Nationaal Lucht- en Ruimtevaartlaboratorium National Aerospace Laboratory NLR CXXX-1A Free Flight with Airborne Separation will result in an uncontrolled,

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

Conceptual Design of Free Flight with Airborne Separation Assurance

Jacco Hoekstra

Ronald van Gent

Rob Ruigrok



CXXX-3A

Free Flight goals

User preferred routing– Horizontally

• direct to destination• optimum speed

– Vertically • optimum level• cruise climb

More capacity



CXXX-4A

Present day ATC control



CXXX-5A

User Preferred Routing



CXXX-6A

Airborne Perspective



CXXX-7A

Starting Points / Constraints

No ATC – Probe the limits

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

Cruise flight only– Direct routing– Optimal cruise altitude



CXXX-8A

Three sub-studies: Traffic Manager: Off-line simulations

– Find a suitable base-line concept– Create background scenario for Man-in-the-

Loop Simulation Experiment

TOPAZ (Traffic Organization and Perturbation AnalyZer)– Safety Analysis– Predict critical non-nominal situations

Man-in-the-Loop Simulation Experiment– Human Factors Issues– Validation of concept with Man-in-the-Loop



CXXX-9A

Several concepts tested– Altitude step– Cross product of speed vectors– Extended VFR rules– Variations of TCAS manoeuvres – Voltage potential

Modified Voltage potential validated– (Ref. M. Eby, Lincoln Laboratory)

Traffic Manager Runs



CXXX-10A

Modified Voltage PotentialIntruder’s

protected zoneHeading distance

Speed change Avoidance

vector

Minimum distance

Ownship

Intruder



CXXX-11A

Traffic & Experiment Manager



CXXX-12A

Traffic Manager Results

Fail Safe aspects– Both aircraft detect & resolute conflicts– Backup: TCAS, R/T

Scenarios for man-in-the-loop experiment:– Single, double & triple WE density– Events

0

1

2

3

4

5

6

7

8

Fuel Time Way Intru

Alt Step

Cross pr.

Voltage



CXXX-13A

Topaz Safety Analysis (1)

Two airways in opposite direction

Independent variables: route spacing, non-nominals

Dependent: Collision risk

ASAS equipped, airborne separation, good weather, no global ADS-B failure, independent transmitter & receiver

Airway

Airway

Route spacing



CXXX-14A

TOPAZ safety analysis (2)



CXXX-15A

TOPAZ safety analysis (3)



CXXX-16A

TOPAZ safety analysis(4)

Free Flight with Airborne Separation Assurance is feasible in comparison to current ATC

Biggest safety benefit will be achieved by dealing with the Non-Nominal/Nominal contribution



CXXX-17A

Man-in-the-loop simulation



CXXX-18A

Man-in-the-loop Simulation Configuration

AIRSIM

RFS

TEM



CXXX-19A

Experimental Design

• Place of non-nominals in matrix changed between subject crews

• 18 runs per crew

• air line pilots

• 2 days incl. half a dayof training



CXXX-20A

Man Machine Interface Modifications to Navigation Display

– Traffic symbology– Conflict detection– Resolution Advisories– Vertical Navigation Display– Extra EFIS Control Panel functionality

Modifications to Autopilot– Execute combined– Execute separate

Aural alerts

Dedicated blue light under glareshield



CXXX-21A

Navigation Display



CXXX-22A

Man-in-the-Loop experimentHypotheses

Less than acceptable

Less safe

More workload



CXXX-23A

Man-in-the-Loop experimentResults

Subjective Acceptability

3.44 3.553.34

1

2

3

4

5

Overallaverage

OverallaverageNominal

Overallaverage

NonNominal



CXXX-24A


Subjective Safety

3.10 3.003.21

1

2

3

4

5

Overallaverage

OverallaverageNominal

Overallaverage

NonNominal



CXXX-25A


Subject workload

0

20

40

60

80

100

120

140

single double triple

density

nominal

non-nominal



CXXX-26A


Subjective Workload

33.85 35.4228.76

0

20

40

60

80

100

120

140

first second third



CXXX-27A

Conclusions

Free Flight concept as implemented is acceptable in cruise phase

Workload in a future Free Flight scenario in cruise phase is not higher than in present day ATC scenario

Free Flight concept is at least as safe as present day ATC

None of the three sub-studies (off-line simulations, TOPAZ safety analysis, Man-in-the-Loop experiment) could refute the feasibility of an Airborne Separation Assurance concept for a future Free Flight environment.



CXXX-28A

Issues

Some form of obtaining intent information should be made available.

Aircraft, which are in trouble, should be able to broadcast a signal upon which they would receive priority with conflicts.

Passenger comfort

Fine tuning of conflict detection & resolution based on remarks of pilots



CXXX-29A

Demonstration PC version Traffic Manager

Resolution method

Ground & air perspective

Navigation display symbology

Documents

Nationaal Lucht- en Ruimtevaartlaboratorium National Aerospace Laboratory NLR CXXX-1A Free Flight with Airborne Separation will result in an uncontrolled,