Kee Palopo

Interaction of Airspace Partitions and Traffic Flow Management Delay

The interaction of partitioning the airspace and delaying flights in the presence of convective weather is explored to study how re-partitioning the airspace can help reduce congestion and delay. Three approaches with varying complexities are employed to compute the ground delays. In the first approach, an airspace partition of 335 high-altitude sectors that is based on clear weather day traffic is used. Routes are then created to avoid regions of convective weather. With traffic flow management, this approach establishes the baseline with per-flight delay of 8.4 minutes. In the second approach, traffic flow management is used to select routes and assign departure delays such that only the airport capacity constraints are met. This results in 6.7 minutes of average departure delay. The airspace is then partitioned with a specified capacity. It is shown that airspace-capacity-induced delay can be reduced to zero at a cost of 20 percent more sectors for the examined scenario. While the first two approaches investigate the upper and lower bounds in terms of delay and number of sectors, the third approach investigates the tradeoff between the number of sectors and the delay by re-applying the traffic flow management using the re-partitioned sectors. In this approach, the weather constraints are reflected in the sector partitions, and the delay is shared between airspace and airports. The solutions discovered by this approach are 6.9 minutes of average delay with a 312 sector configuration and 8.1 minutes of delay with a 253 sector configuration. Results show that a sector design that is tailored to the traffic and weather pattern can reduce delay while reducing the number of sectors at the same time. However, airspace partitioning can only address the delays caused by airspace congestion. Even in the presence of convective weather, the airport capacity constraint causes the majority of the delay.

Economic and Safety Impacts of Flight Routing in the National Airspace System

ठA study analyzing the economic and safety impacts of different flight routing methods in the National Airspace System is presented. It compares filed flight routes, wind-optimal routes, and great-circle routes. Routing differences are measured by flight time, fuel burn, sector count, and number of conflicts. Wind-optimal routes exhibit on average approximately one percent less flight time and fuel burn than filed flight routes. In addition, they produce an average of 13 less conflicts in Class A airspace (18,000 feet and above). All three routing methods are qualitatively equivalent in terms of sector count distribution. These results agree with earlier studies, which investigated some combinations of these types of routes and metrics. The contribution of this paper is that it consistently compares the three routing methods across the United States using the four metrics.

Shadow Mode Assessment using Realistic Technologies for the National Airspace System (SMART NAS) Test Bed Development (Invited)

This paper is devoted to describing the development of a new NASA air traffic management simulation and testing system called the Shadow Mode Assessment using Realistic Technologies for the National Airspace System (SMART NAS) test bed. The test bed is a major activity of NASA’s air traffic management research portfolio and fills important gaps in the air traffic community’s simulation and testing needs for allowing more efficient acceleration and acceptance of NextGen and far-term concepts and technologies. The test bed will allow testing and validation in a realistic environment and provide rapid near-real-time “what-if” capability for air traffic management and airline decision support based on comprehensive real-time data feeds. The vision, requirements of the SMART NAS test bed and the effort for developing the test bed architecture are discussed. Finally, the five-year development plan is outlined.

Arrival Delay Absorption Using Extended Metering with Speed Control

§It is often the case that due to demand-capacity imbalance at an airport, flights are assigned by air traffic controllers an amount of delay that they must absorb before their expected arrival at the airport. This paper investigates the distance needed by aircraft to absorb such delays through a speed reduction of up to 10% with respect to their nominal speed. Thirty five representative days of operations with distinct traffic volume and delay characteristics are considered for the analysis. For each day, a simulation of traffic in the NAS is conducted in the absence of any constraints on sector or airport capacity thereby resulting in delay-free aircraft landing times. Flights are assigned delays due to demandcapacity imbalances at forty major US airports, which are computed through a first-comefirst-served scheduler. Distances from the airport where flights should reduce speed in order to absorb their assigned delay are computed through an aircraft trajectory generator. Analysis focuses on jet aircraft reaching their top-of-climb point at least 250 nautical miles from their destination airport. Out of all aircraft assigned delays, on average 73% were able to absorb that delay entirely through speed control. Of these aircraft, on average 93.5% of flights were able to absorb their assigned delay by reducing speed in either the same or an adjacent Air Route Traffic Control Center (ARTCC) from their arrival airport. ARTCCs that issue the highest number of advisories for speed reduction are Washington (ZDC), Atlanta (ZTL), and Chicago (ZAU). Finally, results are also provided for the specific cases of Las Vegas (LAS) and Phoenix (PHX) airports.

Benefit Assessment of the Precision Departure Release Capability Concept

A Precision Departure Release Capability concept is being evaluated by both the National Aeronautics and Space Administration and the Federal Aviation Administration as part of a larger goal of improving throughput, efficiency and capacity in integrated departure, arrival and surface operations. The concept is believed to have the potential of increasing flight efficiency and throughput by avoiding missing assigned slots and minimizing speed increase or path stretch to recover the slot. The main thrust of the paper is determining the impact of early and late departures from the departure runway when an aircraft has a slot assigned either at a meter fix or at the arrival airport. Results reported in the paper are for two scenarios. The first scenario considers flights out of Dallas/Fort Worth destined for Hartsfield-Jackson International Airport in Atlanta flying through the Meridian meter-fix in the Memphis Center with miles-in-trail constraints. The second scenario considers flights destined to George Bush Intercontinental/Houston Airport with specified airport arrival rate constraint. Results show that delay reduction can be achieved by allowing reasonable speed changes in scheduling. It was determined that the traffic volume between Dallas/Fort Worth and Atlanta via the Meridian fix is low and the departures times are spread enough that large departure schedule uncertainty can be tolerated. Flights can depart early or late within 90 minutes without accruing much more delay due to miles-in-trail constraint at the Meridian fix. In the Houston scenario, 808 arrivals from 174 airports were considered. Results show that delay experienced by the 16 Dallas/Fort Worth departures is higher if initial schedules of the remaining 792 flights are kept unaltered while they are rescheduled. Analysis shows that the probability of getting the initially assigned slot back after perturbation and rescheduling decreases with increasing standard deviation of the departure delay distributions. Results show that most Houston arrivals can be expected to be on time based on the assumed zero-mean Normal departure delay distributions achievable by Precision Departure Release Capability. In the current system, airport-departure delay, which is the sum of gate-departure delay and taxi-out delay, is observed at the airports. This delay acts as a bias, which can be reduced by Precision Departure Release Capability.

Interaction of airspace partitions and traffic flow management delay with weather

The interaction of partitioning the airspace and delaying flights in the presence of convective weather is explored to study how re-partitioning the airspace can help reduce congestion and delay. Three approaches with varying complexities are employed to compute the ground delays. In the first approach, an airspace partition of 335 high-altitude sectors that is based on clear weather day traffic is used. Routes are then created to avoid regions of convective weather. With traffic flow management, this approach establishes the baseline with per-flight delay of 8.4 minutes. In the second approach, traffic flow management is used to select routes and assign departure delays such that only the airport capacity constraints are met. This results in 6.7 minutes of average departure delay. The airspace is then partitioned with a specified capacity. It is shown that airspace-capacity-induced delay can be reduced to zero at a cost of 20 percent more sectors for the examined scenario. While the first two approaches investigate the upper and lower bounds in terms of delay and number of sectors, the third approach investigates the tradeoff between the number of sectors and the delay by re-applying the traffic flow management using the re-partitioned sectors. In this approach, the weather constraints are reflected in the sector partitions, and the delay is shared between airspace and airports. The solutions discovered by this approach are 6.9 minutes of average delay with a 312 sector configuration and 8.1 minutes of delay with a 253 sector configuration. Results show that a sector design that is tailored to the traffic and weather pattern can reduce delay while reducing the number of sectors at the same time. However, airspace partitioning can only address the delays caused by airspace congestion. Even in the presence of convective weather, the airport capacity constraint causes the majority of the delay.

Automated Scenario Generation for Human-in-the-Loop Simulations [STUB]

Automated Multi-Aircraft Control System scenario generation for Human-in-the-Loop evaluations of air traffic management concepts is described. The objective is to replace the difficult manual process with the automated process for creating an initial (seed) scenario that serves as a starting point for manual adjustments for creating the Human-in-the-Loop scenario. Methods for analyzing and comparing the seed-scenario generated using the automated process and the Human-in-the-Loop-scenario derived from it to meet the experiment objectives are discussed. Results of comparison of input Human-in-the-Loopscenario with the Multi-Aircraft Control System output are also presented. The main findings are: (1) many of the characteristics of the seed-scenario used for constructing the Human-in-the-Loop-scenario are preserved in the Human-in-the-Loop-scenario, (2) landing rate profile of the traffic generated by the Multi-Aircraft Control System using the input scenario compares reasonably well with that intended in the input scenario, and (3) many of the desired characteristics of the Human-in-the-Loop-scenario can be achieved by further automation.

Delay Sensitivity to Call For Release Scheduling Time

A goal of any precision departure concept, such as NASA Precision Departure Release Capability, is to improve throughput, efficiency and capacity by integrating departure, arrival and surface operations. This kind of concept is believed to have the potential of increasing flight efficiency and throughput by not missing assigned overhead-stream or arrival-stream slots. In the current Call For Release scheduling, a slot can be missed because of airport-departure delay, which is the sum of gate-departure delay, ramp delay, and taxi-out delay. This delay can be reduced by improved precision departure scheduling. The main thrust of the paper is to determine the delay-cost impact of Call For Release scheduling before gate-push-back and at gate-pushback. Seven different variations of scheduling algorithms were used in the simulation. Results reported in the paper considers 37,346 flights in the National Airspace System for one day in January 2011. Approximately 1,500 airports were included in the simulation. Results show that there is no significant benefit of scheduling before gate-push-back as opposed to at gate-push-back under assumed gate-departure and taxi-out time uncertainties, assuming a Call For Release is strategically done for all departures from all airports. However, if there were no gate-departure and taxi-out time uncertainty, which is unlikely in reality, the maximum benefit of scheduling an hour before gate-push-back is limited to 6.8% reduction in weighted delay (2*airborne delay + ground delay) compared to delay resulting from scheduling at gate-push-back.