National Aeronautics and Space Administration Characteristics of a Well Clear Definition and Alerting Criteria for Encounters between UAS and Manned Aircraft in Class E Airspace! NASA Ames Research Center Marcus Johnson Confesor Santiago Eric Mueller! 1
Research and Mo.va.on Analysis Overview and Defini.ons Simula.on Setup Traffic Scenarios UAS Missions Fast- Time Simula.on Study Results Outline Analysis 1: Characterizing Encounters at Well Clear Boundary Analysis 2: Evalua.ng Aler.ng Criteria Conclusions 2
14CFR Part 91, 91.113 Background vigilance shall be maintained by each person opera.ng an aircran so as to see and avoid other aircran pilot shall give way to that aircran and may not pass over, under, or ahead of it unless well clear. UAS opera6ng under IFR Aircra3 Opera6ng under Instrument Flight Rules (IFR) Collision Avoidance Air Traffic Control Aircra3 Opera6ng under Visual Flight Rules without a Transponder (Non- coopera6ve VFR) Aircra3 Opera6ng under Visual Flight Rules with a Transponder (Coopera6ve VFR) 3
Background: Detect and Avoid Analysis 2: Aler.ng the UAS Operator Collision Avoidance Analysis 1: Loss of Well Clear Collision Avoidance Manned Avia6on Unmanned Avia6on See and Avoid Traffic Collision Avoidance System (TCAS) Detect and Avoid Collision Avoidance Func.on (TCAS/ACAS/etc.) 4
Motivation Special CommiJee 228 Minimum Opera6onal Performance Standards for Unmanned Systems Surveillance and Aler.ng Requirements Opera.onal Environment Safety Requirements 5
Analysis Overview Analysis 1: Characterizing encounters at well clear boundaries. Objec.ve: Inves.gate implica.ons of using Well Clear Defini.ons proposed from the UAS community in terms of surveillance requirements and safety. Metrics: Rate of Losses of Well Clear per UAS Flight Hour Rela.ve State informa.on at the Loss of Well Clear (LoWC) Analysis 2: Evalua6ng the aler6ng criteria. Objec.ve: Inves.gate implica.ons of an aler.ng scheme as suggested from the UAS community in terms of surveillance requirements and safety. Metrics: Rate of Alerts per Flight Hour Percentage of Nuisance Alerts Rela.ve State Informa.on at First Alert Time to Loss of Well Clear 6
Unmitigated Encounter Rate Evaluation Capabili6es US Na6onal Airspace Simula6on UAS Models UAS Mission Profiles Metrics Loss of Well Clear VFR Traffic from Air Defense Radar Data Self Separa6on Conflict Aler6ng Airspace Concept Evalua6on System (ACES) Analysis Losses of Well Clear per UAS Flight Hour Results Al6tude 7
Loss of Well Clear DMOD R xy t CPA HMD 0 apple mod apple mod R xy (t CPA ) apple HMD ZTHR mod vert h Note: DMOD value = HMD value 0 apple vert apple vert OR h applezthr Loss of Well Clear mod = R2 xy DMOD 2 t CPA Time at Closest vert = Ṙ xy R xy Point of Approach h h 8
Alerting Criteria DMOD R xy 0 apple mod apple SST mod t CPA Self- Separa.on Threshold (SST) HMD R xy (t CPA ) apple HMD h applezthr mod = R2 xy DMOD 2 Ṙ xy R xy t CPA ZTHR h Time at Closest Point of Approach Self- Separa6on Conflict Alert 9
UAS Missions Overview Air Quality Monitoring UAS Size Overall Mission Characteris6cs Cargo Transport Flight Dura6on Aerosonde Global Hawk Flood Mapping Atmospheric Sampling Wildfire Detec6on and Reconnaissance On- Demand Air Taxi 1 Hour 20 Hours Flights Per Day 20 8,000 Cruise Al6tude 2,000 N 31,000 N Flight PaJern Grid Pahern Circular Loitering Point- to- point KXYZ 10
Simulation Configuration There are 24 different simula.on runs 1 simula.on run is a single day in the US na.onal airspace system (NAS) Each simula.on had UAS: 9 Different Proposed Missions Total of 18,000 UAS flights in data set (~26,000 flight hours) Variety of aircran performance, mission profiles, geographic areas of opera.on Traffic: Coopera.ve VFR Traffic (secondary radar returns) Derived from 84 th squadron air defense radar data Varying volume of traffic (20-28k flights) Days are spread over 4 seasons in 2012 (24 days total) No Separa.on mi.ga.on Metrics only collected for UAS vs. VFR conflicts No Detect and Avoid System was present 11
Analysis 1: Characterizing Encounters at Well Clear Boundaries Analysis 1: Loss of Well Clear Collision Avoidance 12
Rate of Losses of Well Clear by Month Losses of Well Clear Per UAS Flight Hour 0.04 0.03 0.02 0.01 D1.1 D1.2 D1.3 τ* mod τ* vert ZTHR HMD [s] [s] [N] [N] D1.1 30 20 475 6000 D1.2 35 0 700 4000 0 January April July October SARP Proposed Defini<ons D1.3 35 0 450 4000 RTCA Proposed Defini<on 13
Relative Heading and Distance at LoWC 180 180 180 150 210 150 210 150 210 120 240 120 240 120 240 90 5 nmi 2.5 270 90 5 nmi 2.5 270 90 5 nmi 2.5 270 60 300 60 300 60 300 30 0 D1.1 330 30 0 D1.2 330 30 0 D1.3 330 τ* mod τ* vert ZTHR HMD [s] [s] [N] [N] D1.1 30 20 475 6000 D1.2 35 0 700 4000 D1.3 35 0 450 4000 99% 240 90% 80% 60% 14
Analysis 2: Evaluating the Alerting Criteria Analysis 2: Aler.ng the UAS Operator Collision Avoidance 15
Rate of Self Separation Alerts Alerts per Flight Hour SST HMD ZTHR [s] [ft] [ft] D2.1 90 4000 450 D2.2 90 4000 700 D2.3 110 4000 700 D2.4 70 4000 700 D2.5 90 6000 700 D2.6 90 6000 900 Note: Defini<ons Based on D1.3 (RTCA Proposed Well Clear Defini<on) 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 D2.1 D2.2 D2.3 D2.4 D2.5 D2.6 16
Percentage of Nuisance Alerts Percentage of Nuisance Alerts SST HMD ZTHR [s] [ft] [ft] D2.1 90 4000 450 D2.2 90 4000 700 D2.3 110 4000 700 D2.4 70 4000 700 D2.5 90 6000 700 D2.6 90 6000 900 70 60 50 40 30 20 10 0 D2.1 D2.2 D2.3 D2.4 D2.5 D2.6 17
Time to LoWC at First Self Separation Alert Median µ Mean 25% 75% 9% 91% Time to LoWC [sec] 80 70 SST HMD ZTHR [s] [ft] [ft] D2.1 90 4000 450 D2.2 90 4000 700 D2.3 110 4000 700 D2.4 70 4000 700 D2.5 90 6000 700 D2.6 90 6000 900 Note: D1.3 is used to define a LoWC (RTCA Proposed Well Clear Defini<on) 60 50 40 30 20 10 0 D2.1 D2.2 D2.3 D2.4 D2.5 D2.6 18
Relative Heading and Distance at First Self Separation Alert D2.1 D2.2 D2.3 D2.4 D2.5 D2.6 SST HMD ZTHR [s] [ft] [ft] D2.1 90 4000 450 D2.2 90 4000 700 D2.3 110 4000 700 D2.4 70 4000 700 D2.5 90 6000 700 D2.6 90 6000 900 120 90 10 5 270 15 nmi 60 150 30 Note: All contours represent max boundary of 99% of data 180 0 210 330 240 300 19
Conclusions and Recommendations Surveillance and Aler.ng Guidelines: DAA system would want a surveillance range of 4-5 nmi Using the proposed aler.ng criteria the surveillance range would nominally need to be 10 nmi to alert the UAS operator to take ac.on There is a trade- off between.me to loss of well clear and percentage of nuisance alerts The larger the aler.ng volume è More.me before loss of well clear and larger percentage of nuisance alerts. Recommenda.ons: Consider buffers for aler.ng criteria Include ownship intent in aler.ng criteria Consider mul.ple layers of aler.ng 20
Questions 21