1 Presented by David Wing Bryan Barmore NASA Langley Research NASA Research Results for “4D-ASAS” Applications ASAS Thematic Network 2 Third Workshop, Glasgow, Scotland September 2006

2 Research Premise: Distributing ATM Functions Results in Scalable ATM System Strategic functions: ATSP Traffic flow management, resource scheduling Local functions: 4D-ASAS-capable operator Flight safety, ATSP-issued constraint conformance, trajectory optimization Presentation is on Two DAG-TM “4D-ASAS” Concepts En-Route: Autonomous Flight Management Terminal Arrival: Airborne Precision Spacing ATSP: Air Traffic Service Provider Aeronautical Operational Control Air Traffic Service Provider Flight Crew Information Decision making Responsibility Distributed Air Ground Traffic Management Original 4D trajectory Modified 4D trajectory, same strategic constraints RTA unchanged Distributed 4D Trajectory Management ATSP sets strategic trajectory constraints Operator manages trajectory to meet them Distributed 4D Trajectory Management ATSP sets strategic trajectory constraints Operator manages trajectory to meet them Local situations and “no impact” changes are implemented by 4D-ASAS aircraft Changes impacting NAS resource usage are coordinated strategically Example local situation 4D-ASAS: Four Dimensional Airborne Separation Assistance SystemsRTA: Required Time of Arrival

3                 Instrument Flight Rules (IFR) Aircraft          Hazard avoidance Fleet management Priority rules Maneuver restrictions IFR priority Distributed separation assurance Terminal area Terminal area entry constraints IFR and AFR traffic flow management IFR trajectory management Cost control Passenger comfort AFR-managed trajectories $ + Autonomous Flight Management An En-Route/Transition 4D-ASAS Concept Levels of 4D-ASAS performance Integrated Operational Principles Performance-based operations 4D trajectory operations Non-segregated operations Integrated Operational Principles Performance-based operations 4D trajectory operations Non-segregated operations Autonomous Flight Rules (AFR) Aircraft Air Traffic Service Provider Special Use Airspace avoidance David Wing NASA Langley Research Center 

4 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

5 Strategic & tactical conflict detection & resolution Conflict-free maneuvering support Flow constraint conformance Airspace restriction avoidance Principal Functions Autonomous Operations Planner NASA’s Research Prototype of 4D-ASAS En-Route Toolset Attributes Working software prototype w/ ARINC 429 data-bus & 702a FMS integration CD&R alerting is RTCA SC186 ACM-WG compliant Simultaneously meets traffic, airspace, user, and flow management constraints (RTA) Performs trajectory optimization as part of conflict resolution Works within and ‘across’ normal autoflight modes, and within aircraft performance limits Command conflicts Planning conflicts Provisional (FMS/MCP) conflicts Blunder protection and collision data Ownship intent Conflict alerts and information Maneuver restriction information Conflict resolution and trajectory planning Intent-based conflict detection State-based conflict detection Priority rules ATC flow management constraints and airspace constraints AOP Traffic intent Ownship state Traffic state Crew inputs

6 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

7 Pilot-Only Simulation Experiments: Sample Results Aircraft B Aircraft A SUA Crossing Assignment RTA <30 seconds Altitude < 500 ft Position < 2.5 nm Identical crossing assignments Second generation conflict Second generation conflict Planned conflict Over-Constrained Trajectories Conflict Propagation 0% 20% 40% 60% 80% 100% Left aircraft Constraint Conformance missed multiple missed one met all Right aircraft No priority rulesWith priority rules Left aircraft Right aircraft Goal Result: Better predictability Resolution Method Tactical: open loop Strategic: closed loop Modified: pilot override No Events 59 data runs Resolution method Result: Domino effect prevented

8 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. T0: ≈ current monitor alert parameter T1: approximate threshold above which managed only operations will definitely fail (determined by Ames study) Only overflights were increased (arrivals held constant) Autonomous Managed T1 L2 L3 L1 T0 C1C2C3C4 4 test conditions 3 traffic levels 22 commercial airline pilots (20 single pilots + 2 pilot crew in high fidelity simulator) 5 professional air traffic controllers (1 per sector + 1 tracker)

9 Langley Aircraft and Ames Controller Sample Results Pilots mainly able to meet constraints Some pilot entry error (RTA into FMS) No apparent performance degradation as traffic level increased Increasing Traffic Meter fix conformance for arrivals Lower workload for all mixed conditions Traffic levels at C3 and C4 not considered manageable if all aircraft IFR Controller workload assessment Low High

10 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 uncertaintiesFlow-constrained descents Convective weather interaction Failure modes Traffic complexity management Complex AFR/IFR interactions

Dr. Bryan Barmore NASA Langley Research Center A Terminal Arrival 4D-ASAS Concept Airborne Precision Spacing

12 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

13 APS Flight Deck Automation Computes relative ETA at threshold Provides speed guidance to achieve desired relative ETA Safe merging is a consequence of beginning spacing operations early Spacing interval can be customized pair-wise to account for wake vortex hazard and other constraints Adjusts for dissimilar final approach speeds Corrects speed if necessary to prevent separation violations Gain scheduling to enhance stability of a aircraft stream Respects aircraft configuration limits for speed changes Ownship: time to go = 23:15 Lead: time to go = 22:15 30 seconds early at threshold  Slow down 5 knots Target: 90 secs

14 Human-in-the-Loop Evaluation of APS Chicago O’Hare Flight 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 minute flight times Medium fidelity simulation results

15 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

16 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

17 Preliminary Merging and Spacing Simulation Results Separation at merge point 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

18 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

19 Thanks for your attention. (Back-up charts follow)

20 En-Route Safety Impact Assessment Study performed by Volpe National Transportation Systems Center, Oct –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

21 L2 alert (conflict alert) L3 alert (NMAC alert) Display filtering Conflict prevention Flexibility preservation L1 alert (low level alert) Additional Protective Factors Long look-ahead time horizon On-condition intent-change broadcast Intent-based automated conflict detection Alert-based procedures Rapid-update state surveillance Human/automation redundancy L0 alert (traffic point out) X X Safety Design AOP’s Layered Approach to Distributed Separation Assurance Level 1 (L1) alert (low level alert) L2 alert (conflict alert) L3 alert (NMAC alert) Continuous surveillance Right-of-way rules Strategic & tactical CR ACAS Maneuver restriction alerting Protection layers Implicit coordination Nearby aircraft Pre-alert

22 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?