Characteristics of a Well Clear Definition and Alerting Criteria for Encounters between UAS and Manned Aircraft in Class E Airspace!

Transcription

1 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

2 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

3 14CFR Part 91, Background vigilance shall be maintained by each person opera.ng an aircraj so as to see and avoid other aircraj pilot shall give way to that aircraj and may not pass over, under, or ahead of it unless well clear. UAS operaang under IFR Aircra> OperaAng under Instrument Flight Rules (IFR) Collision Avoidance Air Traffic Control Aircra> OperaAng under Visual Flight Rules without a Transponder (Non- cooperaave VFR) Aircra> OperaAng under Visual Flight Rules with a Transponder (CooperaAve VFR) 3

4 Background: Detect and Avoid Analysis 2: Aler.ng the UAS Operator Collision Avoidance Analysis 1: Loss of Well Clear Collision Avoidance Manned AviaAon Unmanned AviaAon See and Avoid Traffic Collision Avoidance System (TCAS) Detect and Avoid Collision Avoidance Func.on (TCAS/ACAS/etc.) 4

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 Encounter Characteris.cs at the Loss of Well Clear (LoWC) 5

6 Unmitigated Encounter Rate Evaluation CapabiliAes US NaAonal Airspace System SimulaAon UAS Models UAS Mission Profiles Metrics Loss of Well Clear VFR Traffic from Air Defense Radar Data Self SeparaAon Conflict AlerAng Airspace Concept EvaluaAon System (ACES) Analysis Losses of Well Clear per UAS Flight Hour Results AlAtude 6

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 7

8 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 aircraj 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 8

9 Analysis 1: Characterizing Encounters at Well Clear Boundaries Analysis 1: Loss of Well Clear Collision Avoidance 9

10 Rate of Losses of Well Clear by Definition Losses of Well Clear Per UAS Flight Hour D1.1 D1.2 D1.3 τ* mod τ* vert ZTHR HMD [s] [s] [J] [J] D D D January April July October UAS Community Proposed Defini>ons 10

11 Relative Heading and Distance at LoWC nmi nmi nmi D D D τ* mod τ* vert ZTHR HMD [s] [s] [J] [J] D D D % % 80% 60% 11

12 Range Rate vs. Separation at LoWC (Horizontal) Horizontal Range Rate [knots] 200 Horizontal Range Rate [kts] LoWC on Back End of Threat Boundary Threat Boundary ViolaAon (4000 >) LoWC at Modified Tau Threshold (35 seconds) High Range Rate LOWC Density Horizontal Separation [nmi] Horizontal SeparaAon [nmi] τ* mod τ* vert ZTHR HMD [s] [s] [J] [J] D

13 Results indicate: Concluding Remarks An unmi.gated loss of well clear occurs approximately once every 40 flight hours. Head- on encounters occur at further surveillance ranges then over- taking encounters Most losses of well clear occur within 1-3 nau.cal miles and less than 200 knots closure rates Recommenda.ons: A.me and distance- based well clear defini.on is mo.vated by: maneuvering intruders high closure rate intruders. A minimum 4-5 nmi surveillance range is recommended to account for missed alerts. 13

14 Additional Remarks: Analysis 2 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 14

15 Questions 15