The Modernized
NASPAC Simulation
Environment
Presented to: NAS-Wide Simulation & NextGen
workshop
By: Kimberly Noonan, Joseph Post
Date: December 10th, 2008
Federal Aviation
Administration
Your Father’s NASPAC
National Airspace System Performance Analysis Capability
•
The FAA’s standard system-wide model
•
Originally developed in late 1980s
•
Represents NAS as network of interconnected queues
– Airports
– TRACONs
– En route sectors
•
Discrete-event
– SIMSCRIPT II.5
– Fortran, C, Pascal pre-processors
•
Sun Solaris platform
•
Used mainly for investment analysis (i.e., cost-benefit analysis)
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
2
Legacy NASPAC Environment
TAF
OAG
ETMS
Future
Demand
Generator
Trajectory
Builder
ETMS
Itinerary
Purge
Routes
Fix
Inserter
4D
Trajectories
Sector
Crossings
Sector
Entry/Exit
Times
Core
Queuing
Model
Output
Trace
Files
Sector
Geometries
Sector
Capacities
Airport Capacities
Flow Restrictions
TAF = Terminal Area Forecast
OAG = Official Airline Guide
ETMS = Enhanced Traffic Management System
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Objectives of Modernized NASPAC
 Make available to more analysts and projects
 Maintain fast run time
 Incorporate traditional trajectory module
with fuel burn computation
 Automate airport weather scheduler
 Obtain modern, configuration-controlled, documented
source code
 Produce standard, analyst-friendly, repeatable output
 Validate
• Develop GUI and output visualization tools
• Facilitate Monte Carlo simulation
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Modernized NASPAC Environment
Delay Wx
Fuel Burn Rate
TAF
ETMS
Future
Schedule
Generato
r
Unconstrained
Traj.-Based
Forecast (2D)
Industry/
Regulatory
Response
Unsatisfied
Demand
Constrained
Traj.-Based
Forecast (2D)
Δ Fuel
Burn
4D
Trajectories
Legacy NASPAC
Sector Entry/Exit
Times
Itinerary
Generation
Fleet
Evolution
Java
Trajectory
Module
Fleet
Forecast
Wind
Field
Sector
Crossings
Sector
Geometries
Wx
MAP Values
The Modernized NASPAC Simulation Environment
10 December 2008
Flight Table
Output
Parser
Airport Table
Sector Table
Flight
Delays
Sector
Capacities
Pareto Curves
Wx = weather
TAF = Terminal Area Forecast
MAP = Monitor Alert Parameter
ETMS = Enhanced Traffic Management System
Core
Queuing
Model
Capacity
Scheduler
Airport Capacities
Flow Restrictions
Federal Aviation
Administration
5
Future Traffic Generation
Airport A
Airport B
Airport A
Airport B
TAF
Airport C
2007
ETMS
Airport D
Airport C
2010
Airport D
Forecast
• FAA airport forecasts are unconstrained
– Yield excessive and unrealistic future delays at some airports
• Estimated airport capacities used to constrain traffic growth
– Mimic operator and FAA response to large demand and capacity
imbalances
– Apply both schedule smoothing and trimming at 110 airports
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Itinerary Generation
• Constrained schedule consists of ETMS flight legs
– No tail numbers
• Create aircraft itineraries
– Link flight legs with same airline and aircraft type
– Minimize total fleet size, i.e. number of itineraries
– Respect schedule turn time constraints
ATL
A
Flight Leg arriving ATL
B Flight Leg Departing ATL
C
Flight Leg Departing ATL
Min schedule turn time
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Fleet Evolution
• Retire and replace aircraft with newer types
– minimize changes across seat-class/engine-type categories
• Consistent with APO and Mitre Fleet Forecast
• Domestic passenger and cargo airlines only
Forecast by category (2008)
0.35
0.30
% of Total Fleet
0.25
T<20
T020-049
T050-099
T100-150
J020-049
J050-099
J100-150
J151-210
J211-300
J301-400
J401-500
J500-601
J
0.20
0.15
0.10
0.05
0.00
2008
2009
2010
2011
2012
2013
2014
The Modernized NASPAC Simulation Environment
10 December 2008
2015
2016
2017
2018
2019
2020
Federal Aviation
Administration
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Java Trajectory Module
• Aircraft performance
– BADA 3.6 tables
• Waypoints / cruise alt.
– ETMS flight plan
• Arrival/departure fixes
– Assigned to flight path
• Wind data
– NCEP/NCAR
Global Reanalysis Model
• 4D track points computed at 1 min. intervals
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Airspace Modeled
939 airspace elements
The Modernized NASPAC Simulation Environment
10 December 2008
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Airports Modeled
• All IFR flights touching U.S. airspace are modeled
• Arrival/departure capacities for 110 airports included
– All other airports assumed to have infinite capacity
• VFR flights at 73 airports included
140
Arrlivals (/hr)
120
100
VMC
MMC
IMC
80
60
40
20
0
0
20
40
60
80
100
120
Departures (/hr)
OEP Airports
Other Airports
The Modernized NASPAC Simulation Environment
10 December 2008
Washington Dulles International
Airport Capacities
Federal Aviation
Administration
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Output Files
Input Files
Airport Capacity File (airportc)
ATO-P Input Schedule
pre-configuration File
Sector Capacity File (sector_sim)
sim-configuration File
Output Files
Flight
File
Perl
Arrival Trace File(t_arr)
Arrivals-Departures at Sink Trace File(t_snk)
At-Gate Trace File(t_agt)
Change Parameter File (change_apt)
Cross Arrival Fix-Departure Fix-Restriction Trace File(t_cnd)
Departure Trace File(t_dep)
Enter-Exit Sector Trace File(t_sec)
IFR Trajectories(traject)
JTM Bad Flights File
JTM Flight Map File
JTM Fuel Usage File
JTM Generate Itineraries Schedule
Pushback Trace File(t_pbk)
Script
s
The Modernized NASPAC Simulation Environment
10 December 2008
Oracle
Airport
File
Database
Sector
File
Federal Aviation
Administration
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Metrics
• Flights accommodated
– Flight trimming process
• Delay
–
–
–
–
Gate push-back
Departure runway/fix queuing
Sector queuing
Arrival fix/runway queuing
• Fuel Burn
– Origin to Destination
– US airspace
• CO2
– Jet A savings converted to CO2 using multiplier of 21.095 lb/gal
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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NASPAC Project Wiki
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Validation Process
Every new software release validated!
• Run simulation for eight historical days
– Demand variation
• Two days per season (1 weekend, 1 weekday)
– Weather variation
• Actual weather used for each day
• Distribution of surface and en route weather
• Compute flight time, delay, fuel burn metrics
• Compare validation metrics to observed system
response
– Ground Truth ≡ ASPM, ASQP, BTS databases
– Mean, variance
– Pooled, pair-wise statistics
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
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Airborne Delay, Daily Observations
Airborne Delay, v5d
Avg. Airborne Delay (min)
2.5
ASPM
NASPAC
Power (NASPAC)
Power (ASPM)
2.0
1.5
y = 8E-10x2.0557
1.0
y = 4E-09x1.8972
0.5
0.0
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
Flight Count
v5d
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Airborne Delay, OEP Airports
OEP 35 Airports, v5d
10
ASPM Airborne Delay (min)
8
6
4
y = 0.8636x + 0.6282
2
R = 0.3575
2
ORD
0
0
4
2
6
8
10
-2
-4
FLL
-6
NASPAC Airborne Delay (min)
19 Oct. 2006
The Modernized NASPAC Simulation Environment
10 December 2008
v5d
Federal Aviation
Administration
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Taxi-Out Delay, Daily Observations
Taxi-Out Delay, v5d
Avg. Taxi-Out Delay (min)
9
8
7
6
5
ASPM
NASPAC
4
3
2
1
0
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
Flight Count
v5d
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Push-Back Delay
ASPM Avg. Push-Back Delay (min)
Push-Back Delay, v5d
25
20
y = 3.1782x + 4.1314
R2 = 0.0429
15
10
5
0
0
0.5
1
1.5
2
2.5
3
3.5
NASPAC Avg. Push-Back Delay (min)
v5d
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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ETE Distributions, 19 Oct. 2006
ETE Distribution, v5d
30
Frequency (%)
25
20
15
NASPAC/JTM
ASPM
10
5
500
475
450
425
400
375
350
325
300
275
250
225
200
175
150
125
100
75
50
25
0
Estimated Time En Route (min)
v5d
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Airport Arrival Rate, 19 Oct. 2006
CLT Arrival Rates, 10/19/06, v5d
Arrivals (per 15 min. epoch)
20
18
16
14
12
NASPAC
ASPM
10
8
6
4
2
0
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Local Hour (EDT)
Charlotte-Douglas International Airport
The Modernized NASPAC Simulation Environment
10 December 2008
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v5d
21
Fuel Burn
FY 2007 Actual Fuel Usage
Domestic Commercial Flights 1
Actual Fuel: Total
2
FY 2007 Modeled Fuel Usage
10,843,220
13,594,891,330
Domestic Commercial Flights 3
10,563,035
Fuel 4
Nominal Taxi Out (gal)
310,763,808
Excess Taxi Out (gal)
50,646,405
0.4%
Nominal Airborne (gal)
12,742,782,169
93.6%
Excess Airborne (gal)
315,232,694
2.3%
Nominal Taxi In (gal)
116,787,683
0.9%
Excess Descent (gal)
82,043,414
0.6%
13,618,256,172
100.0%
29
2.3%
Model Fuel: Total
2.3%
Fuel per Flight
Nominal Taxi Out (gal / flt)
Excess Taxi Out (gal / flt)
5
0.4%
Nominal Airborne (gal / flt)
1,206
93.6%
Excess Airborne (gal / flt)
30
2.3%
Nominal Taxi In (gal / flt)
11
0.9%
7.8
0.6%
1,289.2
100.0%
Excess Descent (gal / flt)
Actual Fuel: per Flight
1,254
Notes:
5
Model Fuel: per Flight
2.8% diff.
1. Sum total of revenue departures in domestic service, reported by U.S. carriers filing DOT Form 41, Table T-1
2. Gallons of fuel used in domestic service, reported by U.S. carriers filing DOT Form 41, Table P-12a
3. Domestic flights, excluding the categories of "Fractional / Business", "GA", and "Military"
4. Nominal fuel use taken from ATO's JTM trajectory modeler.
Excess fuel used on taxi and enroute derived by multiplying minutes of NASPAC delays times BADA or ICAO fuel burn
Excess fuel used on descent taken from estimates of below-cruise vertical holding on domestic flights arriving at the OEP 35 airports
5. Excess minutes per flight on descent is the ratio of the excess time at the OEP airports to the number of total domestic flights.
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Conclusions
• Modernized model runs much faster, accessible to
more users, and easier to use
• Deterministic trajectory model provides easy
means of specifying flight trajectories
–
–
–
–
Uses standard Eurocontrol BADA data
Fuel burn computation integrated into trajectory model
Accommodates wind field
Achieves good accuracy in nominal flight time and fuel burn
• Airborne delays close to observed values
• Surface delays appear underestimated
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Next Steps
• Evolve International carrier fleet
• Enhance airport capacity model
– Incorporate additional airport pareto curves based on
alternative configurations and/or wind conditions
• Improve taxi-out delay
– Update departure fix en trail constraints
• Incorporate Traffic Flow Management (TFM)
– Ground Delay Programs
• Include Monte Carlo simulation capability
• Validation, validation, validation
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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Questions?
The Modernized NASPAC Simulation Environment
10 December 2008
Federal Aviation
Administration
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