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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

QUARTER 4: JUL–SEP 2011

Airspace Systems 

Program Newsletter

National Aeronautics and Space Administration

www.nasa.gov

p2 (TAPSS) Terminal Area 

Precision Scheduling System

p7 Field Demonstration of New 

Departure Release Technology
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

(TAPSS) Terminal Area Precision 

Scheduling System

Air traffic controllers currently rely on simple decision 

support tools to safely separate and maintain an orderly 

flow of aircraft within the National Airspace System 

(NAS). As the volume of air traffic grows, greatly 

enhanced tools will be needed to maintain and increase 

system performance. 

To help controllers keep up with the anticipated 

heavy workload, NASA is developing several advanced 

automation tools that will provide controllers with 

more accurate predictions about the nation’s air traffic flow, weather, and routing. The greater precision in 

this information will enable a next-generation air traffic 

management system (referred to as NextGen), which 

will be safer, greener, and more efficient. These new 

tools require increased information sharing and coordination among air traffic controllers and pilots within 

the future NextGen. A critical goal in NASA’s air traffic 

management research and development process is ensuring that these tools work well together.

The Terminal Area Precision Scheduling System 

(TAPSS) research at NASA Ames Research Center tests 

the integration of many of NASA’s technologies that 

aim to improve operations in the airspace immediately 

surrounding the airport, known as the terminal area.

These technologies include: 

•	 Precision scheduling enhancements to the previously deployed Traffic Management Advisor (TMA), 

which creates time-based metering arrival schedules 

for terminal-merge points

// Technical/Programmatic Highlights 

NASA researchers participate as air traffic controllers during Terminal Area Precision Scheduling System (TAPSS) 

shakedown simulations in NASA’s Air Traffic Management Laboratory. Photo credit: NASA/Dominic Hart
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

•	 Required Navigation Performance/Area Navigation

(RNP/RNAV), which enables aircraft to fly more

fuel efficient routes from cruise altitude to landing

•	 Controller Managed Spacing (CMS) tools, which

provide speed advisories for metering in the 

terminal airspace

•	 Efficient Descent Advisor (EDA), which enables

aircraft to use minimum fuel consumption descents 

while being metered in busy terminal areas, thereby 

minimizing environmental emissions

TAPSS research uses human-in-the-loop simulations 

to evaluate the performance of the NextGen tools in 

congested airspace where there is a significant need for 

high-precision automation aids, such as the Southern 

California Terminal Radar Approach Control (TRACON) Metroplex, an airspace environment comprising 

multiple large, interdependent airports. Several traffic 

scenarios with varying levels of complexity are studied 

using models of traffic into Los Angeles International 

Airport, a high-flow airport. 

The concept of precision metering with staged delay 

distribution is evaluated to account for uncertainty 

within the airspace system. Traditionally, most arrival 

delay is absorbed near the airport where controllers and 

pilots use vectoring, or circling, to accommodate delay, 

which increases congestion in the terminal area. By 

applying simple variations in speed from cruise altitude 

to landing, instead of vectoring in the terminal area, 

small amounts of delay are distributed over the length 

of a flight, relieving some of the congestion that builds 

up near the airport. This leads to a much more efficient 

NASA researchers evaluate the performance of NextGen air traffic management technologies during TAPSS simulations. 

Photo credit: NASA/Dominic Hart
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

flow into busy terminal areas, less fuel burn, and reduced workload for pilots and controllers. Both nominal and off-nominal conditions are tested to understand 

the robustness of the automation under anticipated air 

traffic growth projections for NextGen. 

The first two TAPSS simulations modeled three Air 

Route Traffic Control Center (or simply, “Center”) 

arrival-metering sectors and five TRACON (three 

feeder and two final) sectors with controller positions 

interacting with workstation-based pilot/aircraft simulation positions. The current air traffic control paradigm of voice and radio-based arrival clearances is used, 

allowing for near-term implementation into the NAS. 

Simulation participants, who often include experienced 

air traffic controllers and pilots, provide feedback on 

performance, workload, and acceptability in order to 

improve the functionality of the automation. Data

on delay and controllability of the traffic along RNP/

RNAV routes is collected during each simulation and

the results are compared against current-day operations. The data collected may also provide insights into 

changes in airspace volume and fuel savings.

The third high-fidelity human-in-the-loop simulation 

will assess the feasibility, performance and potential 

benefits for near-term application in the NAS over a 

two week period in November and December. Major

questions to be answered by the HITL are:

•	 Is the system robust enough to include airport routing infrastructure with a limited set of Area Navigation (RNAV)/Required Navigation Performance

(RNP) procedures, and can those RNAV/RNP

NASA researchers test pilot aircraft simulation workstations during TAPSS shakedown simulations in NASA’s 

Air Traffic Management Laboratory. Photo credit: 

NASA/Dominic Hart

NASA researchers participate as air traffic controllers 

during TAPSS shakedown simulations in NASA’s 

Air Traffic Management Laboratory Photo credit: 

NASA/Dominic Hart
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

procedures co-exist with the more common 

arrival procedures?

•	 For very-high density operations, are the advanced

controller display enhancements necessary to 

gain the full advantage of the TAPSS capability 

to increase airport throughput by 10% while also 

increase efficient descents by 50%? 

Teams from Raytheon and General Electric Aviation

also have visited the simulation to evaluate implications 

for implementation in the Federal Aviation Administration’s (FAA’s) Standard Terminal Automation Replacement System (STARS) as well as impact to the avionics 

community. Ames additionally hosted representatives of 

the reorganized FAA’s Advanced Technology Development and Prototyping Group that may consider this 

technology to meet some of the FAA’s NextGen implementation goals. 

Another goal of the TAPSS research is to further 

develop air traffic management simulation capabilities 

and to validate the infrastructure for studying integrated NextGen tools in complex human-in-the-loop 

simulations. In the future, TAPSS will explore the issues of arrival schedule non-conformance and recovery 

from the air traffic controller’s perspective to provide 

insight into the development of automated schedule 

recovery tools. 

(POCs: Harry Swenson, Jane Thipphavong)

AIAA’s 3rd Atmospheric and Space 

Environments Conference,

June 27-30, 2011

Drs. Fred Proctor and Nash’at Ahmad represented

the Airspace Systems Program (ASP) at the conference. Both Drs. Ahmad and Proctor co-chaired

and presented papers in the session on “Lidar Wake 

Applications, Database Management and Atmospheric

Simulation.” Additionally, Dr. Proctor co-chaired a

presented in the session on “Wake Vortex Modeling

and Analysis.” In the first session, Dr. Ahmad presented

five case studies of LES simulation of convective storms

and their association with convection induced turbulence. The convective events modeled in the five simulations ranged from large mesoscale convective systems 

to isolated tropical maritime convection. The validation 

of model results with radar data and other observations 

was reported and an aircraft-centric turbulence hazard metric calculated for each case was discussed. The 

TAPSS Development Team. In this photo (l to r): Hai 

Ou-Yang, Anthony Seo, Daniel Du, Leonard Bagasol, Paul 

Lin, Jane Thipphavong, Chris Sullivan, Harry Swenson, 

Liang Chen, Danny Chiu, Arjun Ravishankar, Alex 

Sadovsky. Photo credit: NASA/Dominic Hart
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

turbulence analysis showed that large pockets of significant turbulence hazard can be found in regions of weak 

radar reflectivity. Moderate and severe turbulence was 

often found in building cumulus turrets and overshooting tops. In the second session, Dr. Proctor presented

results from large eddy simulations (LES) that explored

the influence of crosswind shear on aircraft wake vortices. The LES parametric studies confirmed that the

vertical gradient of crosswind shear can influence vortex 

trajectories and rate of circulation decay. The effect of 

shear may cause the vortices to tilt and separate. Also, 

the vortex linking time may either decrease or increase 

depending upon the sign of both the first and second 

vertical derivates of the environmental crosswind. 

Several papers were also presented that described the 

work sponsored under the ASP’s NextGen-Concepts 

and Technology Development (CTD) project’s NASA

Research Announcement, “Enabling Super-Dense

Operations by Advancing the State of the Art of FastTime Wake Vortex Modeling.” The papers discuss

the development and accuracy of fast-time wake prediction models, and assessed the accuracy of pulsed Lidar 

in tracking and estimating the circulation strength of 

aircraft wake vortices. All papers are listed below. 

(POC: Fred Proctor)

1.	F. Proctor and N. Ahmad, “Crosswind

Shear Gradient Affect on Wake Vortices,”

AIAA-2011-3038. 

2.	N. Ahmad and F. Proctor, “Large Eddy Simulations

of Severe Convection Induced Turbulence,” 

AIAA-2011-3201. 

3. M. Pruis (Northwest Research Associates) and 

D. Delisi (Northwest Research Associates),

“Assessment of Fast-Time Wake Vortex Prediction

Models using Pulsed and Continuous Wave Lidar 

Observations at Several Different Airports,”

AIAA-2011-3035. 

4. M. Pruis (Northwest Research Associates) and 

D. Delisi (Northwest Research Associates),

“Comparison of Ensemble Predictions of a New

Probabilistic Fast-Time Wake Vortex Model and

Lidar Observed Vortex Circulation Intensities and

Trajectories,” AIAA-2011-3036. 

5. M. Pruis (Northwest Research Associates) and 

D. Delisi (Northwest Research Associates),

“Correlation of the Temporal Variability in the

Crosswind and the Observation Lifetime of Vortices

Measured with a Pulsed Lidar,” AIAA-2011-3199. 

6.	D. Lai (Northwest Research Associates), D. Jacob

(Lockheed Martin Coherent Technologies), F. Lo

(Northwest Research Associates) and D. Delisi

(Northwest Research Associates), “Assessment 

of Pulsed Lidar Measurements of Aircraft Wakes 

Using a Lidar Simulator: Vortex Position Estimates

for IGE, Linking, and Oblique Viewing, and

Dependence of Vortex Lifetime on SNR,”

AIAA-2011-3197. 

7.	D. Jacob (Lockheed Martin Coherent Technologies)

et al., “Assessment of Lockheed Martin’s Aircraft 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

Wake Vortex Circulation Estimation Algorithms

Using Simulated Lidar Data,” AIAA-2011-3196.

8.	D. Ramsey (Aerospace Innovations) and D. Nguyen

(Aerospace Innovations), “Characterizing Aircraft 

Wake Vortices with Ground-Based Pulsed Coherent

Lidar: Effects of Vortex Circulation Strength

and Lidar Signal-to-Noise Ratio on the Spectral 

Signature,” AIAA-2011-3198.

Successful FBTM Technology Transfer, 

July 14, 2011

In a model of effective collaboration, an FAA-NASA

Research Transition Team successfully refined the 

Flow Based Trajectory Management (FBTM) concept.

FAA, NASA and JPDO executives met to complete

the official close out and declare success on FBTM, a

NextGen technology transfer initiative between the 

FAA and NASA.

FBTM modifies aircraft trajectories in flight to

reduce airspace complexity and increase capacity. It is a 

major NextGen component and part of a larger plan to 

integrate and facilitate seamless trajectory management 

among the major National Airspace System automation functions. FBTM researchers conducted two

major human-in-the-loop simulations, each of which 

simulated operations at FAA en route centers with

participation by air traffic controllers, traffic managers, and supervisors. Results showed that the FBTM

concept is not only feasible, but beneficial in supporting NextGen initiatives toward “best-equipped, bestserved” operations. 

(POC: Kevin Hatton, AJP-66)

Field Demonstration of New Departure 

Release Technology, July 2011

ASP researchers in collaboration with the FAA,

American Airlines, and Dallas/Fort Worth (DFW)

airport have completed a multi-week field evaluation 

of the Precision Departure Release Capability (PDRC).

PDRC uses trajectory-based takeoff time estimates

NASA develops PDRC by integrating a representative 

surface traffic management system (base of the yellow 

arrow) with an arrival/departure management system 

(head of the yellow arrow). 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

from a surface automation system to improve en route 

tactical departure scheduling into constrained overhead 

flows. This initial field evaluation began on July 13th

and ended on July 29th. PDRC user interfaces and

NASA observers were stationed at four locations: the 

Fort Worth Air Route Traffic Control Center’s Traffic

Management Unit, the DFW East air traffic control

tower, American Airlines’ DFW ramp tower, and

NASA’s North Texas research station. The first week 

was devoted to system shakedown and controller training. During the second week, the system was used in a

shadow mode that evaluated PDRC advisories without

affecting actual operations. The 12-day test period 

concluded with several operational evaluations where 

controllers successfully used PDRC advisories to schedule actual DFW departures. Anecdotal feedback from

these initial evaluations indicated that PDRC takeoff

time estimates and en route departure schedules were 

usable, and that PRDC shows promise of providing

the expected benefits. Detailed results are forthcoming.

NASA’s PDRC research activity is on track for technology transfer to the FAA in June 2012.

(POC: Shawn Engelland)

T-TSAFE Vertical Resolutions Tested,

July/August 2011

Controllers evaluated the vertical resolutions and 

expanded controller interface for Terminal Tactical 

Separation Assured Flight Environment (T-TSAFE) in

July and conducted pseudo pilot training in August to

prepare for the upcoming evaluation of the conflict 

detection and resolution tool. The T-TSAFE concept

takes TSAFE, as developed for use in en route airspace,

and adapts it for use in terminal airspace. Terminal airspace is crowded and has more complicated separation 

criteria than high altitude airspace, and current tools 

flag too many false conflicts, which lowers controller 

trust in the automation and decreases its usefulness. 

T-TSAFE is designed to reduce false alerts in this complex airspace and provide controllers with suggested 

conflict resolutions. The current implementation of 

T-TSAFE now provides controllers with alerts for possible losses of separation and suggests conflict resolutions based on altitude changes. Suggested resolutions 

based on speed and heading changes will be added later 

this year. The focus of this evaluation was to validate 

the reasonableness of the T-TSAFE altitude resolutions

and to get controller feedback on the expanded interface. Data collection with retired controllers and pilots

occurred later in August. 

(POC: Savvy Verma)

Visit to the Washington ARTCC, 

August 2011

Jeremy Smith, Patricia Glaab, Jeff Viken, Nelson

Guerriero from NASA, and Ty Marien and members of Intelligent Automation, Inc. (IAI), visited the 

Washington Air Route Traffic Control Center to help 

inform the development, validation and benefits assessment of NextGen concepts currently being modeled in 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

systems-level simulations. This visit, arranged by IAI, 

allowed participants to talk directly with operations 

managers and to observe controllers in the process of 

handling air traffic. Tony Manzione of the FAA hosted

the visit, which spanned the late morning to early afternoon time frame. The professionalism and capabilities 

of the controllers were continuously demonstrated as 

they managed routing around storms in the northeast 

and responded to varying arrival and departure rates 

caused by changing weather conditions. Each participant was allowed to sit with a sector controller to 

observe and listen as they worked. The Washington 

Center management appeared to be very receptive to 

new technologies and tools to facilitate their operations. They are very close to deploying the En-Route

Automation Modernization system, which will replace 

the current en-route host computer and add significant 

situational awareness and user configurability improvements. The departure flow manager demonstrated use 

of the Corridor Integrated Weather System, Departure

Spacing Program , and Traffic Situation Display that

are part of the current FAA tool suite. The arrival flow

manager demonstrated time-based arrival management and the shuffling of arrivals to accommodate 

traffic delayed either en-route or at the origin airport. 

Information gathered from this air traffic facility 

visit will be used by the Airspace Systems Program 

to advance the state of knowledge regarding air

traffic operations. 

(POC: Jeremy Smith)

Phase 3 SBIR Mid-Term Review, 

August 2011

Members of Intelligent Automation, Inc. (IAI) 

presented Airspace Systems Program (ASP) staff with 

a mid-term briefing and interim demonstration on the 

ASP Phase 3 SBIR for developing develop enhanced 

systems analysis and simulation capabilities to support 

exploration of NextGen operations concepts. When 

completed, the software will provide enhancements to 

software previously delivered to model Merging and 

Spacing (M&S) in the terminal airspace as well as new 

development of integrated weather effects and traffic 

flow management in the Airspace Concept Evaluation

System simulation. IAI is also conducting benefits 

assessment studies of the M&S concept using models 

for Newark’s Liberty, Atlanta’s Hartsfield-Jackson, and

the Dallas Fort Worth airports as part of this effort.

(POC: Jeremy Smith)

T-TSAFE Second Simulation, August 2011

After two weeks of data collection, the second Terminal Tactical Separation Assured Flight

Environment (T-TSAFE) experiment was completed

in late August. The experiment simulated the complex 

SoCal Terminal Radar Approach Control (TRACON) 

airspace surrounding the Los Angeles International 

airport because of the complexity of this airspace. 

The focus of the second T-TSAFE human-in-theloop experiment was to add altitude-based conflict 

resolutions for the controllers. The experiment added 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

refinements to the T-TSAFE controller interface. It also

tested T-TSAFE conflict alerts in the final approach all

the way to the threshold instead of using Automated 

Terminal Proximity Alert on the final approach and 

T-TSAFE in the rest of the TRACON. In addition to

digital data, the study assessed controller workload, 

situation awareness, trust, and obtained controller feedback on operational procedures. 

(POCs: Savvy Verma, Debbi Ballinger)

FAA Visits to Discuss NextGen Facilities 

and Technologies, August 2011

FAA representatives from the FAA Tech Center,

Cleveland Center, and the National Air Traffic 

Controllers Association (NATCA) visited NASA for 

a NextGen briefing to help inform their facilities 

modernization plan. NASA provided briefings on a 

wide range of topics that included project overviews 

and technical discussions on dynamic airspace configuration, traffic flow management, flexible airspace 

concepts, runway management, 3D path arrival management and near-term trajectory based operations. 

(POCs: Karl Bilimoria, Shon Grabbe, Yoon Jung)

Climb Trajectory Prediction Improves, 

August 2011

A new technique developed by NASA researchers has 

reduced climb-trajectory prediction errors by as much 

as 90% in laboratory testing. Aircraft climb trajectories are the most difficult to project. High errors in 

this regime increase the rate of false and missed alerts 

from separation assurance automation and reduce the 

A simulation of the Southern California TRACON airspace surrounding Los Angeles International Airport produced for the 

T-TSAFE study.
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

potential operational benefits of some advanced concepts for NextGen. In simulations with fuel weight 

uncertainty of up to 50% (or roughly 15% of gross 

weight), the algorithm is able to adapt to within 1% 

of gross weight within two minutes. As a result, the 

standard deviation of five-minute prediction altitude 

errors declined by 90%, from about 1000 ft to 100 ft. 

When uncertainties in climb speed and climb mach 

were modeled (at up to 10% each), the algorithm 

still improved climb prediction accuracy by 20-40% 

(roughly 300 to 600 feet). Based on these results, the 

adaptive climb-trajectory prediction algorithm is 

slated for integration into the trajectory predictor of 

the Center/TRACON Automation System, NASA’s

real-time ground-based prototype system. 

(POCs: David Thipphavong, Charles Schultz)

Simulation Shows Viability of Efficient New 

Weather-Avoidance Routing Capability, 

September 2011

The “Trajectory-Based Automation System for En

Route and Transition Airspace” (TBAS-ET) project

successfully completed a two-week simulation evaluation with controllers and pilots in the loop. This 

Pilots on the flight deck of NASA’s Boeing 747-400 simulator during the TBAS-ET simulation. 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

TBAS-ET simulation studied a trajectory-based air traffic management operational concept that encompasses 

the use of datalink communication in a near-term, 

mixed-equipage environment. Initial results support 

the conclusion that significant operational efficiencies can be achieved by issuing complex yet efficient 

weather-avoidance routes via datalink communication. 

Furthermore, such operations appear to be viable even

in the near-term, before data communications are ubiquitous. In addition to investigating strategic and tactical 

weather avoidance, the simulation also evaluated new 

clearance procedures to improve controller/pilot communications, automated conflict resolution advisories, 

and improved tactical conflict detection using the 

ground-based TSAFE algorithm.

(POC: Chester Gong)

Meeting Kicks Off New DAC Research 

Effort, September 2011

A team of experienced air traffic management 

researchers from Metron Aviation, Intelligent 

Automation, Inc. (IAI), and the State University of 

New York at Stony Brook presented a research plan for 

Dynamic Airspace Configuration (DAC) in response to

uncertain weather. Severe weather makes regions of airspace unsuitable for air traffic, resulting in flight rerouting and delays. The adjusted flight patterns can be 

considerably different than the normal flight patterns, 

which current static airspace boundaries divide into 

regions of traffic that can be appropriately managed by 

a single team of air traffic controllers. This mismatch 

can lead to overworked air traffic controllers and potentially even more delayed and rerouted flights. The team 

presented methods for dynamically adjusting airspace 

boundaries that are robust to relevant uncertainties in 

order to better handle the unusual and uncertain flight 

patterns resulting from severe weather. Approaches for 

coordinating changes to flight patterns with airspace 

boundary changes were also presented. The team will 

evaluate their approaches with simulations conducted 

in the Airspace Concept Evaluation System.

(POC: Michael Bloem)

FAA Visits to Discuss Air Traffic 

Management Collaborations, 

September 2011

FAA traffic flow management leads from the Air

Traffic Control System Command Center, the Tech 

Center, and FAA Headquarters visited NASA to hear

presentations on its efforts to model the integrated 

impact of national- and local-level traffic management 

initiatives, the impact of aviation on the environment, 

methods for improving the flow of air traffic into 

Denver during the convective weather season, and the

Efficient Descent Advisor. Discussions also included

work on sector demand estimation, modeling the 

integrated impact of pre-departure reroutes and 

ground holding, and development of a tool to acquire, 

evaluate, and develop data mining techniques using 

digitized traffic management initiatives. Lastly, a 
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Airspace Systems Program Newsletter: Quarter 4, JUL–SEPT 2011

demonstration of the dynamic weather routing tool 

was provided. Follow-on discussions included an invitation by the FAA to participate in a detailed research

gap analysis activity in November to identify areas of 

mutual interest. 

(POC: Shon Grabbe)

NASA Surface Researchers Meet with US 

Airways, September 2011

Yoon Jung, Gautam Gupta, and Waqar Malik visited Charlotte (CLT) and Philadelphia (PHL) airports 

to discuss partnering opportunities with US Airways 

executives and staff including the vice president of 

CLT operations, Terri Pope, and the director of air 

traffic control and flight operations, Bill Murphy. The 

US Airways management team has a strong desire to 

improve CLT operations by adopting new technologies 

that would help to more efficiently manage ramp operations through improved coordination with air traffic 

control counterparts including the air traffic control 

tower. They also have a strong motivation to collaborate with the airport authority, the FAA and the local

community in order to reduce environmental impacts. 

CLT is the second largest airport in the east coast after 

Atlanta in terms of traffic volume and almost 90% of 

aircraft operations are from US Airways. Many of the 

flights are regional jet traffic. Airport surface traffic at 

CLT is experiencing significant departure delays due 

to lack of coordination between en route/terminal

and surface, often resulting in 15-20 aircraft sitting 

in the departure queue wasting fuel and generating 

carbon emissions. A few specific collaboration ideas for 

NASA/US Airways were discussed, including environmental analysis and modeling as well as adopting a 

time-based sequencing tool for air traffic control and 

airlines at CLT. 

(POC: Yoon Jung)
National Aeronautics and Space Administration

Headquarters

300 E. Street, SW

Washington, DC 20024

www.aeronautics.nasa.gov

www.nasa.gov