Overview of NLR ASAS work Jacco Hoekstra Rob Ruigrok

Nationaal Lucht- en Ruimtevaartlaboratorium

National Aerospace Laboratory NLR

CXXX-1A



CXXX-2A



CXXX-3A

Outline Projects Overview

General Findings

ASAS Prototype Guidelines

The Next Steps

ASAS = Self-Separation in this presentation



CXXX-4A

Projects Overview

Free Flight (NASA, FAA, RLD, NLR)

INTENT (ONERA, QinetiQ, TU-Delft, Rockwell Collins, Smiths, Airbus, Eurocontrol, NLR, VNV, BA, SAS, KLM)

MFF (ENAV, AENA, Eurocontrol, DNA, SCAA, HCAA, MATS, NATS, NLR)

Conflict rate

0 100 200 300 400 500 600 700 800

900 1000

0 10 20 30 40 Number of aircraft in sector

Pc/

P2

Air Ground



CXXX-5A

Project Free Flight Analysis: Distributed systems, capacity, safety

Offline: normal scenarios, complex geometries

SIM I: Basic FF cruise, high densitiesSIM II: Mixed equipage in cruise, PASAS?MHITL: Web experiment & classroomSIM III: How low can you go?

NLR ASAS prototype based on state info & PASAS



CXXX-6A

Project Free FlightConflict Detection & Resolution

ownship

intruder

minimum distance

protected zone intruder

avoidance vector

advised vector

1. heading change

2. speed change

not shown: 3. vertical speed cange

Protected Zone radius = 5 nm ½h = 1000 ft

=>normally vertical most optimal

ASAS offers 3 separate manoeuvres



CXXX-7A

Project Free FlightASAS CDR&P

• ASAS: 5nm, 5 min, 1000 ft• Conflict symbology

- red circle & track- yellow circle own zone- traffic symbol always- label time to l.o.s.

• Resolution symbology- horizontal- vertical

• Predictive ASAS• If conflict =>

check vertical !



CXXX-8A

Human-in-the-loop experiment I

Conflict rate tripled: so 3x, 6x, 9x !

Low workload in high density en-route traffic

Workload - Traffic Density( p < 0.0086 )

0

10

20

30

40

50

Single Double Triple

RS

ME

ratin

g

114 = costing lots and lots of effort

88 = costing much effort

40 = costing some effort

27 = costing little effort

3 = costing no effort



CXXX-9A

Human-in-the-loop experiment II

Mixed-Equipage concept: 25% & 75% equippedAirborne side prefers Full mix Ground side not able to cope with Full mix

Traffic density lowered for ATCo relative to HITL I

Predictive ASAS lowers conflict alert rate significantly and makes alert time predictable



CXXX-10A

Human-in-the-loop experiment III

Descent: not different from cruise

Arrival: – FF higher workload– CDTI in managed airspace => extremely low workload

Workload for flight phase and procedure

0

5

10

15

20

25

30

35

40

45

Cruise Descent Arrival

RS

ME ATC

CDTI

FF








CXXX-11A

Multiple human-in-the-loop experiments

• Webexperiment• Classroomexperiment



CXXX-12A

Multiple human-in-the-loop experiment Humans

smarter, meaner, more strategic, emotional, variable, etc.

Will superconflict solving deteriorate or improve?

Superconflict n=8



CXXX-13A

Who are the bots and who are the humans?



CXXX-14A

Project INTENT(not an acronym)

The objective of the INTENT project is to answer these questions, giving a technology roadmap for airborne and ground based equipment to increase airspace capacity.

Where ?How ?

When ?

But:– how much INTENT is required ?– where to use INTENT ?– when to use INTENT ?

Aircraft intent is a potential enabler of Airborne Separation Assurance / Free Flight

Part task

Fast time

Full scaleMost interesting systems

Human acceptability

Parameters ofhuman operator

model

Literature study

Scope andcapacityconcepts

Possible validationsequence

Nominal validationroute



CXXX-15A

INTENT based CD&R RFS intent-based ASAS

– Conflict detection and resolution based on aircraft 3D position and FMS flight plan (aircraft intent)

– Priority rules, one aircraft in conflict manoeuvres– Resolution advisories in more directions and always

presented as an FMS modified route– Only when FMS is engaged (LNAV and VNAV)

Three alert levels:– 20 - 5 minutes: green– 5 - 3 minutes: amber– 3 - 0 minutes: red

Experimental Design– 4 intent levels: state-based with 5 min look-

ahead time, intent-based with 5, 10 and 20 min look-ahead time.

– 3 traffic loads: 1x, 2 x and 3 x today's traffic



CXXX-16A

INTENT Conclusions (1/2)

Including aircraft intent in the separation assurance process is preferred by controllers and pilots

Aircraft intent information does not have a significant effect on controller or pilot workload, compared to the references without aircraft intent, both for the airborne and ground concepts

Aircraft intent information has a positive effect on flight efficiency compared to state based references



CXXX-17A

INTENT Conclusions (2/2) The comparison between the airspace

capacity results of the airborne and ground concepts is interesting: – ground concepts

can handle aboutmaximum of1.5 times today’s traffic load

– airborne concepts can handle 3 times this load.

No

tool

Stat

e

Inte

nt 5

Inte

nt 1

0

Inte

nt 2

0Ground / Structured

Ground / Unstructured

Airborne / Unstructured

3 3 3 3

1.51.5

1.31.3

0

1

2

3Tr

affic

Loa

d

Intent Level

Operational Concept

Achievable Traffic Load

Ground / Structured

Ground / Unstructured

Airborne / Unstructured



CXXX-18A

Project MFF ASAS trials ASAS in climb,cruise & descent

Transition FFAS MAS

FL285



CXXX-19A

Project MFF, results

Vertical transitions have highest workload

Instantaneous Self-Assessment (ISA)Average (95% confident)

Transition

EXTREME

HIGH

MEDIUM

LOW

NO

Instantaneous Self-Assessment (ISA)Maximum values

Transition

EXTREME

HIGH

MEDIUM

LOW

NO



CXXX-20A

Project MFF, results

Workload higher with ASAS but acceptable

Instantaneous Self-Assessment (ISA)Average (95% confident)

PF / reference PF / ASAS PNF / reference PNF / ASAS

Role / ASAS

EXTREME

HIGH

MEDIUM

LOW

NO

Instantaneous Self-Assessment (ISA)Maximum values

PF / reference PF / ASAS PNF / reference PNF / ASAS

Role / ASAS

EXTREME

HIGH

MEDIUM

LOW

NO



CXXX-21A

General Findings

ASAS yields tremendous capacity increase

ASAS offers safety benefits

ASAS allows direct routing and optimal vertical profile, hence efficiency benefits

State-based CDR&P sufficient for introduction and benefits, intent-based system preferred for future



CXXX-22A

ASAS Prototype Guidelines Separate or duplicate ADS-B transmitter/receiver

State-based lookahead time 5-7 minutes in cruise, descent & climb is sufficient if fitted with predictive ASAS

Target altitude as intent info would enhance system

Intent based CD&R can expand lookahead time, optimum found to be 10 minutes

Use of priority (to 3 min to l.o.s. at the latest):– to allow state-based, state-based + target state and

intent-based CDR&R to operate in the same airspace– reduction of workload: only 1 aircraft to manoeuvre

Co-operative resolution offers fail-safety and offers bottleneck solution by wave/domino effect



CXXX-23A

Next Steps

Test bandwidth

Standardise on principle of co-operative resolution

Develop standards for intent-based system for future that is compatible with first generation ASAS

And then:

It is time for a leap forward

=> Retrofit state-based system during field trials in non-radar airspace: North Atlantic?



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Project Free FlightConcept: state-based, co-operative Lookahead time is 5 minutes

Two alert levels: 5-3 minutes: amber 3-0 minutes: red

Normally: – amber: vertical resolution each solves 50% of intrusion in

amber conflicts– red always each 100 % (fail-safe) vertical

Exception: horizontal resolution both solve 100% of intrusionvert/vert = 50+50 v & 0 h = solved verticallyhor/vert = 50+0 v & 100 h = solved horizontallyhor/hor = 80 + 80 h & 0 v = solved horizontally



CXXX-27A

Project Free FlightPrimary flight display

Conflict reso:- vertical spd- altitude- heading- speed(green bugs)

Predasas on:- vertical spd- speed- heading(amber & red bands)



CXXX-28A

Capacity

Distributed system vs. central system

Effect on workload, safety and technological requirements

221 )1( pNNp

gc

2)1( pNpac

Conflict rate

0 100 200 300 400 500 600 700 800

900 1000

0 10 20 30 40 Number of aircraft in sector

Pc/

P2

Air Ground



CXXX-29A

Capacity - Workload

Workload - Traffic Density( p < 0.0086 )

0

10

20

30

40

50

Single Double Triple

RS

ME

ratin

g

Conflict rate: triple, six times, nine times !



CXXX-30A

Capacity

221 )1( pNNp

gc

2)1( pNpac

Task comparison Controlled vs. Free Flight

Fly

Navigate

Communicate with ATC

Fly

Navigate

Separation

Controlled Flight Free Flight



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Safety



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Safety



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Safety



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Safety



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Safety



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Safety



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Workload

Descent: no different from cruise

Arrival: – FF higher workload– CDTI and managed extremely low workload

Workload for flight phase and procedure

0

5

10

15

20

25

30

35

40

45

Cruise Descent Arrival

RS

ME ATC

CDTI

FF








CXXX-38A

ASAS prototype Retrofit: State-based with conflict prevention minimal

required, target state (altitude) recommended

Lookahead time 5-10 minutes

En-route: climb, cruise, descent

Approach: extra tools needed (spacing)

Effects on safety, capacity, efficiency all expected to be beneficial. Workload acceptable.

Air Traffic Control becomes Air Traffic Management

Overview of NLR ASAS work Jacco Hoekstra Rob Ruigrok

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