National Aeronautics and Space Administration Next Generation Air Transportation System Airspace Project NASA ASAS Activities: Decision Support for Airborne Trajectory Management & Self-Separation Robert A. Vivona AOP Lead Engineer L-3 Communications Billerica, MA Greetings. Thanks and acknowledgements of authors. This presentation is about a recent study on pilot response delay done at NASA as part of the NextGen airspace project. ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Presentation Overview Background Airborne trajectory management Autonomous Operations Planner (AOP) Provided ASAS functions System interface Capabilities AOP Experimental Performance Concluding Remarks

Background: Airborne Trajectory Management Concept Trajectory-oriented operations En route & transition to terminal Aircraft self-optimization Mixed environment Self-separating & ground managed aircraft Self-separating aircraft: Flight-deck decision support equipped Autonomous Operations Planner “Autonomous Flight Rules” Self-separate (traffic & area hazards) Conform to flow constraints Don’t generate conflicts within 5 mins Broadcast state & intent data FMS & air/ground data link equipped Ground managed aircraft Similar to today’s operations Broadcast state (and intent) data Terminal Airspace (Merging & Spacing) Q En Route Airspace Ground managed Self-separating ATSP Responsibilities Manage airspace resources Generate flow constraints Datalink to autonomous aircraft Control ground managed aircraft ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Autonomous Operations Planner (AOP) Purpose: enable trajectory management Conformance to constraints Separation from traffic aircraft Avoidance of special use airspace Minimum penetration of weather hazards Conformance to time-based flow constraints Path optimization Supports navigation & guidance decisions Concept of use Detects & alerts need to modify trajectory Supports trajectory modifications: Strategic & tactical maneuver alternatives “What-if” maneuver analysis Generates user-optimal paths Automatically adapts to flight-crew chosen guidance mode Tactical Maneuver Restriction Region Area of Conflict Along Current FMS Route Resolution Maneuver Uploaded to FMS as Mod Route Conflict Aircraft Navigation Display ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

AOP: Provided ASAS Functions AOP Approach Traffic Data Identify Reference Aircraft Primary Function: Uses ADS-B and TIS-B information to track and predict traffic aircraft behavior. Track Reference Aircraft Provide Reference Aircraft’s Trajectory Assessing Initiation Criteria Not supported (though could be). Not yet required for current research efforts. Assessing Continuation Criteria Assessing Termination Criteria Merge Compute Maneuvers to Merge Not required. Separate system (PDS) at Langley provides merging & spacing capability. Compute Merge Location Follow Compute Dependent Following Trajectory Manage Interval Compute Speeds to Achieve and Maintain Interval Monitor Interval Conformance Separation Maintenance Monitor Maintenance of Separation Secondary Function: Uses state-based CD&R for blunder protection. Compute Guidance to Maintain Separation Conflict Detection Probe Trajectory For Conflicts Primary Function: Uses both intent-based and state-based approaches. Alert Crew to Conflicts Conflict Resolution Compute Vertical Maneuvers to Provide Separation Primary Function: Uses both strategic and tactical approaches. Compute Lateral Maneuvers to Provide Separation Compute User-Preferred Trajectory to Provide Separation Trajectory Optimization Compute Traffic-Constrained User-Preferred Trajectory Primary Function: Provided by provisional trajectory analysis. Compute Aircraft Performance Compute Maneuvering Flexibility Primary Function: Looks within and outside resolution horizon. *Source: FAA/Eurocontrol Cooperative R&D AP23 ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

AOP: System Interface Inputs: Flight Management Guidance settings Traffic data Weather data AOP MCDU data Flight Management System (FMS) Mode Control Panel (MCP) Flight Control Computer (FCC) Other Sources: GNSS Clock ADS-B TIS-B FIS-B AOP Inputs Autonomous Operations Planner (AOP) AVIONICS DATA BUS Multi-Function Control & Display Unit (MCDU) Outputs: Conflict alerts FMS route mods MCP setting mods AOP MCDU data AOP Outputs Integrates with Existing Avionics & Displays Navigation Display Primary Flight Display (PFD) ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Maneuver without conflict (conflict prevention) AOP: Capabilities Conflict management Probe multiple maneuvers for situation awareness Conflict detection and resolution details Intent-based and state-based approaches Maneuver without conflict (conflict prevention) Provisional (“what-if”) planning Maneuver restriction bands ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008 7

Conflict Management Approach: Probe all relevant maneuvers (trajectories) requiring evaluation by flight crew Display all conflicts to provide complete situation awareness Provide resolution capabilities for each maneuver AOP can simultaneously predict/evaluate multiple ownship maneuvers Maintaining current guidance (Commanded Prediction) Evaluate impact of current guidance settings “What happens if I don’t change the guidance settings?” Reconnecting to strategic route (Planning Prediction) Advise & evaluate maneuver to re-establish FMS active route “How do I get back to my long-range plan?” Stop maneuvering (State-vector projection) Evaluate impact of maintaining current state “What happens if I stop or don’t start/continue maneuvering?” (e.g., blunder) Not all maneuvers always relevant ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management Commanded Prediction FMS Predicted Top-of-Descent State vector projection VNAV PATH LNAV/VNAV VNAV ALT Commanded prediction MCP altitude limit Planning prediction VNAV PATH Active Route Altitude Constraint Primary CD Alerting Secondary CD Alerting Commanded Prediction Predicts impact of current guidance mode settings Initiates VNAV PATH descent Predicts guidance switch to VNAV ALT at MCP altitude Primary CR impacts active guidance Planning Prediction Predicts impact of most strategic path Predicts VNAV PATH descent Ignores MCP altitude Secondary CR impacts non-active path State vector projection Predicts impact of not initiating descent State projection at cruise altitude Point out / override CD&R ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management Primary conflicts on the commanded prediction Secondary conflicts on planning and blunder (state-vector) predictions LNAV On path TRACK HOLD Off path Within capture TRACK HOLD Off path Beyond capture Commanded Commanded Blunder Protection Commanded Last LOS Planning First LOS ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management: Conflict Detection & Resolution Intent-based conflict detection Trajectory prediction Ownship Traffic Trajectory prediction uncertainty buffers Intent-based conflict resolution Strategic & tactical State-based CD&R ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management: Intent-Based CD 1xN probing of ownship versus all hazards (traffic and area) Probes ownship 4D trajectory against all traffic aircraft 4D trajectories and area hazard geometries Configurable research parameters Required separation zone Independent values for AFR & IFR traffic Look-ahead Typically 10 minutes Uses prediction uncertainty bounds Independent definitions for ownship and traffic different maneuvers (flight modes) Conflict = predicted loss between uncertainty regions ownship traffic ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Intent-Based CD: Trajectory Prediction ADS-B Mode Status Report (MSR) Air Referenced Velocity Report (ARV) Trajectory Change Report (TCR) State Vector Report (SVR) Target State Report (TSR) Ownship Generated from aircraft guidance settings Primarily based on Sensors: initial condition MCP, FMS, FCC, MCDU settings Numerical integration using internal trajectory predictor FMS quality prediction for all guidance modes Trajectory generated for CD application (commanded, etc.) Traffic Generated from ADS-B data Primarily based on: SVR: initial condition TCR: represents predicted trajectory TCP+N approach No numerical integration Exploring using TSR with integration for tactical guidance modes One trajectory per traffic aircraft (used for all CD applications) ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Intent-Based CD: Trajectory Prediction Uncertainty Buffers Vertical Time Altitude Cross-track Cross-track Time 4D “tube” around 4D trajectory Encapsulates prediction uncertainties unique to each segment type Time Lateral path ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management: Intent-Based Conflict Resolution Strategic Develops FMS-compatible routes Uploaded directly into the FMS Crew requested (semi-automatic) Solution: Independent lateral and vertical maneuver options Approach: Resolves all conflicts and constraints, non-cooperative (priority rule-based) Pattern-Based Genetic Algorithm Tactical Develops MCP setting advisories Automatic when FMS decoupled or short time to conflict Independent altitude, vertical rate, heading/track options Resolves all conflicts, non-cooperative (priority rule-based) Sweep until first conflict free setting found ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management: Intent-Based Conflict Resolution Nav Display Primary Flight Display Track Advisory Vertical Rate Altitude Active Route: Magenta Resolution Route: Blue Nav Display Strategic Intent-Based CR Tactical Intent-Based CR ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Conflict Management: State-Based CD&R Independent system from intent-based CD&R Supports Blunder protection Override for short term conflicts Approach Two options NLR (Modified Voltage Potential) Langley (KB3D) Resolution advisories Independent MCP settings track/heading, vertical rate, altitude Automatically displayed when needed Similar characteristics Resolves most immediate conflict Cooperative/Non-cooperative (configurable) Maneuver to increase to minimum separation standard Implicitly coordinated with other traffic maneuvers CD Look-ahead at 5 minutes (configurable) No area hazard detection Does not consider uncertainty Modified Voltage Potential

Maneuvering Without Conflict (Conflict Prevention) Provisional (what-if) planning Non-conflict generated maneuver Probe for conflicts before execution FMS provisional Automatic probe of FMS MOD route MCP provisional Automatic probe of non-active MCP inputs Maneuver restriction (MR) bands Protect against unallowable maneuvers Conflicts generated within 5 mins Bands show unallowable MCP settings Lateral (track/heading) Vertical (vertical rate) Automatically generated for: Non-active MCP setting change Switch to tactical guidance mode FMS Provisional Conflict Manual MOD Route in FMS Lateral MR Band MCP Provisional Conflict Non-active Change in MCP Track Setting (e.g., in LNAV) ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

AOP Experimental Performance Experiment 1: Lateral Only, Random Routes, All Autonomous 10X playback speed Sustained Mean Density1 Sim. Hours Simulated flights Traffic conflicts LOS2 2x 3 10x 3.45 36 881 195 6.11 1527 550 8.61 2195 1018 11.64 3000 1788 15.24 12 1302 963 17.18 1560 1256 Totals 168 10,465 5770 Lateral Strategic CR Only NASA Air Traffic Operations Lab All aircraft co-altitude, circle diameter 160 NM Sustained Mean Density1 17.18 1 Aircraft per 10,000 NM2 2 Loss of separation (5 NM) 3 Ref. sector ZOA31 – median density, 19 Feb 2004 Consiglio, Hoadley, Wing, Baxley: Safety Performance of Airborne Separation - Preliminary Baseline Testing. AIAA-2007-7739. ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

AOP Experimental Performance Experiment 2: Lateral Only, Random Routes, All Autonomous, Pilot Delay Average Density(*) Average Pilot Delays (Seconds) Flight Hours Total Conflicts Total LOS(**) 11.2 5X/3X 3.5 240.73 583 16.3 8X/5X 90.71 316 1 21.4 12X/7X 572.76 2307 2 Totals: 904.20 3206 3 This chart shows the effect of extreme density (~complexity) test conditions with normal pilot delays and all pilots responding on LOS At the highest density level and under the constrained conditions of the experiment scenarios, the resolution function was able to find a strategic (lateral) solution in all but two cases. In fact, out of 2307 conflicts generated in 572 simulated flight hours there were 2 instances where a resolution was not found. The case involved a 4-aircraft conflict in which one of them lost separation with two of the intruders The full implementation of AOP would revert to a tactical resolution algorithm to before three minutes to go. Removing constraints: tactical resolutions vertical degree of freedom to the resolution computation Additional resolution maneuver patterns. Lateral Strategic CR Only (CPA < 0.02 nmi) (*)Relative to mean and peak 1X densities of 1.8 and 3 aircraft, normalized to 10000 nmi2, at the most populated flight level of the median-density sector on 19 Feb 2004. (**) All 3 LOS events were from high-complexity multi-aircraft conflicts. The 2 LOS events at the 21.4 density involved a 4-aircraft conflict in which one aircraft lost separation with two of the intruders. Consiglio, Hoadley, Wing, Baxley, Allen: Impact of Pilot Delay and Non-Responsiveness on the Safety Performance of Airborne Separation. ATIO 2008. ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

AOP Performance: Batch Experiment 2 Experiment 2: Lateral Only, Random Routes, All Autonomous, Pilot Delay Number of intruder aircraft per conflict resolutions. As traffic density increases, so does the number of multi-aircraft conflicts, which reflects increased traffic complexity Understanding the effect of response delay and traffic density: Both graphs correspond to pilot delays of 240 sec. AOP Intent-Based CD&R Studied Under Highly Complex Traffic Scenarios ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Concluding Remarks: Current NASA Efforts SPAS (Safety Performance of Airborne Separation) PI: María Consiglio Studying effects of major error sources (e.g., wind error) on safety performance SPCASO (Safety & Performance Characterization of Airborne Self-Separation Operations) Prediction uncertainty PI: Danette Allen Studying use of trajectory prediction uncertainty bounds to mitigate prediction error Mixed operations PI: David Wing Studying impact of mixed AFR and IFR traffic Investigating approaches to mitigating traffic complexity using AOP ADS-B Performance PI: Will Johnson Studying impacts of ADS-B range, interference and limited intent ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Concluding Remarks: AOP References System Concept Ballin, M.G., Sharma, V., Vivona, R.A., Johnson, E.J., and Ramiscal, E.: “A Flight Deck Decision Support Tool for Autonomous Airborne Operations,” AIAA Guidance, Navigation, and Control Conference, AIAA-2002-4554, August 2002. CD&R Vivona, R., Karr, D., and Roscoe, D., “Pattern-Based Genetic Algorithm for Airborne Conflict Resolution”, AIAA Guidance, Navigation and Control Conference, AIAA-2006-6060, August 2006. Karr, D., and Vivona, R., “Conflict Detection Using Variable Four-Dimensional Uncertainty Bounds to Control Missed Alerts,” AIAA Guidance, Navigation and Control Conference, AIAA-2006-6057, August 2006. Mondoloni, S., Ballin, M., and Palmer, M.: “Airborne Conflict Resolution for Flow-Restricted Transition Airspace,” 3rd AIAA Aviation Technology, Integration and Operations (ATIO) Conference, AIAA-2003-6725, November 2003. Experiments Consiglio, M., Hoadley, S., Wing, D., and Baxley, B., “Safety Performance of Airborne Separation: Preliminary Baseline Testing,” 7th AIAA Aviation Technology, Integration and Operations (ATIO) Conference, AIAA-2007-7739, September 2007. Consiglio, M., Hoadley, S., Wing, D., Baxley, B., and Allen, D., “Impact of Pilot Delay and Non-Responsiveness on the Safety Performance of Airborne Separation,” 8th AIAA Aviation Technology, Integration and Operations (ATIO) Conference, AIAA-2008-8882, September 2008. ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008

Demonstration Demo ~10x traffic density 10x playback speed Long range display No display filtering Lateral Intent-Based CR Navigation Display ASAS TN2.5 Workshop, Rome, Italy, November 13, 2008