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Arrival Scheduling with Shortcut Path Op6ons and Mixed Aircra: Performance
Shannon Zelinski and Jaewoo Jung NASA Ames Research Center
Time-‐Based Arrival Management
Fixed Path Speed Control
Improved schedule conformance
More precise scheduling Tighter spacing
Reduced flexibility
More accurate trajectory predic6ons
• Strategic use of path op6ons – Delay absorp6on
[HaraldsdoOr et al. 2009]
– Mixed aircra: performance [Uebbing-‐Rumke et al. 2011, Thipphavong et al. 2013]
• Tac6cal use of path op6ons – Rescheduling for off-‐nominal recovery
[Callan6ne et al. 2011, Swenson et al. 2012]
– Shortcut path op6ons for schedule conformance [Zelinski 2013]
Time-‐Based Arrival Management Path Op6ons
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path op6ons to tac6cally recover from schedule disturbances.
– Poten6al to increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6al to incen6vize aircra: capable of high arrival 6me precision.
Shortcut Path Op6ons [Zelinski 2013]
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path op6ons to tac6cally recover from schedule disturbances.
– Poten6al to increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6al to incen6vize aircra: capable of high arrival 6me precision.
Shortcut Path Op6ons [Zelinski 2013]
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path op6ons to tac6cally recover from schedule disturbances.
– Poten6al to increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6al to incen6vize aircra: capable of high arrival 6me precision.
Shortcut Path Op6ons [Zelinski 2013]
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path op6ons to tac6cally recover from schedule disturbances.
– Poten6al to increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6al to incen6vize aircra: capable of high arrival 6me precision.
Shortcut Path Op6ons [Zelinski 2013]
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path op6ons to tac6cally recover from schedule disturbances.
– Poten6al to increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6al to incen6vize aircra: capable of high arrival 6me precision.
Shortcut Path Op6ons [Zelinski 2013]
• Tac6cal use of shortcut
• Schedule to a nominal path (not the shortest). – Reserve shortcut path to recover from schedule disturbances. – May increase throughput 11% during high traffic demand.
• Schedule to shortest path op6on. – Depend on schedule slack to absorb schedule disturbances. – Poten6ally incen6vize high arrival 6me precision aircra:.
Shortcut Path Op6ons [Zelinski 2013]
• Can tac6cal shortcuts enhance 6me-‐based arrival management?
• Can tac6cal shortcuts incen6vize early equipage of arrival 6me precision capability?
Objec6ve Research Ques6ons
Apply concept to terminal metering modeled at Los Angeles Interna4onal Airport.
Schedule arrival 4me precision equipped aircra; with reduced buffers.
• Route modeling • Arrival scheduler • Simula6on • Experiment Setup • Experiment Metrics • Results • Conclusion
Outline
Route Modeling Baseline Arrival Rou6ng
turboprop route
jet route
meter fix
runway threshold
merge point
Route Modeling
decision point
merge point
shortcut
bypassed merge point
Shortcut Path Op6ons • All shortcuts may be used tac6cally.
• Only Final shortcuts may be used strategically by the scheduler.
Final shortcut
Feeder
Route Modeling
N Final
S Final
NE Feeder
SE Feeder
S Feeder
NW Feeder
Arrival Scheduler Mul6-‐Point Scheduler
Route (meter fix to runway)
Blocked Times (per scheduling point)
Travel Time Ranges (per route segment)
New Flight (meter fix ETA)
[Meyn, 2010]
Compute schedule for all route op6ons. Assign route producing earliest runway STA.
Solu6on Set (feasible STA windows at each point)
Schedule (earliest STAs at each point)
Arrival Scheduler Mul6-‐Point Scheduler
Route (meter fix to runway)
Travel Time Ranges (per route segment)
New Flight (meter fix ETA)
[Meyn, 2010]
Compute schedule for all route op6ons. Assign route producing earliest runway STA.
Solu6on Set (feasible STA windows at each point)
Schedule (earliest STAs at each point)
Blocked Times = Required Separa6on + Scheduling Buffer
Buffer depends on: • Delivery precision • Shortcut availability
Blocked Times (per scheduling point)
Arrival Scheduler Buffers
• Delivery Precision – Required Time of Arrival (RTA): σ = 4.5 sec – Controller Managed Spacing (CMS): σ = 9 sec
• Shortcut Availability – Available: buffer = 1.1σ – Not available: buffer = 1.8σ
[Zelinski 2013]
[Klooster et al. 2009, Swieringa et al. 2014]
[Kupfer et al. 2011, Thipphavong et al. 2013]
0 2 4 6 8 10 12 14 16 18
Scheduling Buffer
RTA CMS
RTA CMS
Shortcut Not Available
Shortcut Available
seconds
Arrival Scheduler Example
CMS
9.9 sec buffer
9.9 sec buffer
0 2 4 6 8 10 12 14 16 18
Scheduling Buffer
RTA CMS
RTA CMS
Shortcut Not Available
Shortcut Available
seconds
16.2 sec buffer
16.2 sec buffer
Arrival Scheduler Example
CMS
9.9 sec buffer
9.9 sec buffer
16.2 sec buffer
9.9 sec buffer
0 2 4 6 8 10 12 14 16 18
Scheduling Buffer
RTA CMS
RTA CMS
Shortcut Not Available
Shortcut Available
seconds
Arrival Scheduler Example
CMS
9.9 sec buffer
16.2 sec buffer
16.2 sec buffer
0 2 4 6 8 10 12 14 16 18
Scheduling Buffer
RTA CMS
RTA CMS
Shortcut Not Available
Shortcut Available
seconds
Scheduled Final Shortcut
Arrival Scheduler Example
RTA
8.1 sec buffer
0 2 4 6 8 10 12 14 16 18
Scheduling Buffer
RTA CMS
RTA CMS
Shortcut Not Available
Shortcut Available
seconds
Scheduled Final Shortcut
4.9 sec buffer
8.1 sec buffer
• Actual Time of Arrival (ATA) Errors: – Meter fix error σ = 60 seconds for all aircra:. – All other error σ = 4.5 (RTA) or 9 (CMS) seconds.
• Speed control range: – Speed up by 5% – Slow down by 10%
• Preliminary ATA moved back if violates spacing requirements.
• All late flights use shortcut.
Simula6on
• Fleet mix and meter fix distribu6on: Based on historical traffic
• RTA equipage ra6o: Ranged from 0 (all CMS) to 1 (all RTA) in 0.1 increments
• Traffic scenarios: – 2-‐hours, 144 flights each – 1000 scenarios per RTA equipage ra6o
• Rou6ng scenarios: – Baseline – Shortcut
• Simula6ons: 100 varia6ons per traffic/rou6ng scenario
Experiment Setup
• Throughput: – Counts of runway arrival 6mes during 2nd hour of each simula6on.
– Demand (ETA), Scheduled (STA), and Actual (ATA). • Scheduled Delay: – Total delay (STA-‐ETA) segregated into Center, path, and speed delay.
– Averaged across all 144 flights in each simula6on.
Experiment Metrics
Center Delay Path Delay Speed Delay
Terminal Airspace Delay
Total Delay
• Speed Control Workload Percent instances when preliminary ATA violates spacing requirements and must be moved back.
• Shortcut Usage – Percent scheduled shortcuts – Percent shortcuts used tac6cally
• Schedule Conformance – Error (ATA-‐STA) at each coordina6on point – Mean and Standard error
Experiment Metrics
Results -‐ Throughput
68#
69#
70#
71#
72#
73#
0# 0.1# 0.2# 0.3# 0.4# 0.5# 0.6# 0.7# 0.8# 0.9# 1#
RTA equipage ra6o
Average flights
per hour
Demand
Scheduled
Actual
Baseline
Shortcuts
Shortcuts achieved higher throughput at lower RTA ra6o.
Results – Scheduled Delay
0"
30"
60"
90"
120"
150"
180"
210"
0" 0.1" 0.2" 0.3" 0.4" 0.5" 0.6" 0.7" 0.8" 0.9" 1"
• Most addi6onal delay applied to Center.
• Traffic scenarios are satura6ng the terminal.
RTA equipage ra6o
Speed
Path
Baseline
Average scheduled delay
(seconds)
Shortcuts
Results – Speed Control Workload
54%$
56%$
58%$
60%$
62%$
64%$
0$ 0.1$ 0.2$ 0.3$ 0.4$ 0.5$ 0.6$ 0.7$ 0.8$ 0.9$ 1$
Shortcut
Baseline
Percent ATA adjustments
RTA equipage ra6o
• Shortcuts reduce speed control workload 8-‐10%. • Workload benefit persists for high RTA equipage ra6os.
10% 8%
North
South
0%#
2%#
4%#
6%#
8%#
10%#
12%#
14%#
16%#
18%#
0# 0.1# 0.2# 0.3# 0.4# 0.5# 0.6# 0.7# 0.8# 0.9# 1#
North shortcut
South shortcut
Percent scheduled shortcuts
RTA equipage ra6o
RTA
CMS
• Low scheduled shortcut usage. • Usage increases with RTA ra6o. • RTA shortcut usage similar to CMS.
Results – Shortcut Usage (Scheduled)
Results – Shortcut Usage (Tac6cal) High tac6cal shortcut usage. Why? • High meter fix uncertainty and cascading delays.
• High traffic load with few gaps.
• Asymmetric speed control authority.
N Final
S Final
NE Feeder
SE Feeder
S Feeder
NW Feeder
Tac6cal Shortcut Usage
Percent used of available 50%$60%$70%$80%$90%$100%$
Tac6cal Shortcut Availability
No. per simula6on
S Final S Feeder N Final
NW Feeder SE Feeder NE Feeder
0" 10" 20" 30" 40" 50"
Results – Schedule Conformance
1
2 3 4 5 6
Shortcut rou6ng is more effec6ve: • Mi6ga6ng increasing mean error • Reducing standard error
Posi6ve Error = Late
0"
10"
20"
30"
1" 2" 3" 4" 5" 6"
Mean Error Shortcut Baseline
sec
Error = ATA-‐STA
0"
10"
20"
30"
40"
50"
60"
1" 2" 3" 4" 5" 6"
Standard Error
sec
Can tac6cal shortcuts enhance 6me-‐based arrival management?
• Enhancements: – Increased schedule conformance – Tighter slots
• Benefits: – Increased throughput – Reduced delay – Reduced workload
• Usage lesson learned: Reserving shortcuts for tac6cal use makes the schedule more robust to disturbances.
Conclusion -‐ Research Ques6ons Answered
Yes
Can tac6cal shortcuts incen6vize early equipage of arrival 6me precision capability? • System benefits increased with equipage but … • RTA equipped aircra: had no significant advantage over unequipped.
Conclusion -‐ Research Ques6ons Answered
Not much
Ques6ons?