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

1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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 Conclusion: The feasibility of Free Flight with Airborne Separation Assurance could not be refuted

9. 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 ?

10. 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

11. 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

12. protected zone intruder minimum distance 1. heading change avoidance vector 2. speed change advised vector ASAS equipmentConflict Detection & Resolution ownship not shown: 3. vertical speed change intruder

13. ASAS equipmentCockpit Display of Traffic Information • Navigation Display • Traffic Symbology • Conflict Detection • Resolution Advisories • Vertical Navigation Display • Extra EFIS Control Panel functionality

14. ASAS equipmentPredictive ASAS • “no-go” bands for • track/heading • vertical speed • speed

15. 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

16. 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

17. 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

18. 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

19. 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

20. 1998 human-in-the-loop experimentResults: Acceptability • Scale: • Perfect in everyway = 5 • Favourable = 4 • Acceptable = 3 • Unacceptable = 2 • Completely unacceptable = 1

21. 1998 human-in-the-loop experiment Results: Safety • Scale: • FF much safer = 5 • FF safer = 4 • same as ATC = 3 • ATC safer = 2 • ATC much safer = 1

22. 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

23. 1998 human-in-the-loop experiment Results: Workload Subjective: Objective:

24. 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

25. 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

26. Contact / More information http://www.nlr.nl/public/hosted-sites/freeflight ruigrok@nlr.nl