Joint NASA Ames/Langley Experimental Evaluation of ... - ATM Seminar

Joint NASA Ames/Langley Experimental Evaluation of Integrated Air/Ground Operations for En Route Free Maneuvering Richard Barhydt NASA Langley Research Center

Parimal Kopardekar NASA Ames Research Center

DAG-TM Team Members (Vernol Battiste, Nathan Doble, Walter Johnson, Paul Lee, Thomas Prevot, and Nancy Smith) NASA Ames and Langley Research Centers Explore. Discover. Understand.

Distributed Air/Ground Traffic Management (DAG-TM) En Route Free Maneuvering Underlying premise: • Large improvements in system capacity, airspace user flexibility, and user efficiency can be enabled through: • Sharing information about flight intent, traffic, and the airspace environment – Collaborative decision making among system participants – Distributing decision authority to the most appropriate decision maker • One who has the most relevant information about problem • Breaking apart one large complex problem into series of smaller, more manageable problems Explore. Discover. Understand.

DAG-TM Operational Environment Concept Integrates:

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Mixed operations Operational constraints User flexibility

Cost management, Passenger comfort

IFR priority

Autonomous (AFR) Aircraft Aeronautical Operational Control

Airborne separation

Hazard avoidance

Fleet management

Priority rules

Special Use Airspace avoidance

Managed (IFR) Aircraft IFR trajectory management

Maneuver restrictions

Crossing restrictions

Terminal area

User-determined optimal trajectory User-determined optimal trajectory

Explore. Discover. Understand.

IFR and AFR traffic flow management

Air Traffic Service Provider

Experiment Motivation and Design •

Experiment designed to address 2 key feasibility areas for DAG-TM: – Mixed Operations: Investigate safety and efficiency of mixed AFR/IFR operations in high density sectors compared to all managed operations. – Scalability: Investigate ability to safely increase total number of aircraft in sector (beyond controller manageable levels) if number of managed aircraft remains at or below current high-density levels. • •

Autonomous Managed

L3 L2

T1 L1

•

L1

• •

T0

C1

C2

C3


C4

4 conditions, 3 traffic levels Only overflights increased (arrivals held constant) Within-subjects design for subject pilots and controllers T0: ≈ current monitor alert parameter T1: threshold above which managed only operations will definitely fail – Determined by prior Ames study

Experiment Method •

Simulation facilities – Langley – PC-based flight deck stations – Ames – PC-based controller and flight deck stations, high fidelity flight simulator

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Participants – 22 commercial airline pilots (12 Langley, 10 Ames: 8 single pilots + 2 pilot crew in high fidelity simulator) – 5 professional air traffic controllers (1 per sector + 1 tracker)

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Airspace – Modified after DFW – Overflights • Ardmore, Amarillo – Arrivals • 2 streams • Converged at BAMBE

Overflights Arrivals

Ghost North

Amarillo High

Ardmore High

Wichita Falls High Bowie Low

Ghost South Fort Worth Center (ZFW)

BAMBE Ghost DFW TRACON


Air and Ground Capabilities •

Airborne capabilities: – Common features for all aircraft: • Controller Pilot Data Link Communication (CPDLC) • AFR aircraft – self separation capability and ability to meet meter fix constraints (waypoint speed, altitude, and time) – Langley and Ames implemented different aircraft simulations, flight deck decision support tools, Automatic Dependent Surveillance Broadcast (ADS-B models)

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Ground capabilities – Meter fix arrival scheduler • Provided slots for AFR traffic to merge with IFR • Automatically uplinked Required Time of Arrival (RTA) to all AFR aircraft and assigned Scheduled Time of Arrival (STA) to IFR aircraft upon crossing freeze horizon (160 NM from meter fix)

– Conflict detection for IFR-IFR conflicts (15 minute time horizon) – As safety back-up, controllers notified of AFR-IFR conflicts within 3 minutes of predicted separation loss (AFR responsible) Explore. Discover. Understand.

Operations and Scenarios •

Participant responsibilities: – AFR pilots: maintain separation (5 NM/1000 ft) from all other traffic, meet assigned meter fix constraints (arriving aircraft), not maneuver in a way that would create a near-term conflict – IFR pilots: comply with controller instructions (consistent with current day operations) – Controllers: provide traffic separation for IFR aircraft, give vector and speed commands to IFR aircraft in order to meet STA • Not responsible for resolving AFR-AFR or AFR-IFR traffic conflicts.

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Scenarios – Ames and Langley subject pilots kept in different sectors due to various system and experiment design differences. • Results should not be compared between each Center. – Each subject pilot flew two en route and two arrival segments per experimental condition with arrivals being terminated at meter fix. – Controllers assigned to same sector throughout experiment


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6 5 4 3 2 1 0 IFRIFR IFRIFR AFRIFR AFRAFR IFRIFR AFRIFR AFRAFR IFRIFR AFRIFR AFRAFR

Frequency of Separation Violations

Langley Flight Deck Results

C1

C2

C3

C4

Traffic Level

Time

Altitude

•

Speed

Percent Conformance

100 80 60 40 20 0 C1

C2

C3 Condition


C4

Separation violations – System error contributed to 11/13 (mainly due to software bug that prevented state-based conflict alert from being issued). – Procedural/training issue contributed to 2/13 – 1 due to complex traffic situation Meter fix conformance (arriving aircraft) – Pilots mainly able to meet constraints – 2/4 time deviations due to pilot entering wrong RTA – No apparent performance degradation as traffic level increased

Langley Flight Deck Results •

Scripted conflicts – Planned AFR/IFR conflict for Langley AFR subject pilots – Included IFR/IFR conflict in Langley sector – Conflicts scaled locally to match scenario traffic level

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Results (AFR subject pilots) – Resolution times before predicted Loss of Separation (LOS) changed little as function of traffic level – 7 resolution maneuvers resulted in additional conflict • All at highest traffic level • 6/7 – pilot maneuvered without using resolution guidance

Flank 1, -1000 ft (All Scenarios)

10 min alert for all planned conflicts

– 22-30% of conflicts required multiple resolutions • Little change with traffic level 60°

Intruder

Flank 3, co-altitude (C4 Scenarios)

Flank 2, +1000 ft (C3, C4 Scenarios)


Subject Pilot / Pseudo Pilot

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Results (controllers, IFR/IFR) – Resolution times before predicted LOS do not appear to depend on traffic level – Times comparable to all IFR condition (C1)

Ames Flight Deck Results •

No separation violations for any Ames subject pilot Time

Altitude

Speed

•

Meter fix conformance (arriving aircraft) – Constraints met in almost all cases – No apparent performance degradation as traffic level increased

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Conflicts dectected – 122/139 total conflicts detected more than 4 minutes to predicted LOS – All late alerts due to near-term conflict caused by another aircraft

Percent Conformance

100 80 60 40 20 0 C1

C2

C3

C4

Condition

50 Bet ween 2 and 4 M inut es

Frequency

40

Great er t hean 4 M inut es

30 20 10 0 C2

C3

C4

Condition


Ames Flight Deck Results •

Conflicts resolved vs. time – Most conflicts resolved at least 4 min prior to predicted LOS – Only 2 resolved less than 2 min before predicted LOS (software error contributed to both)

Frequency

Under 2 Minutes 50

Between 2 and 4 Minutes

40

Greater thean 4 Minutes

30

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Resolutions based on priority – Ames incorporated priority flight rules. – AFR aircraft almost always maneuvered for AFR-IFR conflicts (IFR never burdened).

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Pilot preferences

20 10 0 C2

C3

C4

Condition

AFR Preferred Overall Safety


Overall Workload

IFR Preferred Time Conformance

Overall Situation Awareness

Ground-side and Controller Results

6 5 4 3 2 1 0

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Separation violations – As discussed, most AFR/AFR and AFR/IFR LOS events due to system or software error. – 6/7 IFR/IFR LOS events due to pseudo-pilot or pseudocontroller procedural error. – Results suggest that increased traffic levels do not degrade controller’s ability to separate IFR traffic.

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Meter fix conformance (arriving aircraft) – Neither mixed operations, nor additional overflights appeared to affect meter fix conformance

IF R IF R IF R IF R AFRIF R AFRAFR IF R IF R AFRIF R AFRAFR IF R IF R AFRIF R AFRAFR

F re q u e n c y o f S e p a ra tio n V io la tio n s

Data provided for subject pilot controlled (Ames and Langley) and IFR aircraft.

C1

C2

C3

C4

Traffic Level Time

Altitude

Speed

100

Conformance (%)

•

80 60 40 20 0 C1

C2

C3

Traffic Condition


C4

Ground-side and Controller Results 7

C1

C2

C3

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Controller workload assessment – Lower workload for all mixed operations conditions, despite significantly higher traffic levels (~2*current day capacity at C4) – (Traffic levels at C3 and C4 not considered manageable if all aircraft IFR).

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Controller safety assessment – Controllers ranked all managed condition as safest and highest traffic level AFR/IFR condition as least safe. – Most common concern related to AFR/IFR conflicts.

C4

Workload Rating

6 5 4 3 2 1

Amarillo

Ardmore

Wichita Falls

Bowie

Controller

Average Priority Ranking

0.7

C1

0.6

C2

C3

0.5 0.4 0.3 0.2 0.1 0

Amarillo

Ardmore

Wichita Falls

Controller


Bowie

C4

• Controllers felt compelled to act even though not required. • Late resolutions by and unclear intent from AFR aircraft.

Conclusions • • • • •

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DAG-TM En Route Free Maneuvering has potential to greatly increase capacity, provided safety concerns can be addressed. Significantly higher numbers of aircraft can be added without degrading meter fix conformance, controller, or pilot workload. Controller workload appeared to correlate primarily to number of managed aircraft. Pilots felt comfortable with self-separation while managing constraints. Unresolved near-term AFR-IFR conflicts was biggest safety problem. – Events increased dramatically for pseudo-pilots at higher traffic levels (were controlling more aircraft), little change for subjects. – Shows need for improved integration and compatibility between air/ground automation and procedures. – Clear guidance and shared intent required for near-term conflicts. Follow-on research to investigate harmonized trajectory exchange, improved air/ground system and procedural compatibility, transitional airspace, system failures.
