World Aviation Congress 1999, 99WAC-111 San Francisco, 19 October 1999

Nationaal Lucht- en RuimtevaartlaboratoriumNational Aerospace Laboratory NLR

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The Transition Towards Free Flight: A Human Factors Evaluation of Mixed Equipage, Integrated Air-Ground, Free Flight ATM Scenarios

World Aviation Congress 1999, 99WAC-111

San Francisco, 19 October 1999

R.C.J. Ruigrok, R.N.H.W. van Gent, J.M. Hoekstra


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Explanation of title The Transition Towards Free Flight:

– in time and in space

A Human Factors Evaluation– objective and subjective measurements

of Mixed Equipage– aircraft with and without ADS-B, CDTI and CD&R

Integrated Air-Ground– air and ground players have a defined role

Free Flight ATM Scenarios– newly defined


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Overview

NLR studies on Free Flight

1997 human-in-the-loop experiment– in summary

1998 human-in-the-loop experiment– in detail

Conclusions and recommendations


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NLR studies on Free FlightOverview

Studies on Airborne Separation Assurance, the flight deck perspective:– Conceptual design and off-line validation– Safety analysis– 1997 human-in-the-loop experiment– Cost/benefit analysis– Avionics requirements study– Critical conflict geometry study– 1998 human-in-the-loop experiment

In collaboration with NASA, FAA and RLD

In summary

In detail


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1997 human-in-the-loop experimentMethod

Probe the limits– No Air Traffic Control– Air crew responsible for traffic separation

All aircraft in scenario fully equipped– Automatic Dependent Surveillance - Broadcast (ADS-B)– Conflict Detection & Resolution (CD&R)– Cockpit Display of Traffic Information (CDTI)

Cruise flight only– Direct routing– Optimal cruise altitude


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1997 human-in-the-loop experimentScenarios Traffic Densities:

– Single– Double– Triple

Level of Automation:– Manual– Execute Combined– Execute Separate

Non-Nominal:– Other aircraft failures/events– Own aircraft failures/events– Delay time increased


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1997 human-in-the-loop experimentResults

Acceptability: – 91.5% (single), 83.0% (double), 78.7% (triple)

Safety: – 88.3% (single), 75.5% (double), 71.3% (triple)

Workload:– ratings less than 40, indicating “costing some effort”

Across all densities, across all sessions, across all subject pilots, including non-nominal events


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Conclusion:

The feasibility of Free Flight with

Airborne Separation Assurance

could not be refuted

1997 human-in-the-loop experiment Conclusion and Issues raised

Issues raised:– Prevent short term intrusions of protected zones due to

sudden maneuvers of proximate aircraft– Transition to Free Flight (Airspace) – Mixed equipped traffic scenarios


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1998 human-in-the-loop experimentResearch questions to answer

How to accommodate mixed equipage in a transitional free flight era ?

What will a future ATM system containing Free Flight elements look like ?

Will there be a clear distinction between Managed Airspace (MAS) and Free Flight Airspace (FFAS) or can it be mixed ?

What is the role and responsibility of the ground controller and pilot ?


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1998 human-in-the-loop experimentMethod

Improved ASAS equipment:– to prevent sudden maneuvers of nearby aircraft

Three newly developed ATM operational scenarios: – to study the transition to Free Flight Airspace (in space)

Two levels of equipage and traffic density:– to study the transition towards Free Flight in time

The experiment contained an air (flightdeck) and ground side (ATC) which shared traffic scenarios


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1998 human-in-the-loop experimentASAS equipment

The Airborne Separation Assurance System (ASAS):

– Automatic Dependent Surveillance - Broadcast (ADS-B), Traffic Information Service - Broadcast (TIS-B)

– Conflict Detection and Resolution (CD&R)

– Cockpit Display of Traffic Information (CDTI)

– Predictive ASAS (PASAS)

– Alerting logic


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ASAS equipmentConflict Detection & Resolution

ownship

intruder

minimum distance

protected zone intruder

avoidance vector

advised vector

1. heading change

2. speed change

not shown: 3. vertical speed change


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ASAS equipmentCockpit Display of Traffic Information

Navigation Display– Traffic Symbology– Conflict Detection– Resolution Advisories– Vertical Navigation Display– Extra EFIS Control Panel

functionality


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ASAS equipmentPredictive ASAS

“no-go” bands for– track/heading– vertical speed– speed


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1998 human-in-the-loop experimentATM Scenarios

Starting points:– equipping aircraft should be immediately beneficial to the

airlines– equipping should be economy driven instead of mandatory– benefit the equipped aircraft, without excluding the

unequipped aircraft

Three ATM operational scenarios with Free Flight elements defined, implemented and tested:– Flight Level– Protected Airways– Full Mix


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1998 human-in-the-loop experimentATM Scenarios: Flight Level

Airspace above a certain altitude (the “Lower Free Flight level”, FL260) is reserved for equipped aircraft only

Transition layer used as a buffer zone for aircraft transitioning to and from Free Flight

Flying high is beneficial


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1998 human-in-the-loop experimentATM Scenarios: Protected Airways

The airspace structure remains intact

Unequipped aircraft are ground controlled and have to stay on airways

Equipped aircraft have the right to leave the airways for direct shortcuts

Direct routing is beneficial


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1998 human-in-the-loop experimentATM Scenarios: Full Mix All aircraft fly direct, free routing

Unequipped aircraft are ground controlled (ATC)

ATC performs conflict resolution for unequipped aircraft using a longer look-ahead time for conflict probing

Unequipped aircraft will always avoid equipped aircraft, beneficial for the equipped aircraft


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1998 human-in-the-loop experimentExperimental design

Experiment matrix:– Traffic Density - low density versus high density– Equipage - 25% versus 75% ASAS equipped– ATM operational concept - Flight Level, Protected Airways

and Full Mix

The high traffic density, Flight Level ATM condition was excluded

8 pilot subjects


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1998 human-in-the-loop experimentResults: Acceptability

Scale:– Perfect in every

way = 5– Favourable = 4 – Acceptable = 3– Unacceptable = 2– Completely

unacceptable = 1

Subjective Acceptability

0

1

2

3

4

5

Low Dens25%

High Dens25%

Low Dens75%

High Dens75%

airways

mixed

flight level


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1998 human-in-the-loop experiment Results: Safety

Subjective Safety

0

1

2

3

4

5

Low Dens25%

High Dens25%

Low Dens75%

High Dens75%

airways

mixed

flight level

Scale:– FF much safer = 5– FF safer = 4– same as ATC = 3 – ATC safer = 2 – ATC much safer = 1


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1998 human-in-the-loop experiment Results: Workload

Subjective by means of questionnaires with Rating Scale of mental Effort (RSME)

Objective by means of Eye-Point-Of-Gaze measurements

Scan randomness (entropy) used as objective metric for Workload


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1998 human-in-the-loop experiment Results: Workload

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%


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1998 human-in-the-loop experiment 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 flightdeck crew was able to handle higher traffic densities than the ground controller


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1998 human-in-the-loop experiment Future plans

Verify all assumptions:– “multi-pilot and multi-controller in the loop” experiment is

planned using Internet gaming facilities– ADS-B characteristics– Flight testing using “real” data

Study the integration of traffic, weather and terrain information in the cockpit


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Contact / More information

http://www.nlr.nl/public/hosted-sites/[email protected]

World Aviation Congress 1999, 99WAC-111 San Francisco, 19 October 1999

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Transcript of World Aviation Congress 1999, 99WAC-111 San Francisco, 19 October 1999