NASA/FAA/RLD/NLR Free Flight study

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-1A

• “Free Flight with Airborne Separationwill result in an uncontrolled, dangerous jungle

without a firm central controlling elementsuch as ATC.”

• “Pilots haven’t got the time, the training nor the mental resources available to

function as ATC on top offlying the aircraft.”



CXXX-2A

NASA/FAA/RLD/NLRFree Flight study

Jacco Hoekstra ([email protected])

Ronald van Gent

Rob Ruigrok



CXXX-3A

Free Flight goals

Reduce Costs via user preferred routing– Horizontally

• direct to destination• optimum speed

– Vertically • optimum level• cruise climb

More capacity



CXXX-4A

Operational concept

No ATC – Probe the limits for HF problems

All aircraft fully equipped– Linked via e.g. ADS-B– EFIS-CDTI

Full user preferred routing– Direct routing– Optimal cruise altitude



CXXX-5A

1997: Three sub-studies: CONCEPTUAL DESIGN

Tool: Traffic Manager: Off-line simulations– Find a suitable base-line concept

SAFETY ANALYSISTool: TOPAZ (Traffic Organization and Perturbation AnalyZer)– Compare safety of Airborne Separation with

safety ATC

MAN-IN-THE-LOOP EXPERIMENT phase ITool: Research Flight Simulator– Validation of concept with Man-in-the-Loop– Man Machine Interface Validation



CXXX-6A

1998: Four sub-studies: CONFLICT GEOMETRY STUDY

Tool: Traffic Manager: Off-line simulations– Check critical geometries: wall, etc.

AVIONICS STUDYLiterature survey– Check requirements for RNP, ADS-B etc.

COST-BENEFITS & PERFORMANCETool: Traffic Manager: Off-line simulations– Costs of conflict resolution

MAN-IN-THE-LOOP EXPERIMENT phase IITool: Research Flight Simulator– Validation of PredASAS & mixed equipage



CXXX-7A

1999: Three activities:

DISSEMINATIONConferences, Web site, Contract report, RTCA, ICAO– Explain results obtained so far

DATA ANALYSIS phase II trials- Analysing data generated in phase II trials

DEVELOPMENT HUMAN INTERACTION EXPTool: Traffic Manager, Freesim & internet– Effect of competition



CXXX-8A

2000+: Current and future activities

HUMAN INTERACTION EXPERIMENTTraffic Manager, FreeSim, internet- High number of participants, humans vs models, competition

PHASE III FLIGHT SIMULATOR TRIALSNLR simulator, NASA Langley Simulations, HIE cfg(?)- How low can you go? From cruise to final incl. SUA, weather, RTA

Continue dissemination effortsWeb site, symposia, conferences, RTCA, SAE, (IF)ALPA



CXXX-9A

Traffic & Experiment Manager



CXXX-10A

Resolution advisoriesSeveral concepts studied:– Altitude step– Cross product of speed vectors– Extended VFR rules (not implemented)– Variations of TCAS manoeuvres – Voltage potential

Co-operative manoeuvring vs. priority

Minimal bandwidth/HF: no intent in Conflict Detection

Result Traffic Manager simulations



CXXX-11A

Conflict Detection & Resolution

Intruder’s protected

zone

Heading distance

Speed change

Avoidance vector

Minimum distance

Ownship

Intruder



CXXX-12A

Complex Conflict geometries

‘Wall’ scenarios, ‘super conflict’ (n = 4,8,10,12,16) and ‘crossing the street’



CXXX-13A

Man-in-the-loop Simulation Configuration

AIRSIM

RFS

TEM



CXXX-14A

Traffic Symbol added to ND Symbology on Navigation display based on data

available via ADS-B

Track indicated with arrow shaped symbol instead of track line to avoid clutter

Label text selectable with de-clutter switches

Call sign added to label of traffic symbol for inter-trafficand crew communication



CXXX-15A

Conflict Detection & Resolution

Symbology based on resolution algorithm

Provides insight into resolution

Colour indicates urgency:Amber = 3 - 5 minRed = 0 - 3 min(time to loss of separation)



CXXX-16A

Navigation Display



CXXX-17A

Man-in-the-Loop experimentHypotheses

First explorative HF experiment, so probably using ‘simple’ Mk 1 system would yield:

Less than acceptable

Subjectively less safe

More workload

Result: MMI problem areas



CXXX-18A

Man-in-the-Loop experimentResults - Acceptability

0

10

20

30

40

50

60

70

80

90

100

su

bje

cti

ve

rati

ng

acce

pta

bilty

in

pe

rce

nta

ge

s

single

double

triple



CXXX-19A

Man-in-the-Loop experimentResults- Subjective Safety

0

10

20

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40

50

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ATC muchsafer

ATC safer Same FF safer FF muchsafer

Su

bje

ctiv

e r

atin

gs

saf

ety

in p

erc

en

tag

es

set 1

set2

set3



CXXX-20A

Man-in-the-Loop experimentResults

Subjective Workload

33.85 35.4228.76

0

20

40

60

80

100

120

140

first second third



CXXX-21A

Task comparison Controlled vs. Free Flight

Fly

Navigate

Communicate with ATC

Fly

Navigate

Separation

Controlled Flight Free Flight



CXXX-22A

Predictive ASAS

• Calculates which track, vertical speed and speed selections will result in a conflict within the look ahead time

• Predicts a conflict by the red/amber zone moving to the actual values

• Indications do not require pilot actions



CXXX-23A

Predictive ASAS

Don’t go indications:• Track• Vertical speed• Speed



CXXX-24A

Preliminary conclusions PASAS

With predictive ASAS even conflict alerts could be avoided

Enhances situational awareness

Might provide solution without use of intent information for Free Flight!



CXXX-25A

Mixed equipage ATM concepts

Flight Level division:Above FF level only equipped aircraft

Protected Airways:Controlled aircraft should stay on airways and have right of way

Fully Mixed:ATC uses longer ‘look ahead’ time, so equipped aircraft have effectively ‘right of way’



CXXX-26A

1998 NASA / FAA / RLD Results: Workload Airborne

Subjective: Objective:

Pilot objective workloadTwo-way interaction of ATC condition and

equipage (p<0.044)

-1-0.8-0.6-0.4-0.2

00.20.40.60.8

1

ProtectedAirways

Full Mix Flight Level

ATC condition

Sca

n r

and

om

nes

s (Z

sco

re)

Equipage 25% Equipage 75%

Pilot subjective workloadTwo-way interaction of ATC condition

and equipage (p<0.16)

-1-0.8-0.6-0.4-0.2

00.20.40.60.8

1

ProtectedAirways

Full Mix Flight Level

ATC condition

RS

ME

(Z

sco

re)

Equipage 25% Equipage 75%



CXXX-27A

1998 NASA / FAA / RLD Results: Workload Ground

F(2,8)= 9.7, P< .008



CXXX-28A

1998 Man-in-the-loop Conclusions

The future ATM design has to be chosen very carefully:– Full Mixed ATM condition is best from the pilot’s perspective– Protected Airways ATM condition is sensitive to equipage

level (transition in time)– Flight Level ATC condition is most optimal from Air Traffic

Controller’s perspective (Hilburn, Pekela)

The flight deck crew was able to handle higher traffic densities than the ground controller



CXXX-29A

Current men-in-the-loop experiment:human interaction experiment

Logging into Traffic Manager via internet using downloadable FreeSim flight simulation program

Goal: Test effect of• humans vs models• competition



CXXX-30A

Airport on FF perspective: bad news(?)

Dramatic airspace capacity increase in FF airspace (en-route) => airports will be bottleneck (again)

European ATC delays (Eurocontrol)

0

20

40

60

80

100

120

140

160

Year 98 Year 99

Norm 98 (%)Other

En-route



CXXX-31A

Airport perspective on FF: good news

ASAS equipment (especially traffic display) could facilitate more efficient use under IMC of:

– airspace (curved, merging, station keeping)– runways (concurrent use of parallel and crossing runways)– taxiways (showing other a/c and ground vehicles)

=> potential to increase sustained capacity



CXXX-32A

More information

Web site: http://www.nlr.nl/public/hosted-sites/freeflight

Comprehensive report on overall studies 1997-1999Will soon be published. Check web site for downloads!

Demo sessions of human interaction experiment configuration will be announced on the website

Documents

NASA/FAA/RLD/NLR Free Flight study