4 th Workshop, Amsterdam, 23 rd -25 th April 2007 ASAS LC&P Applications in Radar Airspace:...

4th

Workshop, Amsterdam, 23rd

-25th

April 2007

ASAS LC&P Applications in Radar Airspace:

Operational Scenario Example and Fast-Time Simulation Results

Thierry Miquel and Philippe Louyot

DSNA, Toulouse, France

John Anderson and Colin GoodchildUniversity of Glasgow, UK

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Contents

• ASAS Resolution Manoeuvres• Operational Procedure• Fast-Time Simulation Results

– Operational scenarios– ASEP-LC&P algorithms assessment

• Conclusions

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ASAS Resolution Manoeuvres

• Finite time-horizon (look ahead time 5-10 minutes)

• Lateral manoeuvre requirement only

• Third-party aircraft assumed isolated from ASAS designated pair

• Two well-established resolution manoeuvre classes have been assessed– Turning point manoeuvre– Offset manoeuvre

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• Turning point manoeuvre– Minimizes the number of resolution manoeuvre stages– May be achieved through autopilot lateral functionality

Target aircraft Clearance aircraft

Suggested TCP

Clear of Traffic Point

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• Offset manoeuvre– May be compatible with Flight Management System (FMS)

functionality

– A track alteration of 30 degrees has been assumed

Target aircraft Clearance aircraft

Suggested TCPs

Clear of Traffic Point

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Contents



• Conclusions

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Operational Procedure - Phases

Set-up Phase

Identification Phase

Clearance Phase

Execution Phase

Termination Phase

ControllerFlight crew

Set-up Phase

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Operational Procedure - Example

ATCO: CSA6662 For Lateral Crossing, identify Target AF534

ATCO assesses the opportunity of ASAS lateral crossing manoeuvre

Setup phase + Setup phase + Identification phaseIdentification phase

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Pilot: CSA6662 Identify AF534

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Pilot: CSA6662 Target Identified AF534, two o’clock, 38NM

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ATCO: CSA6662 Pass behind [AF534], report clear of traffic, then proceed to MOKDI

Clearance phaseClearance phase

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Pilot: CSA6662 Pass behind AF534 then proceed to MOKDI (Clearance entered and solution evaluated)

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Flight crew aligns aircraft track by means of the Flight Control Unit.Alternatively, the solution can be coupled to the FMS functionalities.

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ATCO: AF534BH for information you are under ASAS separation

Execution phaseExecution phase

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Pilot monitors the expected separation (by means of relative ground speed vector)

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Clearance aircraft near the Closest Point of Approach.

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Clearance aircraft passed CPA and close to Clear of Traffic.

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Pilot: CSA6662 clear of traffic, proceeding to MOKDI

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ATCO: Roger, CSA6662, (instruction)

ATCO assesses that separation at COT is OK and resumes responsibility for separation

Termination phaseTermination phase

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Pilot: CSA6662 Proceeding to MOKDI End of ASAS – pilot resumes navigation monitoring.

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Contents


– Operational scenarios– ASEP-LC&P algorithm assessment

• Conclusions

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Fast-Time Simulation Results• Operational scenarios

– Derived from pairwise crossing encounters in radar airspace in two adjacent sectors in southwest France:

Sector T

Sector W

Ac147

Ac41

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Fast-Time Simulation Results

• The selected radar set is modified such that aircraft are flying directly from the entry point to the exit point of the sector.

• Only encounters for which the initial separation is greater than 5 NM are considered (a total of 309 encounters).

• The clearance aircraft (ASAS equipped aircraft) is assumed to be the aircraft with the lowest airspeed

• Pass behind manoeuvres are simulated

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• Navigation accuracy model:

– The aircraft is assumed to follow a succession of waypoints.

– The aircraft is assumed to be equipped with a track-hold autopilot.

– Lateral positioning errors are included in the track-hold autopilot control to simulate the required 95% accuracy navigation positioning.


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• Example of an encounter with 1 NM navigation error for both aircraft


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• Simulations were performed for each of the selected encounters for each of nine wind fields and three navigation error categories:

– Wind fields: {0 kts, 30 kts, 60 kts} x {0˚, 90˚, 180˚, 270˚}

– Navigation positioning categories: {0, 0.3, 1} NM

• Focus on the set of uncontrolled encounters for which the separation is lower than 5 NM (1086 encounters)

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Contents

• ASAS Resolution Manoeuvres• Operational scenario example• Fast-Time Simulation Results


• Minimum lateral separation• Maximum cross track deviation

• Conclusions

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• The objective of the ASEP-LC&P algorithms is to achieve a prescribed minimum lateral separation (5 NM in this case)

• Two performance metrics are used to assess the ASEP-LC&P algorithms:– Minimum lateral separation achieved

– Maximum cross-track deviation

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• For each encounter/wind field/navigation accuracy scenario, each of the performance metrics was assigned to one of the bin sets:

– Bin 1: the metric value is between 0 NM and 2 NM



– …

– Bin 7: the metric value is greater than 12 NM

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Contents




• Conclusions

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ASEP-LC&P Algorithms Assessment

• Minimum lateral separation– No lateral crossing manoeuvre

No Lateral Crossing Maneuver

0

5

10

15

20

25

30

35

40

45

50

Bin 0-2 NM Bin 2-4 NM Bin 4-6 NM Bin 6-8 NM Bin 8-10NM

Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM

Minimum lateral separation

Percentage of encounters per bin category

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• Minimum lateral separation– No lateral crossing manoeuvre


0

5

10

15

20

25

30

35

40

45

50


Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM




0

5

10

15

20

Bin 4-4,75 NM Bin 4,75-5,25 NM Bin 5,25-6 NM

Nav. Error 0

Nav. Error 0,3

Nav. Error 1


0

5

10

15

20


Nav. Error 0

Nav. Error 0,3

Nav. Error 1

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Turning Point Maneuver

0

20

40

60

80

100

120


Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM



• Minimum lateral separation– Turning point manoeuvre

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0

20

40

60

80

100

120


Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM



• Minimum lateral separation– Turning point manoeuvre


0

20

40

60

80

100


Nav. Error 0

Nav. Error 0,3

Nav. Error 1


0

20

40

60

80

100


Nav. Error 0

Nav. Error 0,3

Nav. Error 1

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Offset Maneuver

0

10

20

30

40

50

60

70

80

90

100


Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM

• Minimum lateral separation– Offset manoeuvre

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Offset Maneuver

0

10

20

30

40

50

60

70

80

90

100


Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM

• Minimum lateral separation– Offset manoeuvre

Offset Maneuver

0

10

20

30

40

50

60


Nav. Error 0

Nav. Error 0,3

Nav. Error 1

Offset Maneuver

0

10

20

30

40

50

60


Nav. Error 0

Nav. Error 0,3

Nav. Error 1

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• Example of unresolved conflict:– Despite a separation of 19.4 NM at the beginning of the

encounter, the two aircraft cross at 2.3 NM.

– This example basically shows that if the clearance is issued late, the radius of turn may not be sufficient to enable the clearance aircraft to correctly perform the lateral crossing manoeuvre.

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Contents




• Conclusions

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• Maximum cross-track deviation– Turning point manoeuvre


Maximum cross-track deviation


0

5

10

15

20

25

Bin 0-2NM

Bin 2-4NM

Bin 4-6NM

Bin 6-8NM

Bin 8-10NM

Bin 10-12 NM

Bin >12NM

Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM

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• Maximum cross-track deviation– Offset manoeuvre


Maximum cross-track deviation

Offset Maneuver

0

5

10

15

20

25

Bin 0-2NM

Bin 2-4NM

Bin 4-6NM

Bin 6-8NM

Bin 8-10NM

Bin 10-12 NM

Bin >12NM

Nav. Error 0 NM

Nav. Error 0,3 NM

Nav. Error 1 NM

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Contents



• Conclusions

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Conclusions

• Two well-established resolution manoeuvre classes have been investigated using a state-based geometric resolution algorithm:– Turning point manoeuvre and– Offset manoeuvre

• Only pass behind manoeuvres have been investigated as far as they are perceived by air traffic controllers as safer than pass in-front manoeuvres

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Conclusions

• Assessment, conducted using a set of modified radar encounters, indicates that:– Turning point manoeuvres perform better than

offset manoeuvres but provide a greater maximum cross track deviation.

– In addition, navigation errors (either from the ownship or from the target) significantly increase the percentage of unresolved conflicts by the airborne system.

– Close links should exist between future airborne separation standards and navigation performance.

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Conclusions

• A static manoeuvre envelope may not be adequate to take advantage of lateral crossing manoeuvre opportunities.

• Depending on the initial position and velocity configuration of the conflicting aircraft, a static envelope may be over- or under-sized.

• Envelope issues could be overcome by means of a dynamic manoeuvre envelope or by broadcasting the intended lateral crossing manoeuvre.

4 th Workshop, Amsterdam, 23 rd -25 th April 2007 ASAS LC&P Applications in Radar Airspace:...

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