Airspace Concept
Evaluation SystemState of Development
POC: Kee Palopo
Kee.Palopo@nasa.gov
10 December 2008
Outline
Process
 Requirements
 Development
ACES 6.0 (Near-term Capabilities)
Studies Using ACES
Planned ACES Development
2
Requirements Process
Project Driven (milestones and principal investigators)
Review
 Branch and Division
 Start with Research Question
 Experiment Plan
 Meetings
 Workshops and Conferences
Request For Proposals
3
Development Phases
Build N
Requirements*
Build N+1
One Year
FAA, Glenn, JPDO, Langley, Others
Main Build
*includes enhancement and maintenance
4
ACES 6.0
Communication, Navigation, and Surveillance (CNS)
models with uncertainty
Advanced Airspace Concept (AAC)
Pre-computed schedule of sector capacities
Dynamic Sub-sector Assignment
Swappable Trajectory Generator
Traffic Management Advisor
ACES-FACET
5
Studies Using ACES
S. Karahan, S. Zelinski, “Creating Convective Weather
Scenarios for Simulating Weather Reroutes,” AIAA
Modeling and Simulation Technologies Conference and
Exhibit,” AIAA 2007-6557 Hilton Head, South Carolina
Aug. 20-23, 2007
R. Windhorst, H. Erzberger, “Fast-Time Simulation of
an Automated Conflict Detection and Resolution
Concept,” 6th AIAA Aviation Technology, Integration and
Operations Conference (ATIO), Wichita, Kansas, Sept.
25-27, 2006
6
Studies Using ACES (cont’d)
S. Zelinski, L. Meyn, “Validating the Airspace Concept
Evaluation System for Different Weather Days,” AIAA
Modeling and Simulation Technologies Conference and
Exhibit, Keystone, Colorado, Aug. 21-24, 2006
K. Palopo, R. Windhorst, B. Musaffar, M. Refai,
“Economic and Safety Impacts of Flight Routing in the
National Airspace System,” 7th AIAA ATIO Conference,
Belfast, Northern Ireland, Sept. 18-20, 2007
7
Studies Using ACES (cont’d)
G. Chatterji, Y. Zheng, “Impact of Airport Capacity
Constraints on National Airspace System Delays,” 7th
AIAA ATIO Conference, Belfast, Northern Ireland, Sep.
18-20, 2007
S. Sahlman, “Description and Analysis of a High Fidelity
Airspace Model for the Airspace Concept Evaluation
System,” AIAA Modeling and Simulation Technologies
Conference and Exhibit, Hilton Head, South Carolina,
Aug. 20-23, 2007
8
Ongoing Studies Using ACES
Nation-wide Separation Assurance using AAC
 Single-center NAS-wide
 42K flights 24 hours
 25 hours on one high-end Mac
Wind-Optimal Study
 Annual basis
500
 1X traffic
300
 4 hours on 7 Linux machines
 Plot by airlines
400
200
100
0
1
3
5
7
9
11
13
15
17
19
9
Conflicts Types and Resolution Order
 Auto resolver is designed to resolve three
types of conflicts:
 Loss of separation conflicts
 Weather conflicts
 Arrival sequencing conflicts
 An aircraft may be involved with all three
types at the same time
Source: Dr. Heinz Erzberger
10
Conflicts Types and Resolution Order (cont’d)
 Auto resolver resolves conflicts in the following
sequence:
 Weather conflicts
 Arrival sequencing conflicts
 Loss of separation conflicts
11
Flow Chart for Algorithm
Input Conflict Pair
Resolution Maneuver Generator
Formulas and
logic for
calculating
simplified
resolution traj.
4D Trajectory Synthesizer
No
Heavy duty
numerical
calculations
Traj. completed?
Yes
Check traj. for conflicts
Yes
Conflicts detected ?
No
Res. Traj.
accepted
12
Resolution Process
Current list of conflicts
Pick next conflict
for resolution
Resolution algorithm
Continue this
loop until all
conflicts are
resolved
Yes
Updated at regular
intervals
Priority based on time to
first loss
Generates multiple resolutions
for each aircraft; special rules
for weather conflicts
Weather conflict?
No
Yes
Secondary conflict?
No
Update flight plan
Execute resolution
Current flight plan is replaced with
resolution flight plan
AAC Remarks
An algorithm that generates resolution
trajectories for the full spectrum of possible
conflicts has been designed
Simultaneously resolves conflicts with
convective weather, loss of separation conflicts
and sequencing conflicts.
Algorithm comprises a mix of rule-based
procedures and analytical formulas.
ACES has proven to be a valuable tool for
development and analysis of algorithm
14
AAC Remarks (cont’d)
Real time controller and pilot interactive
simulations have demonstrated high degree of
controller and pilot acceptance at up to 3x traffic
levels.
Web-based documentation of software has been
developed to assist in technology transfer to users
15
Another Separation Assurance Study
Trajectory prediction uncertainties for AAC:
 Aircraft weight
 Descent profile
 Wind uncertainty
 Maneuver initiation delays
Aircraft-based AAC
Multi-center AAC
Source: Dr. Todd Lauderdale
16
Trajectory Prediction Uncertainties
Predicted
Actual
Actual
Predicted
Can introduce uncertainties into the trajectory
used for conflict prediction
Uncertainties can be controlled and understood
17
Aircraft-Based AAC
r
Each aircraft is aware of all aircraft in the sensor range
‘r’
Each aircraft uses AAC to resolve conflicts of which
they are aware
18
Aircraft-based AAC Unresolved Conflicts
60
Unresolved Conflicts
50
40
30
20
10
0
0
10
20
30
40
50
60
70
80
90
Sensor Range (NM)
19
Aircraft-based AAC Time to First Loss
Time to First Loss (seconds)
650
600
550
500
450
400
350
300
0
10
20
30
40
50
60
70
80
90
Sensor Range (NM)
20
Aircraft-based AAC- Run Time
1400
Run Time (minutes)
1200
1000
800
600
400
200
0
0
10
20
30
40
50
60
70
80
90
Sensor Range (NM)
21
Multi-Center AAC
AAC can run in multiple
centers simultaneously
A buffer of control and
visibility can be
established around
each center
ZOB AAC
ZID AAC
ZDC AAC
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Planned ACES
Development
Integrate enhanced terminal model TME/STLE
into ACES 7-11
Port and Enhance Weather Agent
Enhance Traffic Flow Management (TFM)
Other Model Enhancements
Metric Enhancements (Dynamic Density,
Complexity, and AAC)
23
Planned ACES Development (cont’d)
Miscellaneous Supporting Tools
 Terminal Area and Airport Surface Editor
 ACES Viewer Development with Air Force Research
Laboratory
 ACES Toolbox Enhancements
24
STLE Surface Modeling
25
Automated Terminal Area
Node-link Generator
26
Example TAASE Editor View
27
Enhanced Terminal Modeling
Airport Air Traffic Control
 Model 4D Traffic Movement on Surface
 Determine runway takeoffs/landing and gate entries/exits
Airport TFM – Generate TFM Landing Restrictions
TRACON TFM – Propagate Arrival Fix Crossing
Restrictions
28
Enhanced Terminal Modeling (cont’d)
TRACON Air Traffic Control
 Model 4D Traffic Movement through Terminal Airspace
 Determine Airport Landing/Departure Fix Crossings
Flight – 4D Trajectory for Terminal/En Route Airspace
29
Airport Air Traffic Control
Surface 4D route/re-route planning with/without
Required Time of Arrivals
Surface 4D route/re-route and clearance limit
assignment
Surface domain representation: Gate, Ramp, Taxiway,
Runway
Gate assignment and occupancy management
Ramp and Taxiway intersection transit control with
gridlock resolution
30
Airport Air Traffic Control (cont’d)
Takeoff runway assignment
Runway takeoff/landing/taxi crossing transit control
Surface transit Required Time of Arrival conformance
monitoring/alerting
Surface traffic state monitoring/alerting
31
Airport Air Traffic Control (cont’d)
Autonomous flight movement with aircraft in-trail selfseparation
 Acceleration/Deceleration
 Nominal Roll/Stochastic speed assignment subject to speed
limit
32
Airport Traffic Flow Management
Gate assignment and occupancy time prediction
Runway assignment prediction
Surface 4D route prediction with/without Required Time
of Arrivals
Traffic Flow Management Runway takeoff/landing
planning
Takeoff-time Traffic Flow Management Restriction
generation
33
Airport ATC/TFM Utilities
Gate selector
Runway selector
Surface prescribed route assigner
Surface shortest path calculator
Air Traffic Control Runway takeoff/landing planner
34
TRACON Air Traffic Control
Terminal airspace 4D route/re-route planning
with/without Required Time of Arrivals
Terminal airspace 4D route/re-route and clearance limit
assignment
Landing runway assignment
Airspace fix transit control
Airspace transit Required Time of Arrivals conformance
monitoring/alerting
Airspace traffic state monitoring/alerting
35
TRACON Traffic Flow Management
Terminal airspace 4D route prediction with/without
Required Time of Arrivals
Arrival/Departure fix crossing planning
Airports operating conditions forecasting
Airports runway configuration planning
Arrival fix crossing-time Traffic Flow Management
Restriction propagation
36
MPAS Improvements
Make stable at aircraft minimum speed
Model short flights and low-altitude tower en route
flights
Integrate Flight Management System generated vertical
trajectories to meet restrictions
Support holding patterns
Pluggable
37
Flight Management System
Generate vertical trajectories from route, time, speed,
and altitude restrictions
Model vertical profiles for jet, turboprop, and piston
aircraft
Interface with surface movement model at the runway
threshold
Pluggable
38
Concluding Remarks
Requirements are gathered from project investigators
and researchers and incorporated into development
Studies go on in parallel
ACES is in active development at one-year cycles
 Main trunk
 Branches of parallel development
39