerline extensions) is occupied by or dedicated to another aircraft or other vehicle. If an aircraft is cleared to use a runway, the Advisor dedicates the part of the runway that the aircraft will traverse to that aircraft. For example, the Advisor would not generate a takeoff clearance advisory to a pending departure aircraft if the runway to be traversed is occupied by another aircraft or other vehicle or if an intersection with a crossing runway is dedicated to another aircraft. For aircraft approaching the runway to land, the Advisor dedicates use of the runway to the approaching aircraft at the instant the aircraft reaches a standard decision point along its final approach to the runway. As an aircraft moves along the runway, the Advisor releases/opens the runway segment vacated by the aircraft for use by another aircraft or other vehicle. The Advisor makes an intersection available to an aircraft landing or taking-off on a crossing runway or an aircraft taxiing across the runway, subject to compliance with minimum spacing requirements. With respect to arrivals, the Advisor determines a missed approach is necessary if the landing runway is occupied (runway blocked), subject to user- specified optional special/day light spacing rules. The Advisor does not generate missed approach advisories due to inter-aircraft spacing violations, navigation errors or procedural anomalies. The Advisor can also allow taxiing on a segment of a runway, typically an inactive runway, per user option.

[0058] "Externally-derived constraints" occur when traffic situations not directly related to the immediate runway operation impose delays or diversions to runway operations. The Advisor typically implements these externally-derived constraints as takeoff time restrictions, which require the aircraft to takeoff at or after the indicated time or during a specified time window. The Advisor may generate the takeoff time restriction based on available traffic information or may receive the takeoff time restriction from an external air traffic control or traffic flow

management function. Typically externally-derived constraints primarily affect aircraft departures. Application of takeoff time restrictions to meet departure fix spacing rules is an example of externally-derived constraint that affects runway departures. For example, the Advisor may apply user-defined minimum spacing requirements between successive takeoffs destined to a common departure fix in the airspace. The Advisor applies a takeoff time restriction to the second aircraft that enables subsequent proper airspace spacing at the departure fix and avoids an airspace overtake conflict between the two aircraft having different flight characteristics. Alternatively, the Advisor may receive a takeoff time restriction from an external function to accommodate departure fix spacing with aircraft from another airport that are using the same departure fix; or the restriction may be due to miles-in-trail or time-based metering spacing procedures at any fix. The Advisor will generate a takeoff clearance advisory at the earliest instant at or after the restricted time at which the aircraft is compliant with minimum spacing

requirements and runway blockage constraints.

[0059] In each embodiment, the Advisor maintains data according to the following definitions of aircraft operational mode applicable at the current instant:

[0060] Pending next landing aircraft: an arrival aircraft on final approach to a runway that is next to land on that runway but could require a missed approach instruction; by standard practice the aircraft has previously received an actual landing clearance. [0061] Pending next takeoff aircraft: a departure aircraft on a unique surface path to a runway that is the next aircraft in line ready to enter the runway and begin takeoff, or is positioned on the runway ready to begin takeoff; the aircraft has not yet received an actual takeoff clearance.

[0062] Pending next runway taxiing aircraft: a taxiing aircraft ready to enter and cross a runway or taxi along a segment of a runway; the aircraft has not yet received an actual runway taxi clearance.

[0063] Pending queued runway taxiing aircraft: a runway taxiing aircraft queued behind another runway taxiing aircraft at a runway intersection; the aircraft has not yet received an actual runway taxi clearance.

[0064] Current runway aircraft: an arrival aircraft on a runway, or a departure aircraft actually cleared to a takeoff, or a taxiing aircraft actually cleared to taxi on the runway.

[0065] Current missed approach aircraft: an arrival aircraft actually executing a missed approach for a runway per controller instruction.

[0066] Recent departure aircraft: the most recent aircraft actually to takeoff from a runway that is within a user-defined distance (e.g., 5 nmi) of the airport reference point.

[0067] Other vehicle: any non-aircraft vehicle active on the airport at the current instant.

[0068] The process of the system and method of the present invention

automatically and continually updates the generated runway clearance advisories based on inputs that are refreshed at regular but short time intervals (e.g., every second) or in response to frequently occurring events (e.g., at a requested runway entry and actual runway exit event, taxiway or runway intersection crossing and airspace fix crossing events; or when invoked by an external function). In one embodiment, a new set of advisories is automatically updated at least once every thirty seconds. In yet another embodiment, the new set of advisories is

automatically updated at a rate of at least ten hertz. The process of the system and method of the present invention can also be initiated manually by a runway traffic controller or other authorized person. In one embodiment, a completely new set of advisories is generated for each update cycle. In another embodiment, only advisories that are new or have changed are generated for each update cycle.

[0069] As shown in Fig. 1, the runway controller manages runway landing, takeoff and runway taxi operations. Fig. 1 is a composite depiction of each type of runway operation; these runway operations would not occur simultaneously on a runway. The position of arrival aircraft 1 at runway entry is shown at the left end of the runway (runway entry) and at runway exit, departure aircraft 2 at runway exit, taxiing aircraft or other vehicle 3 at runway entry and exit after taxiing across the runway, and taxiing aircraft or other vehicle 4 at runway entry and exit after taxiing along the runway are depicted in Fig. 1.

[0070] The Advisor determines if a runway takeoff or taxi operation can be initiated or a landing operation should continue at the current instant subject to operating rules and procedures, the current and projected state of aircraft traffic, and descriptors of airport and local airspace geometric structures and environmental conditions, as shown in Fig. 2. The Advisor's decision logic fits departures between arrivals and other departures and fits runway taxi operations between arrivals and departures so as to comply with runway inter-aircraft spacing requirements, constraints due to runway blockages by other operations and constraints due to airspace traffic situations.

[0071] The Advisor is a transformative process that uses aircraft and vehicle position and path inputs to determine aircraft and vehicle movements that ensure proper separation among the aircraft and vehicles and prevents the aircraft and vehicles from obstructing each other and then generates appropriate runway clearance advisories to runway controllers. These advisories are recommended instructions for aircraft to commence takeoff on a runway or for aircraft or other vehicles to commence taxiing across or along a runway. The runway clearance advisories are provided to runway traffic controllers for issuance as actual instructions to aircraft or other vehicles subject to runway traffic controller discretion. The Advisor recommends aircraft movement runway clearance advisories for use by runway system traffic controllers at a single airport or at multiple integrated airports.

[0072] As shown in Fig. 2, in this embodiment, the Advisor continually receives traffic surveillance data, meteorological data, information defining airport and airspace configurations, and current operating plans, procedures and constraints. The Advisor continually receives additional data from external support functions identifying clearances and instructions that have been actually issued by controllers (as well as estimated/projected runway entry and exit times if needed for time spacing analysis). At the current instant, defined by the time step interval or event occurrence, the Advisor processes the data and generates clearance and instruction advisories. The process is repeated at the each subsequent time step or event.

[0073] In Fig. 2, the Advisor comprises one or more software programs running on a computer having at least a 32-bit architecture with a minimum speed of 2 GHz and having access to at least 2 GB of memory. In one embodiment, the Advisor is a modular component of an advanced automated airport traffic control system. In another embodiment, the Advisor is a modular component of a fast-time or realtime computer simulation of advanced automated surface traffic control systems. This real-time mode may be implemented as part of an actual air traffic control operation at an airport or within a human-in-the-loop laboratory simulation.

Alternatively, the Advisor may be implemented as part of a fast-time simulation of air traffic operations. Hence, the mechanism by which the Advisor receives updates of traffic state and actual clearances and instruction depends upon the implementation environment (e.g. updates may be provided by auxiliary

automation in an actual operation or by messaging within a simulation).

[0074] Apart from missed-approach interventions, the Advisor does not apply advisory control to landings because arrival operations are dependent on decisions made by external airspace controllers. The Advisor provides recommendations to the runway traffic controller to issue takeoff clearances, taxi entry and path clearances, and missed-approach initiation (due to runway blockage) instructions at the current instant. The Advisor reassesses the traffic situation according to its update protocol (e.g., once per time step or traffic event) and issues new and updated advisories.

[0075] While a runway traffic controller also issues landing clearances to aircraft on final approach, landing clearances are outside the scope of the Advisor because the aircraft sequence and spacing has been largely pre-determined by the airspace controller and the aircraft are committed to the landing runway.

[0076] Fig. 3 illustrates one embodiment of the Advisor as an integrated hardware/software component of a generic advanced automated airport traffic control system. Several different automated systems, including the Tower Fight Data Manager (TFDM) and Advanced Surface Movement Guidance and Control Systems (A-SMGCS), are currently at different stages of development,

implementation and operation. The automated airport traffic control systems are supported by or include auxiliary systems or sub-systems that provide surveillance, fight plan, meteorological, traffic flow constraints and associated data. The automated systems also incorporate computerized decision support tools, operating as sub-systems within the automated system.

[0077] In Fig. 3, the Advisor comprises software programs running on a computer having at least a 32-bit architecture with a minimum speed of 2 GHz having access to at least 2 GB of memory. In some of these embodiments, the computer 10 receives data form airport/airspace surveillance systems 20, such as Airport Surface Detection Equipment-Version X (ASDE-X), Airport Surveillance Radar (ASR) and Automatic Dependent Surveillance - Broadcast (ADS-B), as well as automated airport traffic control systems 30, which may include other decision support tools (DSTs), and other airport operations systems, such as flight operations and associated infrastructure data 35, weather data 36, and local operations adaptation data repository 37, as shown in Fig. 3. In another

embodiment, the Advisor is a hardware/software decision support tool sub-system of the automated airport traffic control system.

[0078] The Advisor processes vehicle state inputs provided by surveillance sources, runway assignment inputs provided by other decision support tools, issued traffic control advisories/instructions and restrictions and airport surface and airspace network system infrastructure inputs maintained by the automated system that define the physical parameters for analyzing the airport traffic situation. Given the above inputs, the Advisor generates runway clearance advisories that are provided to runway traffic controllers. In the embodiment shown in Fig. 3, input data describes the current position of vehicles and runway and path assignments and airport/airspace infrastructure components (runways, taxiway crossings, airspace fixes and route procedures and operating parameters). The Advisor processes the input data and generates runway takeoff and taxi clearance advisories for aircraft and vehicles and missed approach instruction advisories for aircraft that are provided to runway traffic controllers. In some embodiments, the automated airport traffic control systems have interface sub-systems that provide the runway clearance advisories to traffic controllers.

[0079] Fig. 4 illustrates an embodiment of the Advisor that comprises a dedicated computer 10 executing the Advisor software that can operate as a standalone system or as part of an automated airport traffic control system comprising surveillance and communication equipment and software/hardware components. In this embodiment, the computer 10 running the Advisor software receives input data from the airport/airspace surveillance systems 20, advanced airport automated traffic control subsystem 32, such as a configuration of TFDM decision support tools, and local operations adaptation data repository 37, as shown in Fig. 4. For example, airport/airspace surveillance systems 20, such as ASDE-X, ASR and ADS-B systems, provide surface and airspace surveillance data describing the state of aircraft and other vehicles. The local adaptations data repository 37 compiles and provides airport and airspace infrastructure data including flight plan and aircraft descriptors, runways and taxiway configurations, airspace arrival and departure routings and fixes, runway assignment rules, minimum separation requirements and associated procedural requirements. The advanced airport automated traffic control subsystem 32 includes decision support tools that monitor the current state of aircraft and other vehicles and controller actions (e.g., actual issuance of clearances and instructions), exchange data with other DSTs and external air traffic management systems, and provide the resultant data to the Advisor and receive updated data from the Advisor. The other DSTs track the position and intent of surface and airspace aircraft and other vehicles, predict aircraft and vehicle trajectories, identify runway assignments, guide vehicle movement by processing turn, speed, acceleration / deceleration, and hold and clearance advisories or instructions, process and disseminate traffic restrictions and perform related traffic management functions. The Advisor integrates selected inputs from the other DSTs, airport/airspace surveillance systems 20 and local adaptations data repository 37 and generates runway clearance and missed approach advisories for presentation to runway traffic controllers.

[0080] In most embodiments, the Advisor's inputs describing vehicle movement are limited to aircraft and other vehicle position and assigned/planned path data, including runway assignment, and applicable traffic restrictions. Other inputs are limited to infrastructure descriptions of the surface and airspace network route structure, applicable minimum spacing requirements for aircraft and other vehicles and airport/airspace operating parameters. The assignment of runways and paths as well as modification and scheduling of runway operations and movement along paths is outside the scope of the present invention. Runway and path traversal assignments are determined external to the Advisor by controllers based on prescribed or preferred procedural rules or based on optimization advisories provided by external decision support tools in an automated traffic control system/DST. Similarly, optimized time schedules or time-based trajectory predictions for path traversals are the product of external decision support tools. Regardless of current operations or future more-automated operations, the Advisor processes position, path-to/from-runway descriptors and traffic restrictions and determines runway advisories without regard to scheduling and other route information. Apart from missed approach advisories, the Advisor determines runway clearance advisories without otherwise changing assigned/planned paths and runways in any manner. In each embodiment, the Advisor examines aircraft minimum spacing requirements, runway blockage and externally-derived constraints as part of the process to determine valid runway movement advisories at the current time.

[0081] In one embodiment, the Advisor determines and issues advisories to traffic controllers recommending takeoff and runway taxi clearances and abort landing/initiate missed approach instructions by performing the functional process shown in Fig. 5. In this embodiment, the overall functional process follows a hierarchy in which landings by arrival aircraft have precedence over other runway operations. After updating the runway system blockage status, the Advisor determines whether any pending landing aircraft needs to abort their landings due to runway blockage. When an aircraft landing needs to be aborted, the Advisor issues an advisory to initiate a missed approach, as shown in Fig. 5. The Advisor then determines whether to issue any preemptive runway taxi crossing clearances to allow aircraft or other vehicles to taxi across a runway to alleviate airport surface congestion. These taxi crossing clearances would preempt takeoff and other runway taxi operation. In this embodiment, the Advisor then determines and issues takeoff clearances based on runway blockage, inter-aircraft minimum spacing requirements and externally-derived traffic constraints. The Advisor would then determine and issue runway taxi clearance advisories based on runway blockage, inter-aircraft minimum spacing requirements and externally- derived traffic constraints.

[0082] While the runway system blockage update is a data maintenance function in the Advisor, this function is included as a basic component of the Advisor because calculations are required to interpret the current state of the runway(s) and each component of the Advisor may issue advisories that alter the projected runway blockage state during the current instant, as shown in Fig. 5. Unlike minimum spacing requirements, which remain static within an update session/cycle, projected runway blockage conditions change as advisories are issued by each component of the Advisor. For example, with reference to Fig. 6, advisories generated for takeoff and runway taxi movement clearances are continuously issued to the runway controller and simultaneously fed back to the runway system blockage update component. This feedback enables dynamic renewal of blockage information so that each component can properly determine and issue advisories based on the latest generated advisories, including advisories previously issued by the Advisor during the current update session/cycle.

[0083] The following paragraphs summarize the function of each component shown in Fig. 5.

[0084] Update Runway System Blockage State ~ At the start of each assessment update session/cycle (i.e., the current instant), the Advisor conducts an initial blockage update based on the current traffic situation at the current instant. The Advisor uses received current traffic surveillance data and reports of

clearances/instructions issued by controllers to determine the current traffic situation. The Advisor uses these data, together with descriptors of airport and airspace structures and procedures, to interpret aircraft position and intent information to determine the runway ownership span of each aircraft or other vehicle actually cleared to move on the runway system, some of which are currently moving on the runway system. The runway nominal ownership span of an aircraft or other vehicle defines the portion of the runway that is blocked (i.e., not available) for use by other aircraft at the current instant. The aircraft or other vehicle is considered a blockage factor by the Advisor if it currently is on or over the runway, on approach to the runway or in close proximity to the runway. For each aircraft and other vehicle moving on or over a runway or cleared to do so, the Advisor designates that part of the runway at and portions of the runway forward (ahead/downstream) of the aircraft's current position as being blocked. In the case of a departure aircraft positioned on the runway but not yet cleared to takeoff, the runway segment occupied by the aircraft is designated as blocked. In the case of special non-nominal flights/operations (i.e., emergency, security-sensitive, etc.), the Advisor blocks the entire runway or runways regardless of the current position of the aircraft or other vehicle. [0085] Once the runway system blockage state is established at the start of an assessment update, the other components of the Advisor shown in Fig. 5 are provided the updated runway system blockage state and may continually issue advisories. Each of the advisories actually issued by traffic controllers for an individual aircraft or other vehicle are also provided to the Update Runway System Blockage Component of the Advisor, as shown in Fig. 5. The Update Runway System Blockage Component of the Advisor then determines any new runway blockage states based on the new advisory, and provides the updated runway system blockage state to the invoking component. The invoking component then generates its next new advisory based on the updated runway system blockage state. The latest updated runway system blockage state is also provided to each component of the Advisor at its commencement.

[0086] Issue Initiate Missed Approach Instruction Advisory (if required for Landing Aircraft) - This component of the Advisor issues a missed approach instruction advisory to the runway traffic controller for an inbound arrival aircraft that is on the final approach to or over a landing runway. The inbound arrival aircraft previously would have been issued an actual landing clearance by a controller. This component of the Advisor determines whether the user-defined criteria for a missed approach condition have been met for an inbound arrival aircraft that is crossing or has crossed a user-defined missed approach decision point at the current instant. This decision point may be defined by a point on the final approach course, a distance from the runway or a height above ground by aircraft category. The Advisor identifies a missed approach condition if the arrival aircraft's landing runway is blocked at this instant by aircraft or other vehicles and issues a missed approach instruction advisory to the runway controller.

[0087] Fig. 6 illustrates various generic blocking conditions that cause a missed approach instruction advisory to be generated for arrival aircraft 1. Fig. 6 is a composite depiction of each type of runway operation; these would not occur simultaneously on a runway. In Fig. 6, blockage of the landing runway may be due to occupancy of the runway at the current instant by preceding landing aircraft 2, takeoff aircraft 3, taxiing aircraft or other vehicle 4, or a runway intersection being dedicated to an aircraft or other vehicle 5 operating on a crossing runway.

[0088] The Advisor also provides a user option, by means of specification of clearance advisory decision rules that mitigates blockage constraints to allow landings when the runway is blocked if special procedures are in effect. These user-specified procedures include landings that hold short of crossing runways and special daylight/advanced technology spacing rules that allow multiple

simultaneous runway occupants. When special procedures are in effect, the aircraft landing is allowed if the length of the unblocked portion of the runway from the entry threshold, is sufficient for the aircraft to safely land and comply with the applicable allowed minimum spacing requirements, and all operational conditions required for this special procedure are satisfied. The Advisor issues an initiate missed approach instruction advisory to runway traffic controllers without invoking the update runway system blockage component of the Advisor to perform a runway blockage status update. Updating the runway system blockage state in response to this newly generated advisory is not necessary because the prior runway system blockage state have assigned blockages for each arrival aircraft on or above the runway at the current instant. With respect to approaching aircraft, updating the runway system blockage state is not warranted for aircraft not occupying the runway system.

[0089] At each advisory assessment update session/cycle, the Advisor receives traffic surveillance data for arrival aircraft executing a missed approach to enable application of inter-aircraft minimum spacing requirements until that aircraft is no longer a factor for runway operations.

[0090] Issue Preemptive Runway Taxi Crossing Clearance Advisory ~ This component of the Advisor issues preemptive clearance advisories for queued taxiing aircraft to follow a preceding taxiing aircraft across a runway currently used exclusively for departures (i.e., a runway not in immediate use by arrivals) when the queue size of aircraft and other vehicles waiting for clearance to taxi across a runway exceeds user-specified limits. The preemptive clearance advisories allow a stream of aircraft and other vehicles to taxi across a runway intersection, blocking use of the intersection for takeoffs and other taxiing aircraft and other vehicles at the current instant and for the duration of the stream of aircraft for which taxi crossing clearance has been issued, when the runway controller actually issues the Advisor generated runway taxi crossing advisories. Again, because of coordination complexities on runways actively being used for landings, the Advisor does not provide preemptive taxiing along runway advisories.

[0091] Issue Takeoff Clearance Advisory (for Departure Aircraft) -- This component of the Advisor will issue a takeoff clearance advisory to the runway controller only for a departure aircraft that is either the next aircraft in line ready to enter the runway and immediately begin takeoff, or is currently positioned on the runway ready to begin takeoff immediately. In either case, this aircraft has not yet actually been issued a takeoff clearance by a runway traffic controller. For example, multiple taxiways may be feeding departures to a single runway and the first aircraft in the departure queues at each of these taxiways are competing for takeoff clearance at the current instant. These aircraft may also be at or on different runways and able to takeoff at the same time, or may be competing for the same runway entry point.

[0092] Fig. 7 illustrates pending operations where departure aircraft and taxiing aircraft or other vehicles are competing for runway clearance at the current instant on the same runway. Each pending aircraft is the first aircraft in its queue and is a candidate for the next takeoff from this runway. In Fig. 7, three pending departure aircraft 2, 3 and 4 compete for takeoff clearance. Aircraft 2 and 3 are in separate taxiway paths to the runway and are competing for runway entry at a common entry point at the runway threshold, while aircraft 4, the third pending departure aircraft, is at a different taxiway intersection entry point to the same runway. Other departure aircraft queued behind these pending takeoff aircraft are not part of the current update session/cycle of this component of the Advisor. This is due in part to the fact that takeoff queue data is not provided for queued aircraft and because of the coordination complexities with airspace controllers, the Advisor is not designed to preempt (i.e., delay) aircraft landings to alleviate excessive takeoff queue congestion.

[0093] After the Advisor processes updates to determine the current runway and taxiway traffic state, this component of the Advisor determines the eligibility of each aircraft for takeoff clearance issuance. The Advisor first determines if the departure aircraft is not subject to delay in order to meet a takeoff time restriction due to an externally- derived constraint. Then the Advisor separately determines each aircraft's eligibility with respect to both runway blockage and minimum spacing requirements relative to aircraft and other vehicles that have been previously cleared to use the runway. These include aircraft and other vehicles that are currently standing on or moving toward the runway surface, are executing a missed approach over the runway, are on final approach and near the threshold of the runway, or have recently departed the runway, as shown in Fig. 8. Fig. 8 is a composite depiction of different aircraft situations; these would not occur simultaneously on a runway. The set of currently cleared generic operations shown in Fig. 8 are factors for runway blockage and aircraft minimum spacing

requirements that could block a successor operation.

[0094] In Fig. 8, runway blockage would be caused by arrival aircraft 1 being on or over the runway, departure aircraft 2 being cleared to enter the runway and takeoff, departure aircraft 3 being on or at low altitude over the runway, missed approach aircraft 4 being over the runway area, taxiing aircraft or other vehicle 5 crossing the runway, taxiing aircraft or other vehicle 6 moving along the runway, and taxiing aircraft or other vehicle 7 being cleared to enter and move across the runway. While arrival aircraft 8 is on final approach and departure aircraft 9 is beyond the departure end of the runway, both are in the airspace, not on or over the runway, and hence are not part of runway blockage assessment of this component of the Advisor. Aircraft 8 and Aircraft 9 are factors in the assessment of aircraft minimum spacing requirements, which, apart from runway blockage, also prevents runway use by other aircraft and other vehicles. [0095] The Advisor determines if the departure aircraft could immediately takeoff without being blocked by current runway users. The generic blockage examples shown in Fig. 6 for missed approaches also apply to takeoff aircraft. The Advisor determines if the departure aircraft can immediately takeoff without violating minimum time and distance spacing requirements with previous landings and takeoffs (i.e., predecessors) on all interacting runways as well as with the next incoming landing aircraft (i.e., successors) on all interacting runways. Fig. 9 illustrates an example in which a pending takeoff aircraft 1 is eligible for takeoff clearance at the current instant because required minimum distance spacing exists with all pending (incoming) next landing aircraft 2 and 3 (which are successor aircraft) and required minimum time spacing exists with recent takeoff aircraft 4 (which is predecessor aircraft) as long as runway blockage and externally-derived constraints are also satisfied. The aircraft minimum spacing requirements may be specified by the user as a time or distance to/from each operation's runway entry threshold, taking into account that the official requirement may be defined as a spacing from the point at which aircraft paths converge (e.g., a taxiway-taxiway intersection, runway-taxiway intersection).

[0096] At this point, the processing of the Advisor has identified the set of aircraft that could take off at the current instant independently of each other, but has not determined if any of these aircraft would interfere with other aircraft in this set if issued a takeoff clearance. In one embodiment, the Advisor enables the user to specify one or more special solution routines to determine which of the eligible aircraft should be considered for takeoff clearance advisory assignment and their order of assignment. The takeoff clearance advisories issued by the Advisor are normally subject to the condition that only one takeoff per runway is allowed at the current instant. Such user-specified routines typically are sensitive to local procedures and constraints.

[0097] In one embodiment, the Advisor assigns runway takeoff clearance preferences according to which aircraft has the earliest requested takeoff time. A requested time could be determined by a first-come/first-serve strategy that simply identifies the earliest aircraft actually ready to takeoff on each runway or one that identifies the earliest estimated un-delayed takeoff time for each runway derived from analysis of un-delayed taxi transit from the time of aircraft's actual entry into the airport movement area. In another embodiment, the Advisor applies

optimization routines to assign takeoff clearances. An optimized takeoff plan could be provided by sequencing and scheduling routines that periodically examine traffic loading projected over a window of future time and generate a preferred schedule of landing, takeoff and runway taxi operations using standard algorithmic techniques or heuristic formulations. An external or auxiliary function provides these preferences to the Advisor. If no special solution routines are specified, the Advisor provides a default a solution that selects aircraft for takeoff clearance assignment on each runway and their order using first-come/first-serve requested takeoff time criteria. The result is a preferred order of aircraft potential takeoffs, nominally one per takeoff runway.

[0098] After identifying the preferred aircraft to receive a takeoff clearance advisory and the affected runway, the Advisor issues the takeoff clearance advisory for this aircraft to the runway controller and simultaneously updates the runway system blockage state. The Update Runway System Blockage State component then blocks the runway at and forward (downstream) of the start-of-takeoff position of the aircraft. The Advisor applies the updated runway system blockage state to the next-preferred aircraft waiting for takeoff clearance (e.g., a candidate departure at another runway). If the updated runway system blockage state does not block the next-preferred aircraft waiting for takeoff clearance and aircraft minimum spacing requirements are still satisfied, the Advisor issues a takeoff clearance advisory for this aircraft to the runway controller and again simultaneously updates the runway system blockage state. If the updated runway system blockage state blocks the next-preferred aircraft waiting for takeoff clearance or the aircraft minimum spacing requirements are not satisfied, the Advisor does not issue a takeoff clearance advisory for the next-preferred aircraft waiting for takeoff clearance, and proceeds to examine subsequent aircraft waiting for takeoff clearance. The process of this component of the Advisor iterates through the list of preferred aircraft waiting for takeoff clearance.

[0099] Issue Runway Taxi Clearance Advisory ~ This component of the Advisor issues a runway taxi clearance advisory to taxi across a runway or along a segment of a runway. The runway taxi clearance advisory is issued for an aircraft or other vehicle that is the next aircraft or other vehicle in line and ready to immediately enter the runway, and has not yet actually been issued a taxi clearance. Fig. 7 illustrates two taxiing aircraft or other vehicles 5 and 6 that are waiting clearance to cross the runway at different runway-taxiway intersections and a third aircraft or other vehicle 7 that is queued behind aircraft or other vehicle 6. This queued taxiing aircraft or other vehicle 7 could be cleared at the current instant to follow its predecessor aircraft or other vehicle 6 in taxiing across the runway as part of a preemptive runway taxi clearance process.

[0100] For example, in the case of the next aircraft or other vehicles 5 or 6 that are ready to taxi either across or along a runway, the Advisor determines if this taxi maneuver is possible without violating runway blockage due to landing aircraft, aircraft taking off and taxiing aircraft that have already been issued a clearance by the controllers (some which are actively moving on the runway) or for which the advisor has just issued an advisory as part of its current update session/cycle. The generic blockage examples shown in Fig. 6 for missed approaches also apply to runway taxi aircraft. Furthermore for runway taxi operations, the Advisor requires continual receipt of updates from external functions of Hold (stop) instructions to temporarily restrain taxi movement at runway entry due to blockage on the taxiway system serving the aircraft's runway exit.

[0101] For a runway taxi crossing, such as pending next runway taxi crossing aircraft or other vehicle 1 shown in Fig. 10, the Advisor determines if the crossing operation is possible without violating minimum time or distance spacing requirements with a next incoming landing aircraft 2 to the runway. The Advisor does not examine minimum spacing requirements with takeoff aircraft because taxi-versus-takeoff conflicts are precluded by application of runway blockages for both the taxi across runway and taxi along runway cases. The Advisor also does not consider issuing a runway taxi clearance advisory for aircraft and other vehicles to taxi along a runway actively being used for landings because such operations require complex coordination with airspace controllers, which is outside the scope of the Advisor.

[0102] Upon issuing a runway taxi clearance advisory for taxiing on or along a runway, the Advisor updates the runway system blockage state at the current instant to capture any new projected blockages introduced by the issued runway taxi clearance advisory. Here, the update runway system blockage state component blocks the runway at and forward (downstream) of the aircraft's or other vehicle's start-of-taxi position.

Alternative Embodiments

[0103] The Advisor includes a modular software component that runs on either dedicated or shared computer system resources. In various embodiments, the Advisor is a modular component of the following systems:

an automated airport traffic control system;

a real-time computer simulation system; and

a fast-time computer simulation system.

[0104] In each of these embodiments, the Advisor is intended to operate at a rapid update rate using input data describing a small subset of airport aircraft traffic. At each update instant, the Advisor compiles the latest traffic situation data for only those aircraft or other vehicles that are pending, current or recent runway users. Pending aircraft and vehicles include those that are next in line for a runway takeoff or are candidates to taxi across or along a runway that have not actually been issued a clearance. Other pending aircraft are inbound arrival aircraft that may require missed approaches. The Advisor generates clearance and instruction advisories only for pending aircraft. Since the advisories generated by the Advisor may or may not be implemented by traffic controllers, the Advisor requires immediate updates describing the clearances and instructions actually issued by controllers (which may differ from those recommended by the Advisor). By this means, the Advisor knows at any instant which aircraft are potential subjects for advisory updates versus those that already actually have been issued movement clearances or maneuver instructions.

[0105] Fig. 11 illustrates an embodiment of the Advisor as part of fast-time or real-time computer simulations of automated airport traffic control systems. This embodiment is essentially the same as the embodiment shown in Fig. 4, except that the inputs to computer 10 running the Advisor software are software modules. For example, each of surface/airspace graph state data processor 50, which provides the current airport surface and proximate airspace traffic situation, traffic route planner 55, which provides current assigned route paths and runway assignments, terminal manager 60, which provides current traffic restrictions for modeling coordinated airport and airspace operations, vehicle movement manager 65, which provides issued clearances and instructions for vehicles on the airport surface and proximate airspace, and local operations adaptation data base 70, which provides airport and airspace infrastructure data including flight plan and aircraft descriptors, runways and taxiway configurations, airspace arrival and departure routings and fixes, runaway assignment rules, minimum separation requirements and associated procedural requirement, are software modules that interact through computer data exchanges to provide simulated or previously recorded data, as shown in Fig. 11.

[0106] The fast-time computer simulation mode is implemented to examine the effectiveness of alternative decision support tool algorithms or other operational improvements (e.g., modified separation rules) in meeting design objectives and operational benefits (e.g., potential delay and emissions reduction impacts). The real-time computer simulation mode is implemented as part of a human-in-the-loop laboratory simulation to examine human air traffic controller capabilities when operating with the Advisor and associated decision support tools. The real-time computer simulation mode can also be used to assess the performance and technical capabilities of equipment and components in supporting these operations. [0107] In each embodiment, the Advisor requires the input data to be collected, compiled, analyzed and assembled by external services or auxiliary automation processors. These functions prepare and deliver continual updates of traffic situation as well irregularly-timed updates and static data describing constraints and airport structure, procedures and conditions.

[0108] Basic traffic situation data provided to the Advisor for each pending, current and recent departure aircraft or other vehicles at the current instant include:

runway identity;

runway entry point identity (e.g., runway-taxiway intersection, landing runway threshold or intersection);

aircraft/vehicle identity and type; and

aircraft/vehicle state data (i.e., position, velocity and acceleration).

[0109] Supplemental traffic situation data provided to the Advisor for different types of operations include at least the following.

[0110] For each departure aircraft the supplemental traffic situation data includes:

requested or planned runway takeoff time;

entry queue identity; and

departure fix identity.

[0111] For each pending next runway taxiing aircraft or other vehicle the supplemental traffic situation data includes:

requested or planned runway entry time;

runway exit point identity; and

predicted runway occupancy/transit time.

[0112] For each pending queued runway taxiing aircraft or other vehicle the supplemental traffic situation data includes:

entry queue identity;

current time in queue; and

current queue position. [0113] For each pending next landing aircraft the supplemental traffic situation data includes:

predicted landing runway time (i.e., estimated time of crossing the landing runway threshold) if needed for application of minimum time spacing; and actual time of start and end of runway occupancy by takeoff and landing aircraft and taxi occupancy by aircraft or other vehicles.

[0114] Immediate reports of runway clearances and instructions actually issued by traffic controllers for aircraft and vehicles include the type of runway clearance or instruction (i.e., takeoff clearance, runway taxi movement, missed approach) and relevant content (e.g., runway identity, taxi path, clearance limit).

[0115] Immediate reports of other operational requirements generated by traffic controllers or external functions include:

for pending takeoff aircraft: takeoff time restrictions; and

for runway taxiing aircraft or other vehicles: any Hold instruction to temporarily stop taxi movement at runway entry due to blockage on the taxiway system serving the aircraft's runway exit.

[0116] Asynchronous updates of airport operations include:

meteorological conditions; and

traffic plan defining active runway configuration.

[0117] Static data includes:

Computationally-based descriptor of airport and local airspace geometric structures (e.g., network edge/vertex graph with grid points, or system of polygons defining runway and taxiway segments and intersections and airspace routes and fixes);

Missed approach decision point parameters;

Minimum separation requirements and buffers (time/distance) descriptors for each traffic plan; and

Special operational parameters such as:

Runway spacing rule for successive takeoffs destined to a common departure fix; Limit on queue size for runway-taxiing aircraft

awaiting runway entry; and

Scope of airspace coverage for traffic situation

monitoring.

[0118] Different embodiments are discussed in the following sections. Each of these embodiments receives data and generates runway clearance, takeoff and missed approach advisories to the runway controller.

Automated Airport Traffic Control System Embodiment

[0119] In this embodiment, the Advisor is a hardware/software decision support tool within an automated airport traffic control system, as shown in Fig. 3. In this embodiment, the Advisor generates advisories by applying the solution process shown in Fig. 5 at each invocation. Given the identity and state of each aircraft and actual traffic control clearances/instructions in effect at the current instant as inputs, the Advisor treats each pending aircraft as eligible for issuance of an advisory. The Advisor then launches a series of computational operations to update the blockage data and determine and issue advisories to runway controllers for aircraft qualifying for clearances and instructions. In this embodiment, the methodology of the Advisor performs the following steps:

[0120] Update Runway System Blockage State - This component is invoked initially at the start of each advisory assessment session/cycle at a current instant and subsequently is invoked in response to each generation of a new advisory for a single aircraft or other vehicle by another component as part of the current session, as shown in Fig. 12. The Advisor first determines whether the invocation of this component is in response to an initial blockage update at session start-up or in response to a newly-generated advisory for an aircraft or other vehicle. For an initial blockage update at session startup, the Advisor reviews the current state of each vehicle and determines whether that vehicle is conducting a nominal or non- nominal (emergency, security-sensitive and the like) operation. For nominal operations, the Advisor executes the update runway system blockage state for nominal operations for the initial blockage update at session startup as well as for a blockage update in response to a newly-generated advisory. Otherwise, the update runway system blockage state for non-nominal operations is executed.

[0121] For each nominal operation, the Advisor executes a specific update runway system blockage state for nominal operations process depending on whether the operation is being conducted by a departure or arrival aircraft or a runway taxi aircraft or other vehicle, as shown in Fig. 13 and discussed in more detail in the following paragraphs.

[0122] For a departure aircraft that is on the runway and has received a runway takeoff clearance advisory at the current instant, the Advisor designates the part of the runway starting at the aircraft's current position on the runway and forward (ahead/downstream) along the runway as blocked or, if the departure aircraft is approaching the runway, but not on the runway, the Advisor designates the part of the runway starting at the aircraft's assigned entry point to the runway and forward along the runway as blocked, as shown in Fig. 14. If the departure aircraft is on the runway but does not have a takeoff clearance, the Advisor only designates as blocked the segment of the runway covering the aircraft's current position on the runway or, if the aircraft is approaching the runway, the Advisor only designates its assigned runway entry point as blocked.

[0123] For an arrival aircraft that is occupying a runway (i.e., on or over the runway), the Advisor designates as blocked the part of the runway at and forward (ahead/downstream) of the aircraft's current position subject to any applicable clearance limit (e.g., hold short instruction), as shown in Fig. 15. Arrival aircraft runway blockages are assigned during the initial start-up assessment and include blockages due to arrival aircraft conducting missed approaches at the current instant. This initial blockage assignment also accounts for any missed approach that may be newly assigned by another component subsequently during the current assessment session.

[0124] For taxiing aircraft or other vehicles on a runway or approaching a runway with a runway taxi clearance advisory at the current instant, the Advisor designates as blocked the part of the runway starting at the vehicle's current position on the runway and forward along the portion of the runway about to be traversed by the taxiing aircraft or other vehicle (i.e. along the taxiing aircraft or other vehicle's path along or across the runway) or, if the aircraft or other vehicle is approaching the runway, the Advisor designates as blocked the part of the runway starting at the vehicle's assigned entry point to the runway and forward along the portion of the runway about to be traversed by the taxiing aircraft or other vehicle, as shown in Fig. 16.

[0125] For non-nominal operations, the Advisor blocks the entire runway or runways used by or affected by the aircraft or other vehicle at the current instant, as shown in Fig. 17.

[0126] Issue Initiate Missed Approach Instruction Advisory ~ This component examines the next pending arrival aircraft aligned for landing at each runway, and determines whether the aircraft is crossing or has crossed the missed approach decision point at the current instant and whether any portion of the landing runway is blocked at the current instant, as shown in Fig 18. If these conditions exist, the Advisor determines whether any special rules (e.g., landing and hold short, multiple runway occupants due to special daylight/new technology procedures) apply that would allow the aircraft to land on an occupied or partially blocked runway (e.g., a continuous entry region of the runway is unblocked for a length at least equal to the allowed spacing). If special rules do not apply, the Advisor generates and issues a new initiate missed approach instruction advisory to the runway traffic controller. If special rules apply that allow landing on an occupied or partially blocked runway, a missed approach advisory is not issued by the Advisor, as shown in Fig 18.

[0127] Issue Preemptive Runway Taxi Clearance Advisory— This component generates runway taxi crossing clearance advisories that preempt (i.e., have interraptive precedence over) takeoff clearances on current departures-only runways. This is the reason that this component precedes the issue of takeoff clearance advisories component in the methodology shown in Fig. 6. The issue preemptive runway taxi crossing clearance advisories component determines the need for preemptive runway taxi crossing clearance advisories for taxiing aircraft and other vehicles that are pending entries to a runway (i.e., first in line at a runway entry point) or are queued behind a pending entry, as shown in Fig. 19. Each runway may have multiple taxi entry points. If the Advisor determines that there is a need for preemptive runway taxi crossing clearance advisories, the Advisor issues preemptive runway taxi crossing clearance advisories to the runway controller for one or more aircraft or other vehicles that are pending entries or queued behind pending entries to taxi across a runway.

[0128] For each runway, the Advisor determines if preemptive taxi crossings are allowed for this runway. If preemptive taxi crossings are allowed, the Advisor determines if a taxi queue of at least one aircraft or other vehicle exists for at least one runway taxi crossing point that qualifies for preemption (e.g., the queue size exceeds a user-specified threshold), as shown in Fig. 20.

[0129] For runways qualifying for preemptive runway taxi crossing clearance advisories, the Advisor determines which pending aircraft or other vehicles to process next (e.g., the pending entry in the longest taxi crossing queue for this runway), as shown in Fig. 21. For this pending aircraft or other vehicle, the Advis'or determines whether the runway crossing is unblocked and whether the assigned/planned taxiway path for the aircraft or other vehicle beyond the runway is unblocked (i.e., an externally-derived surface taxi hold is not currently assigned to the aircraft/other vehicle). If these conditions exist, the Advisor issues a runway taxi clearance advisory for this aircraft or other vehicle to the runway traffic controller and updates the update runway system blockage state component. The Advisor proceeds to process each of the remaining aircraft or other vehicles queued behind this pending aircraft or other vehicle before processing the next pending aircraft or other vehicle at a different entry point for this runway.

[0130] For each subsequent queued taxiing aircraft or other vehicle in line to cross the runway, the Advisor generates a taxi clearance advisory for this vehicle to follow the preceding vehicle across the runway if this vehicle is eligible for a preemptive runway taxi crossing clearance advisory (e.g., this vehicle's place in queue is < the user-defined runway taxi crossing queue size threshold), the preceding vehicle is cleared to taxi across the runway, and this vehicle's

assigned/planned taxiway path beyond the runway is unblocked (i.e., an externally- derived surface taxi hold is not currently assigned to the vehicle), as shown in Fig. 22. The Advisor issues a preemptive runway taxi crossing clearance advisory to the runway traffic controller and updates the update runway system blockage state component.

[0131] Issue Takeoff Clearance Advisories - This component determines the eligibility of aircraft for takeoff, generates and issues takeoff clearance advisories for departure aircraft that are pending takeoffs, and issues takeoff clearance advisories to runway controllers, as shown in Fig. 23. Pending takeoffs are those departure aircraft that are first in a line at a runway entry point (which includes aircraft on taxi approaches to a runway and aircraft in position on a runway), that are waiting for takeoff clearance. Each runway may have multiple entry points for takeoff and each entry point may have multiple feeder lines for queued departure aircraft.

[0132] For each departure runway and each pending takeoff aircraft, the Advisor designates a pending takeoff aircraft (i.e., aircraft first in its queue) as eligible for takeoff if this aircraft's takeoff at the current instant satisfies all externally-derived traffic restrictions (e.g., the takeoff time fits into any time-window constraint), the part of the takeoff runway to be traversed is unblocked, and all minimum spacing requirements with predecessor and successor arrival and departure aircraft on all runways are satisfied, as shown in Fig. 24.

[0133] From among the departure aircraft eligible for takeoff, the Advisor selects one aircraft for immediate takeoff clearance advisory assignment, as shown in Fig. 25. The method for selecting this initially preferred aircraft for immediate takeoff clearance advisory assignment is subject to user selectable options. The Advisor provides a default procedure by which the eligible aircraft having the earliest requested takeoff time is selected. Alternative options, such as flight type (e.g., commercial or general), or operating capability (e.g., required navigation

performance level, data link equipage) or aircraft type (e.g., commercial aircraft, military aircraft or general aviation aircraft) may be used for selecting this initially preferred aircraft for immediate takeoff clearance advisory assignment. The Advisor issues this takeoff clearance advisory to runway traffic controllers and updates the update runway system blockage state component.

[0134] The resulting updated runway system blockage state, as well as the approved takeoff time and runway (both based on the newly issued advisory) serve to constrain subsequent takeoff clearance advisories in the following manner. From among the remaining departure aircraft eligible for takeoff, the Advisor selects another aircraft for takeoff clearance advisory evaluation. The selection process is the same as used for the initially preferred aircraft. For this eligible takeoff aircraft, the Advisor generates a runway takeoff clearance advisory if this aircraft's takeoff at the current instant is such that the takeoff runway to be traversed is unblocked and all minimum spacing requirements with predecessor and successor arrival and departure aircraft on all runways are satisfied. The Advisor issues this clearance advisory to traffic controllers and updates the update runway system blockage state component. This process is repeated until eligible takeoffs from all departure runways are evaluated, subject to the constraint that only one takeoff clearance advisory may be assigned to a runway at the current instant.

[0135] Issue Runway Taxi Clearance Advisory— This component generates and issues runway taxi clearance advisories for taxiing aircraft and other vehicles that are pending entries to a runway (first in line at a runway entry point) that are ready to taxi across a runway or along a runway. The order for selecting vehicles for taxi clearance advisory issuance is subject to user-definition, but the Advisor provides a default procedure by which taxi crossings are processed before taxiing along runways, as shown in Fig. 26. Each runway may have multiple taxi entry points.

[0136] From among the taxiing aircraft and other vehicles waiting for runway crossing clearance, the Advisor selects one of these vehicles for runway taxi clearance advisory evaluation, as shown in Fig. 27. The method for selecting this initially preferred aircraft or other vehicle is subject to user-defined options. The Advisor provides a default procedure by which the eligible aircraft or other vehicle having the earliest requested runway taxi entry time is selected. For the selected pending runway taxi crossing aircraft or other vehicle, the Advisor generates a runway taxi crossing clearance advisory if the taxi crossing movement of the aircraft or other vehicle at the current instant is such that the runway segment to be traversed is unblocked, minimum spacing requirements with inbound arrival aircraft to this runway are satisfied, and the aircraft or other vehicle's

assigned/planned taxiway path beyond the runway is unblocked (i.e., an externally- derived surface taxi hold is not currently assigned to the aircraft or other vehicle).

The Advisor issues the runway taxi clearance advisory to traffic controllers for this aircraft or other vehicle and updates the update runway system blockage state component. The resulting updated runway system blockage state as well as the approved runway crossing time (both based on the newly issued advisory) are factored into subsequent runway taxi clearance advisories. This process is repeated until all pending runway taxi crossing aircraft and other vehicles are evaluated.

[0137] The process for generating clearance advisories for aircraft and other vehicles to taxi along runways, as shown in Fig. 28, is similar to that described in the preceding paragraph for runway taxi crossing advisories, but has a slightly different set of criteria for approving a taxi clearance advisories. For pending taxiing along runways, the Advisor generates a runway taxi clearance advisory if taxiing along this runway is allowed (e.g., the runway is not used by arrivals) and the vehicles' taxi movement at the current instant is such that the runway segment to be traversed is unblocked and the vehicle's assigned/planned taxiway path beyond the runway is unblocked (i.e., an externally-derived surface taxi hold is not currently assigned to the vehicle). The Advisor issues the runway taxi clearance advisory to traffic controllers for this aircraft and updates the update runway system blockage state component. The resulting updated runway system blockage state as well as the approved runway taxi time (both based on the newly issued advisory) are factored into subsequent runway taxi clearance advisories. This process is repeated until all pending runway taxi crossing aircraft and other vehicles are evaluated.

Real-Time Computer Simulation Embodiment

[0138] In this embodiment, the Advisor is a module within a real-time simulation system. The simulation system is comprised of hardware/software modules that interface with human traffic controller laboratory test subjects. In this embodiment, the advisories generated by the Advisor are provided to the traffic controller test subjects through the interface, as shown in Fig. 11. The Advisor generates hold advisories by applying the same solution process described above for the automated airport traffic control system embodiment.

Fast-Time Computer Simulation Embodiment

[0139] In this embodiment, the Advisor is a module within a fast-time simulation system. Here the simulation system is comprised of hardware/software modules, including a module that models traffic control operations, as shown in Fig. 11. Advisories generated by the Advisor are provided to the traffic controller module within the structure of the fast time simulation system. In this embodiment, the Advisor generates hold advisories by applying the same solution process described above for the automated airport traffic control system embodiment.

[0140] While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.

Claims

What is claimed:

1. A method for providing clearances for managing vehicle movement on a runway at an airport, the method comprising:

receiving airport infrastructure information comprising status of airport runways, taxiways, airspace fixes and route procedures, operating parameters and traffic restrictions;

determining a current position for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport at a predetermined time interval;

receiving an assigned path for each aircraft and other vehicle moving on an airport surface;

receiving traffic control advisories and instructions issued by traffic controllers;

updating the runway system blockage status;

generating an initiate missed approach instruction advisory for a pending landing aircraft if runway blockage is present on the runway when the pending landing aircraft is crossing or has crossed a user-defmed missed approach point at the current instant;

communicating to a traffic controller the initiate missed approach advisory that includes instructions for the pending landing aircraft to abort landing on the runway;

generating a preemptive runway taxi crossing clearance advisory for taxiing aircraft or other vehicles in a queue when a number of taxiing aircraft or other vehicles in the queue exceeds a user-defined limit;

communicating to the traffic controller the preemptive runway taxi crossing clearance advisory that includes instructions for one or more aircraft or other vehicles to proceed across a segment of a runway;

generating a runway takeoff clearance advisory for a pending departure aircraft that is either next in line to enter the runway for takeoff, or is currently positioned on the runway ready to takeoff when no part of the runway to be traversed is blocked at or forward of the current position of the pending takeoff aircraft;

communicating to the traffic controller the runway takeoff clearance that includes instructions for the pending departure aircraft to proceed to takeoff on the runway;

generating a runway taxi crossing clearance advisory for a pending taxiing aircraft or other vehicle that is next in line to enter the runway and taxi across or along the runway when no part of the runway to be traversed is blocked at or forward of the current position of the pending taxi aircraft or other vehicle; and communicating to the traffic controller the runway taxi crossing clearance advisory that includes instructions to proceed across or along a segment of a runway.

2. The method in claim 1, wherein generating the runway takeoff clearance advisory for the pending takeoff aircraft comprises determining the eligibility of each pending aircraft for takeoff from each runway and selecting one eligible aircraft for each runway for runway takeoff clearance advisory generation.

3. The method of claim 2, wherein determining the eligibility of a pending aircraft for takeoff from each runway comprises determining whether aircraft minimum spacing requirements, runway blockage constraints and traffic restrictions are satisfied for the pending aircraft for takeoff.

4. The method of claim 3, wherein determining aircraft minimum spacing requirements are satisfied for the runway takeoff clearance advisory comprises: comparing a current position of each pending takeoff aircraft on each runway with a current position of predecessor aircraft and a current position of successor aircraft on the same runway and different runways; and

determining that time spacing and distance spacing between the current position of the pending takeoff aircraft and the current position of predecessor aircraft and successor aircraft exceeds aircraft minimum spacing requirements.

5. The method of claim 4, wherein comparing aircraft time spacing and distance spacing between aircraft on different runways includes runways on a single airport and runways on different airports.

6. The method of claim 3, wherein determining runway blockage constraints comprises determining that no part of the runway to be traversed at or forward of the current position of the pending takeoff aircraft is blocked.

7. The method of claim 3, wherein determining whether traffic restrictions for a runway takeoff clearance are satisfied comprises determining that the pending aircraft taking off at the current instant complies with at least one of a takeoff time window and an earliest takeoff time.

8. The method of claim 1, wherein generating the initiate missed approach instruction advisory comprises determining that the landing runway is not blocked at or forward of the threshold or that insufficient space is available on the runway to accommodate landing where rules allow partial blockage/multiple runway occupancy.

9. The method of claim 1, wherein generating a runway taxi clearance advisory comprises determining whether aircraft minimum spacing requirements and runway blockage constraints are satisfied for a pending runway taxi crossing aircraft or other vehicle.

10. The method of claim 9, wherein determining minimum spacing requirements for a pending runway taxi crossing aircraft or other vehicle are satisfied comprises: comparing a current position of a pending runway taxi crossing aircraft or other vehicle for the runway with a current position of successor landing aircraft on the same runway and crossing runways; and

determining that time spacing and distance spacing between the current position of the pending runway taxi crossing aircraft or other vehicle and the current position of successor landing aircraft exceeds aircraft minimum spacing requirements.

11. The method of claim 9, wherein determining runway blockage constraints for a pending runway taxi crossing aircraft or other vehicle are satisfied comprises determining that no part of the runway and runway-exit taxiways to be traversed are blocked at or forward of the current position of the pending taxi aircraft or other vehicle.

12. The method of claim 1, wherein generating a runway taxi clearance advisory for a pending runway taxi aircraft or other vehicle along a segment of runway on a current non-arrival runway comprises determining that runway blockage constraints are satisfied for the pending runway taxi aircraft or other vehicle along the segment of runway on the non-arrival runway.

13. The method of claim 12, wherein determining runway blockage constraints are satisfied for taxiing on the segment of runway on the non-arrival runway comprises determining that the runway segment is not being used by landing aircraft and that no part of the assigned runway and runway-exit taxiways to be traversed is blocked at or forward of the current position of the pending taxi aircraft or other vehicle.

14. The method of claim 1, wherein generating preemptive runway taxi crossing clearances further comprises determining that runway blockage constraints are satisfied for the first pending taxi aircraft or other vehicle in the queue and at least one subsequent pending taxi aircraft or other vehicle in the queue.

15. The method of claim 14, wherein determining whether runway blockage constraints for the first pending taxi aircraft or other vehicle in the queue comprises determining that no part of the assigned runway and runway-exit taxiway to be traversed is blocked at or forward of the current position of the first pending taxi aircraft or other vehicle.

16. The method of claim 15, wherein satisfying runway blockage constraints for a subsequent queued taxi aircraft or other vehicle comprises determining that the taxi crossing clearance advisory has been generated for the first pending taxi aircraft or other vehicle in the queue and no part of the assigned runway-exit taxiways to be traversed is blocked at or forward of the current position of the at least one subsequent pending taxi aircraft or other vehicle.

17. The method of claim 4 wherein aircraft minimum spacing requirements are dependent on the level of visual meteorological conditions (VMC) or instrument meteorological conditions (IMC) that are in effect.

18. A method for providing clearances for managing vehicle movement on a runway at an airport, the method comprising:

receiving airport infrastructure information comprising status of airport runways, taxiways, airspace fixes and route procedures, operating parameters and traffic restrictions;

receiving an assigned path for each aircraft and other vehicle moving on an airport surface;

determining a current position for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport, wherein current position and assigned path for each aircraft and other vehicle moving on an airport surface and in airspace proximate to the airport is determined in response to frequently occurring events;

receiving traffic control advisories and instructions issued by traffic controllers;

updating a runway system blockage status;

generating an initiate missed approach instruction advisory for a pending landing aircraft if runway blockage is present on the runway when the pending landing aircraft is crossing or has crossed a user-defmed missed approach point at the current instant; communicating to a traffic controller the initiate missed approach advisory that includes instructions for the pending landing aircraft to abort landing on the runway; generating a preemptive runway taxi crossing clearance advisory for taxiing aircraft or other vehicles in a queue when a number of taxiing aircraft or other vehicles in the queue exceeds a user-defined limit;

communicating to the traffic controller the preemptive runway taxi crossing clearance advisory that includes instructions for one or more aircraft or other vehicles to proceed across or along a segment of a runway;

generating a runway takeoff clearance advisory for a pending departure aircraft that is either next in line to enter the runway for takeoff, or is currently positioned on the runway ready to takeoff when no part of the runway to be traversed is blocked at or forward of the current position of the pending takeoff aircraft; and

communicating to the traffic controller the runway takeoff clearance that includes instructions for the pending departure aircraft to proceed to takeoff on the runway.

19. The method of claim 18, wherein the frequently occurring events comprise at least one of a requested runway entry event, a runway exit event, a taxiway intersection crossing event, a runway intersection crossing event, an airspace fix crossing event, and invocation by an external function event.