Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project

(1)

Unmanned Aircraft Systems (UAS)

Integration in the National Airspace

System (NAS) Project

Low Size, Weight and Power (SWaP) HITL

Outbrief to SC-228 WG1

UAS INTEGRATION IN THE NAS

March 5 2019

Presented by: Kevin J. Monk

Human Systems Integration

(2)

•

Fast time simulations have narrowed down potential low SWaP

DWC definitions & examined the effect of detection range

– Reduced DWC definitions for non-cooperatives

– Below 3.5nm detection range, Corrective and Warning alert durations begin to drop below Phase 1 requirements

•

Objective: Apply Phase 1 DAA alerting to non-cooperatives

with Low SWaP detection range and DWC definitions

– Characterize pilot performance when provided with similar alerting time to Phase 1 but detection range of 3.5nm

• Compare DWC candidates 1 & 2 from fast time study

– Include wide range of closure rates

– Determine if changes to existing requirements are necessary

(3)

•

Independent Variables

– DWC definition (within-subjects)

• DWC1 (“tau”) = 2000ft HMD, 450ft ZTHR, 15s modTau

• DWC2 (“disc”) = 2200ft HorzDist, 450ft ZTHR, no modTau

– Ownship speed (between-subjects)

• Slow (60kts)

• Fast (100kts)

•

Embedded Variable

(within-trial)

– Conflict type

• Closure rate (fast vs. slow)

– Intruder speed

– Approach angle

• Single vs Multi-threat encounter

Experimental Design

(4)

•

Participants

– 12 active-duty UAS pilots

• Average age: 36.67 years

• Unmanned flight experience: 1,336 hours avg.

• Manned flight experience: 1,731 hours avg.

•

Four experimental trials

(45 minutes each)

– Two pre-filed mission routes

• Fire Line (PT6) and Long Racetrack (FT6 Full Mission)

– Oakland Center (Class E)

•

Ownship: Generic RQ-7 Shadow model

– Mission altitude: 8,000ft MSL

– Maneuverability

• Cruise spd: 60 or 100 KTAS

• Turn rate: 7deg/sec

• Climb/descent rate: 500 ft/min

– Surveillance

• ADS-B In (cooperative)

– Detection range: 20nm

• Low SWaP RADAR (non-coop)

– Limited detection range: 3.5nm

– +/- 110deg azimuth

– +/- 15deg elevation

(5)

•

Primary Pilot Task

– Remain DAA well clear from other aircraft

• 6 scripted DAA conflicts per trial

– 5 single-threat non-coop intruders

» Varying speeds & approach angles

» Includes 1 “Blunder” (Warning at First Alert)

– 1 cooperative intruder (Phase 1 criteria)

» Racetrack: Single-threat, Crossing

» Fire Line: Multi-threat with secondary non-coop intruder

Scenario Design

5 Encounter Label Intruder Speed Approach Angle Proportion Fast Head on 170kts 0 17% Slow Head on 100kts 0 17% Fast Crossing 170kts +/- 90 17% Slow Crossing 100kts +/- 90 17% BLUNDER 100kts 0-90 17% Cooperative 200kts +/- 45 8% Multi-threat

(Fire Line only)

200kts (Coop) +/- 45

8% 100kts (non-coop) 0

25s-to-LoDWC -->

(6)

Icon Alert Level Expected Pilot Response

Time to Loss of DAA Well Clear

Aural Alert Verbiage

4 DAA Warning

Alert Maneuver immediately 30 sec

“Traffic, Maneuver

Now” x2 Corrective DAA

Alert

Maneuver following ATC

approval 60 sec “Traffic, Avoid”

Preventive DAA Alert

Monitor traffic; maneuver not currently

required

N/A “Traffic, Monitor”

Guidance Traffic

Alert No maneuver required N/A N/A

Remaining

Traffic No maneuver required N/A N/A

(7)

•

Research Question

– Is pilot performance with a low SWaP sensor comparable to performance with the Phase 1 RADAR?

– Are changes to the Phase 1 DAA alerting and guidance requirements necessary to accommodate low SWaP sensors?

•

Expected Outcome

– Empirical data to help verify low SWaP sensor requirements and their interactions with DAA alerting, guidance, and display requirements

– Both DWC candidates expected to produce pilot response times and LoDWC rates similar to Phase 1

• Reduced hazard zones may preserve enough alerting time to maneuver safely

– DWC1 (“tau”) should yield greater horizontal separation overall

– DWC2 (“disc”) should allow for more time to maneuver before LoDWC

Hypotheses

(8)

(9)

•

Tau candidate

– More susceptible to short Corrective alert durations

• Especially with Fast Ownship

– Fast Head On: Warning at First Alert (28s)

– Avg. corrective duration overall: 17s

•

Disc candidate

– Over 15 seconds of Corrective alerting time for most encounters

• Exception: Fast Head On

– Avg. corrective duration overall: 23s

Alerting Performance - Unmitigated

9 14 0 30 13 23 9 30 22 0 15 30

Fast Crossing Fast Head On Slow Crossing Slow Head On

C or rect iv e D u ra tion (s ec on d s) Intruder Characteristics

Corrective Alert Duration (Ownship 100ktas)

Tau Disc 19 5 30 27 28 15 30 30 0 15 30

Fast Crossing Fast Head On Slow Crossing Slow Head On

C or rect iv e D u ra tion (s ec on d s) Intruder Characteristics

Corrective Alert Duration (Ownship 60ktas)

Tau Disc

(10)

*Filter Criteria: 184 single-threat, non-blunder, non-coop encounters

Alerting Performance - Mitigated

78 94 12 0 20 40 60 80 100 Tau Disc # of Aler ts DWC Candidate

# of DAA Alerts (at First Alert)

Corrective First Warning First

•

Tau candidate - twice as many Warnings overall relative to Disc

• First appeared as Warning in fastest closure rate encounter

• Correctives also progressed to Warning much more often

– 47% vs. 26% 78 94 49 24 0 25 50 75 100 Tau Disc # of Aler ts DWC Candidate

# of DAA Alerts (Total)

Corrective Warning

(11)

MEASURED RESPONSE

&

ATC COORDINATION

(12)

•

No differential effect of DWC candidate on Aircraft RTs overall

– Nearly identical responses to Correctives & Warnings

•

Aircraft RTs were faster compared to Phase 1 findings

– Uploaded resolutions with a higher sense of urgency

• Initiated edits 3 sec sooner; did not always wait for ATC response

– For all maneuvers against caution-level threats,

• 86% - Notified ATC before upload

• 60% - Waited for ATC approval

– Slightly more often with Disc candidate ➘

DWC Candidate

0.53 0.63 0.86 0.0 0.2 0.4 0.6 0.8 1.0 Tau Disc PT6 P ro p o rt io n w / A p p ro val DWC Definition

Proportion of Maneuvers with ATC Approval (Correctives) 12.36 12.73 18.05 7.00 _6.62 8.13 0 4 8 12 16 20 Tau Disc PT6 Air cr af t R T (s ec on d s) Aircraft RT (single-threat)

Corrective at First Alert Warning at First Alert

(13)

•

Pilots responded equally to threats of both equipage types

– Treated cooperative targets with same urgency as non-coops

• 85% of intruders were non-cooperative

• Developed consistent avoidance strategy, applied to all encounter types

– Limited almost exclusively to lateral maneuvers

– ATC Notification times comparable to findings w/ Phase 1 RADAR (8nm)

• PT6: more even distribution of coop (62%) vs. non-coop traffic (38%)

Intruder Equipage

13 13.08 19.25 12.48 17.08 0 2 4 6 8 10 12 14 16 18 20 22 Low SWaP PT6 Air cr af t R T (s ec on d s) Study

Aircraft RT (Corrective Only)

ADSB RADAR

(14)

(15)

•

3 total LoDWC out of 289 encounters =

1%

– Zero NMACs, nearly identical to Phase 1 performance

– All from 1 pilot, all short-duration Corrective alerts

• Corrective alert duration: 9-14s

• 2 due to ineffective altitude maneuvers

Losses of DAA Well Clear

15 0.014 0.007 0.013 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Tau Disc PT6 Pr op or tion of LoDW C DWC Criteria LoDWC Proportion

DWC sLoWC% Duration Cause Encounter

Tau 1.47 6s Early Return to Course (361ft. vertSep) Slow Head On (secondary threat) 11.27 16s Ineffective maneuver (altitude only) Fast Crossing

Disc 30.63 9s Ineffective maneuver (altitude only)

Fast Head On

(16)

(17)

•

Two-thirds of pilots indicated that 3.5nm – or more – would be

their minimum acceptable surveillance range

– One third would find 2.5-3nm acceptable

– Contingent factors:

• Higher mission task workload

– Secondary tasks were minimal distraction; stayed ready

• Emergencies – turning off course may not be feasible (low fuel, need to land)

• Vigilance decrements during long duty cycles

• Congested communication frequency

• Latency

• “Expect faster response with GCS input controls”

Subjective Feedback

17 4 4 4 0 2 4 6 8 10 12 <3.5nm 3.5nm 5 - 8nm # o f R e sp o n se s Reported Value

(18)

CONCLUSIONS

&

(19)

•

Objective metrics clearly indicate that pilots can maintain DWC

with either DWC candidate at 3.5NM detection range

– Tau ➝ less Corrective alert time + more Warning alerts

– Full ATC coordination not always viable

– Disc ➝ longer Corrective times (~6sec) + earlier onset of Recovery bands

– Quick response times limited LoDWC occurrences to 1 pilot

•

Pilot response times against Corrective alerts ~5sec faster than

observed in Phase 1; no difference observed for Warning alerts

– Closer proximity at first alert

• 60% were active DAA alerts at first appearance

• Frequent short-duration Corrective alerts

– Pilots adopted a global strategy of initiating edits immediately in response to all Correctives (including against cooperative intruders)

• Aircraft performance (faster turn, slower climb) limited maneuver options

•

Potential challenges to reducing detection ranges below 3.5nm

– Pilot acceptability

– May not be able to retain Corrective alerting (especially w/ Tau)

Implications

(20)

kevin.j.monk@nasa.gov

conrad.rorie@nasa.gov