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					                      NASA Research Results for
                       “4D-ASAS” Applications




                                        Presented by
                              David Wing (david.wing@nasa.gov)
                           Bryan Barmore (bryan.barmore@nasa.gov)
                                NASA Langley Research Center


ASAS Thematic Network 2 Third Workshop, Glasgow, Scotland           11-13 September 2006
                                                                                           1
                                             Research Premise:
                Distributing ATM Functions Results in Scalable ATM System

                                                                                 Distributed 4D Trajectory Management
    Strategic functions: ATSP                                                    ATSP sets strategic trajectory constraints
      Traffic flow management, resource scheduling                               Operator manages trajectory to meet them



    Local functions: 4D-ASAS-capable operator
      Flight safety, ATSP-issued constraint conformance,
      trajectory optimization

                                       Distributed                               Local situations and                Changes impacting
                                                                                 “no impact” changes                NAS resource usage
                              Flight     Air                                     are implemented by                     are coordinated
                              Crew
                                           Ground                                4D-ASAS aircraft                           strategically
                                              Traffic
                                                Management
                                                                                   Example local situation                          RTA
                       •   Information
                                                                                                                              unchanged
                       •   Decision making

                       •   Responsibility




 Presentation is on Two DAG-TM “4D-ASAS” Concepts
                                                                                                    Modified
 En-Route: Autonomous Flight Management                                                 Original    4D trajectory,
 Terminal Arrival: Airborne Precision Spacing                                         4D trajectory same strategic constraints



ATSP: Air Traffic Service Provider     RTA: Required Time of Arrival   4D-ASAS: Four Dimensional Airborne Separation Assistance Systems
                                                                                                                                            2
          Autonomous Flight Management
                              An En-Route/Transition 4D-ASAS Concept


                                                                           $+J
Integrated Operational Principles
 •   Performance-based operations                                    Cost control
 •   4D trajectory operations                                     Passenger comfort
 •   Non-segregated operations
                                                         IFR                               Autonomous Flight Rules
                                                       priority         Distributed             (AFR) Aircraft
                                                                        separation
                                                                        assurance
                                Hazard
Fleet management               avoidance

                                     AFR-managed
                                      trajectories     Priority              IFR
                Special Use                             rules            trajectory
                Airspace
                                                                        management         Instrument Flight Rules
                avoidance
                                                                                                 (IFR) Aircraft
                                                                   Maneuver
                                                                  restrictions


            Terminal area
           entry constraints       Levels of 4D-ASAS                IFR and AFR traffic
Terminal area   Q                     performance                    flow management              Air Traffic
                                                                                               Service Provider

                                                                                                            David Wing
                                                                                          NASA Langley Research Center
                                                                                                  david.wing@nasa.gov
                                                                                                                         3
            AFM Research Accomplishments
       NASA project-level accomplishments
    •      Operational concept description
    •      Feasibility assessment of airborne and integrated air/ground operations
    •      Feasibility assessment of ATSP operations
    •      Human factors assessment
    •      Life-cycle cost-benefit analysis
    •      Safety impact assessment
    •      Flight deck technology for autonomous operations
    •      ATSP decision support technology
    •      Experimental evaluation of integrated air/ground operations



       Langley contribution highlights
    1.     Developed flight-deck decision support toolset
           and supporting flight deck systems
           -- Autonomous Operations Planner (AOP)
    2.     Conducted 3 HITL simulation experiments
    3.     Performed 36-issue assessment of concept
           feasibility -- application of research analysis
           and domain expertise

                                                                                     4
                Autonomous Operations Planner
                NASA’s Research Prototype of 4D-ASAS En-Route Toolset


Principal Functions
• Strategic & tactical conflict
  detection & resolution                                               Crew
                                                                      inputs
• Conflict-free maneuvering support             AOP
• Flow constraint conformance                                            Command            Priority
• Airspace restriction avoidance                                          conflicts          rules

                                      Ownship                              Planning
                                       intent                              conflicts
Attributes                                            Intent-based
                                                         conflict
• Working software prototype w/                         detection
                                      Traffic                                            Conflict resolution
  ARINC 429 data-bus & 702a FMS                                   Provisional                    and
                                                                                                                  Conflict alerts
                                      intent                      (FMS/MCP)                                            and
  integration                                                       conflicts
                                                                                         trajectory planning
                                                                                                                   information
• CD&R alerting is RTCA SC186                           Maneuver
  ACM-WG compliant                                      restriction
                                      Ownship          information
• Simultaneously meets traffic,        state
  airspace, user, and flow                            State-based
                                                                                Blunder protection and
                                                        conflict
  management constraints (RTA)                         detection
                                                                                    collision data

• Performs trajectory optimization    Traffic
  as part of conflict resolution       state
                                                                                        ATC flow management
• Works within and ‘across’ normal                                                     constraints and airspace
  autoflight modes, and within                                                                constraints

  aircraft performance limits

                                                                                                                                    5
              Pilot-Only Simulation Experiments:
                        Study of Tools, Procedures, Hazards

                                          Scenario Design
                                          Conventional traffic conflicts
                                             –   Lateral & vertical
                                             –   State & intent
                                          Unconventional traffic conflicts
                                             –   Blunders
                                             –   Pop-up separation loss
                                             –   Meter-fix conflicts
                                          Constraints
                                             –   ADS-B surveillance limitations
                                             –   Airspace restrictions
                                             –   Required Time of Arrival


                                          Variables studied
                                             –   Traffic density
                                             –   Use of intent data
                                             –   Conflict resolution method
                                             –   Lateral separation standard
                                             –   Airspace restrictions
                                             –   Priority rules


  Studies resulted in significant gains in understanding of AFR operations feasibility,
operational sensitivities, human factors design, and requirements for tools & procedures
                                                                                           6
                      Pilot-Only Simulation Experiments:
                                                     Sample Results

                   Aircraft                    Aircraft                                                met all       missed one            missed multiple
Over-Constrained




                      A                           B
                                        SUA                                                                      No priority rules         With priority rules




                                                                             Constraint Conformance
  Trajectories



                                                                                                      100%




                                                                                                                                                Goal



                                                                                                                                                                         Goal
                                                                                                      80%
                              SUA
                                              SUA
                                                                                                      60%




                                                                                                                                                              Result: Better
                                                                                                                                                              predictability
                    SUA                                                                               40%

                                                    Crossing Assignment                               20%
                                                       RTA <30 seconds
                   Identical crossing                                                                  0%
                                                         Altitude < 500 ft                                         Left    Right              Left    Right
                   assignments                         Position < 2.5 nm                                         aircraft aircraft          aircraft aircraft



                                                                                                                                              59 data runs
Propagation
  Conflict




                                                                                                                                                  No Events
                                                                                                                                                              effect prevented
                                                                                                                                                              Result: Domino
                                                    Resolution Method
                                                    Tactical: open loop
                                                 Strategic: closed loop
                                                Modified: pilot override                                               Resolution method
                                                                                                                                                                                 7
                     Integrated Air-Ground Experiment:
                            Langley-Ames Experimental Evaluation

Addressed 2 key feasibility issues:
       – Mixed Operations: Investigate safety and efficiency in high density sectors
         compared to all managed operations
       – Scalability: Investigate ability to safely increase total aircraft beyond controller
         manageable levels. Number of managed aircraft remains at or below current
         high-density levels.

                                                          Overflights                                        4 test conditions
                                                          Arrivals                    Autonomous                3 traffic levels

                                Ghost North
                                                                                      Managed                             L3
          Amarillo
           High
                                                                                                               L2
                                                                             T1
                                                Ardmore
                        Wichita Falls             High
                           High                                                               L1      L1
         Ghost South                    Bowie
                                         Low                                 T0
      Fort Worth Center (ZFW)
                                  BAMBE
                            Ghost DFW TRACON

                                                                                              C1      C2       C3         C4

• 22 commercial airline pilots (20 single pilots + 2                    • T0: ≈ current monitor alert parameter
  pilot crew in high fidelity simulator)                                • T1: approximate threshold above which managed only
• 5 professional air traffic controllers (1 per sector +                  operations will definitely fail (determined by Ames study)
  1 tracker)                                                            • Only overflights were increased (arrivals held constant)

                                                                                                                                       8
                            Langley Aircraft and Ames Controller
                                      Sample Results

                 Meter fix conformance for arrivals                                     Controller workload assessment
                                                                                    7
                                 Time    Altitude    Speed        High                                               C1   C2   C3      C4
                                                                                    6
                      100




                                                                  Workload Rating
                                                                                    5
Percent Conformance




                      80

                      60                                                            4


                      40                                                            3


                      20                                                            2


                       0                                          Low 1
                            C1      C2               C3      C4                          Amarillo   Ardmore   Wichita Falls    Bowie
                                    Increasing Traffic                                                  Controller
                                         Condition




• Pilots mainly able to meet constraints                              • Lower workload for all mixed conditions
• Some pilot entry error (RTA into FMS)                               • Traffic levels at C3 and C4 not
• No apparent performance degradation                                   considered manageable if all aircraft IFR
  as traffic level increased


                                                                                                                                            9
       AFM Feasibility Assessment Activity
•   Team analysis of 36 feasibility questions
    – Distributed operations, air/ground integration, strategic & local TFM, flight crew
      responsibilities, airborne equipage, CNS
    – Evaluations based on literature search, research results, operational experience
      and judgment


•   Sample questions:
    – Is the distributed AFR network vulnerable to system-level or cascading component
      failures?
    – Within what limits do AFR aircraft have the ability to adapt to changes in the airport
      acceptance?
    – Can airborne conflict management be performed in all ownship flight guidance
      modes?
    – Can AFR operations accommodate a range of RNP capabilities?


•   Conclusion:
    – Feasible at the integrated-system / laboratory-simulation maturity level
    – Further technical progress requirements identified
    – Sample challenges:
         Accommodating prediction uncertainties    Flow-constrained descents
         Convective weather interaction            Failure modes
         Traffic complexity management             Complex AFR/IFR interactions

                                                                                               10
Airborne Precision Spacing
   A Terminal Arrival 4D-ASAS Concept




                                                   Dr. Bryan Barmore
                                        NASA Langley Research Center
                                            bryan.barmore@nasa.gov
Airborne Precision Spacing

            ADS-B-enabled operation in which the
            ATSP assigns speed management for
            spacing to the aircraft
            Goal is to increase runway
            capacity by increasing the precision
            and predictability of runway arrivals
              ATSP manages traffic flow, ensures
              separation and determines the landing
              sequence
              Pilots precisely fly their aircraft to
              achieve ATSP-specified spacing goal
            A single strategic clearance reduces
            radio congestion and workload for
            both ATSP and pilots


                                                       12
                  APS Flight Deck Automation
Computes relative ETA at threshold
Provides speed guidance to             Adjusts for dissimilar final
   achieve desired relative ETA           approach speeds
Safe merging is a consequence of       Corrects speed if necessary to
   beginning spacing operations           prevent separation violations
   early                               Gain scheduling to enhance
Spacing interval can be customized        stability of a aircraft stream
   pair-wise to account for wake       Respects aircraft configuration
   vortex hazard and other                limits for speed changes
   constraints


                  Lead:
                  time to go = 22:15
                30 seconds early
 Target:          at threshold
 90 secs          Slow down 5
                      knots

                 Ownship:
                 time to go = 23:15

                                                                           13
   Human-in-the-Loop Evaluation of APS

Chicago O’Hare Flight                   Medium fidelity simulation results
Evaluation
 Three equipped aircraft including
   NASA B757
 Wind shifts of 230º or more seen on
  base and final
 Flight performance – 8 sec
 Simulation performance – 2 sec
Medium fidelity simulation
 Merging and in-trail operations
 9 aircraft stream (6 subject pilots)
 No dependence on airspace design,
  type of operation or location in
  stream
 15-20 minute flight times
                                                                             14
Fast-time Simulations

               DFW airspace with three merging
                streams
               Each data run had a stream of 100
                aircraft / 40 repetitions per
                condition
               Wide range of aircraft types and
                performance (BADA model)
               Precision of approximately 2 sec
                under nominal conditions
               Challenges for significant initial
                spacing deviation; wind forecast
                errors and limited ADS-B range
               Knowing final approach speed gives
                significant improvement in spacing
                precision
               Improvements being made for wind
                 updating and setting initial spacing
                 requirements

                                                        15
                            CDA with Spacing
Continuous Descent Approaches offer a
  fuel and time efficient descent while
  reducing ground noise and
  environmental pollutants
However, ATSP must be largely “hands-
  off” resulting in loss of capacity to
  maintain safety
By including airborne spacing we can
  realize the majority of the CDA benefits
  while maintaining capacity levels
The ability to make only minor speed adjustments during the procedure allows
  the flight crew to stay close to the optimal CDA while maintaining spacing with
  other aircraft
NASA is currently working with the FAA, other research organizations, a major
 airline and avionics vender to develop and implement merging & spacing

                This is seen as a first step to implementing airborne spacing in
                             large, complex terminal environments
                                                                                    16
Preliminary Merging and Spacing
       Simulation Results

                 Four CDA routes into DFW
                 350 nm routes
                 Merges at cruise, downwind, base
                 Nominal winds, initial spacing deviation
                 Studied several disruptive events
                    (not presented here)
                 Results for nominal case: 0.21.3 sec
                    for disturbances: -0.94.3 sec
                            Separation at merge point




                                                            17
        Current and Future NASA Research
               Related to 4D-ASAS

• Safety assessments of distributed airborne separation
   – Batch study on distributed strategic conflict management
• Traffic complexity management through distributed
  control of trajectory flexibility
   – Development of flexibility metric, preservation function
   – Trajectory constraint minimization
• Early implementation applications
   – Oceanic In Trail Procedure
   – Merging and spacing with continuous descents
• Airborne Precision Spacing in super-density terminal
  arrival operations


                                                                18
Thanks for your attention.


  (Back-up charts follow)




                             19
                               En-Route
                      Safety Impact Assessment
•   Study performed by Volpe National Transportation Systems Center, Oct. 2004
     –   To provide NASA with information on potential safety impacts and risks that can be
         addressed during concept development, simulation, and testing
     –   Approach: (1) Task-based analysis and (2) Simulation results analysis

•   Findings
     –   Identified no safety showstoppers, several positive safety impacts, and several safety issues
         recommended for further research
     –   Concept at early stages of R&D, too soon to determine safety relative to the current system
     –   Ultimate assessment requires iterative safety analyses, determination of safety and
         performance requirements for systems and operators, and extensive testing

•   Safety Issues Recommended for Further Research (highlights)
     –   Roll of automation: Need stringent criteria for availability, integrity, and accuracy
     –   Unambiguous identification (air & ground) of AFR vs. IFR status
     –   Determine need for ATSP awareness of AFR traffic, AFR-IFR conflicts
     –   AFR awareness of AFR-IFR conflicts; AFR/ATSP coordination for short-term alerts
     –   Upper limit of distributed authorities (AFR) for safe operations – complexity management*
     –   AFR-to-IFR transition in non-normal situations; significant rates of metering non-conformance
     –   Impact of degraded or erroneous intent information
     –   Flight crew workload in descent
     –   Preclusion of conflict propagation*
                                                                      * New R&D activities currently in progress
                                                                            or planned to address these issues
                                                                                                               20
                                              Safety Design
          AOP’s Layered Approach to Distributed Separation Assurance


            Pre-alert           Level 1 (L1) alert             L2 alert                                                  L3 alert
                                   (low level alert)          (conflict alert)                                          (NMAC alert)



                                                                                                                              ACAS

                                                                                          Implicit coordination
                                                               Strategic &
                                     Right-of-way              tactical CR                                                 L3 alert
           Continuous                   rules                                                                             (NMAC alert)
           surveillance
                                                                                                                         X
   Display filtering                                                                        L2 alert          X
                                                                                           (conflict alert)
  Conflict prevention
                                                                                                                       Nearby aircraft
Flexibility preservation                                            L1 alert
                                                                  (low level alert)                                   Maneuver
                                                                                                                  restriction alerting
                                           L0 alert
                                        (traffic point out)
                                                                                          Additional Protective Factors
                                                                                      •   Long look-ahead time horizon
                    Pre-alert
                                                                                      •   On-condition intent-change broadcast
                                                                                      •   Intent-based automated conflict detection
                                                                                      •   Alert-based procedures
                                                                                      •   Rapid-update state surveillance
Protection layers
                                                                                      •   Human/automation redundancy
                                                                                                                                         21
                     4D-ASAS Issues of Concern
                         For Discussion and Possible Study

•   Socio-political acceptability
     –   Social acceptance that a distributed-authority system is safe regardless of technical proof?
     –   Political resistance to implementation of distributed system (users and service providers)?
•   Destabilization from gaming
     –   Can this be mitigated using slot management?
•   Performance-achievement incentive
     –   Is there sufficient incentive for users to always want to equip for higher ATM performance?
•   Short-distance flight benefits
     –   Are there sufficient degrees of freedom?
•   Departure constraints impact on performance
     –   Will users have sufficient departure-time control to achieve benefits?
•   Retrofit potential
     –   Does forward-fitting meet the demand?
     –   Are retrofit options technically feasible, cost-effective, and beneficial?
•   Mandate impact
     –   What is the user cost/benefit impact if 4D-ASAS is mandated?




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