HIGH DENSITY EN ROUTE AIRSPACESAFETY LEVEL AND COLLISION RISKESTIMATION BASED ON STOREDAIRCRAFT TRACKS(EIWAC 2010)+E. Garcia*, F. Saez**, R. Arnaldo*** CRIDA (ATM Research, Development and Innovation Reference Centre)
Madrid, Spain
egarcia@crida.es**Air Navigation Department
Universidad Politécnica de Madrid (UPM)
Madrid, Spain
franciscojavier.saez@upm.es
rosamaria.arnaldo@upm.es

CRIDA an Initiative from Aena
(ATM Research, Development and Innovation Reference Centre)

Transport Engineering
Company

University
Spanish Air Navigation
Service Provider

Result Oriented
Scientific Rigour
Flexibility
CRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/20102

Outline• INTRODUCTION• NEED FOR A NEW COLLISION RISK MODEL• BACKGROUND• 3D CRM – GOAL
• 3D CRM – GENERAL DESCRIPTION• RADAR DATA PROCESSING• SAFETY METRICS• CONCLUSIONS AND WORK IN PROGRESSCRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/20103

INTRODUCTIONEUROCONTROL has worked in the last years todevelop the 3-D collision risk model (CRM).
ATCO
The 3-D collision risk model was developed as a general mathematicalframework to assess the level of safety in continental en-route
airspace, where controllers monitor air traffic by means of radar
surveillance and provide aircraft with tactical instructions

The objective of the software prototype tool is not only toeventually produce an estimation of the level of safety
achieved in the airspace under assessment but also toprovide safety-related metrics and trends, which can bemonitored over time.

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NEED FOR A NEW COLLISION RISKMODELPrevious models no not appropriate assess and monitor the level of safety in highdensity en-route radar airspaces using as a sole source of input data therecorded aircraft trajectories. Traditional approaches to Collision Risk Models (CRM), do not
capture the complexity inherent to an operational radar environment like the one in Europe,with high amount of traffic, a large number of crossings tracks, climbing and descending
aircrafts and complicated route structure.
PHASE

EN-ROUTEMODELO
Airwaystructure
consisting of one ormore parallel routes.
No radar surveillance.
ImprovementofCollision Risk Models
Parallelroutes.
Surveillance base don
ADS.
Precision approaches

TMA

CRIDA. CRM 3D.

Landing on closely andultra closely spaced
runways
Futureoperational
concepts

CRM Reich (1960)
Extended
Reich (1993)

CRM

CRM ADS (1993)
CRM ILS (1980)
BRM (1990)
MIT (1997)
NLR (2001)

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BACKGROUND
Nowadays, ANSP and Civil Aviation Authorities (CAA) mainly use ATM
accident and incident databases to monitor and provide evidence of levels ofsafety. However, although these databases are very powerful tools and are
improving constantly, they still have some weak points that need to beconsidered:•Not all incidents are reported by pilots and air traffic controllers. In fact, it
is very difficult to infer how many real incidents have occurred for each one
that is reported.
•Incident severity is generally ranked solely on how close aircraft get,without considering the geometry of the event or other parameters, e.g.
closure rate.
•Incident Classification is not homogeneous in all databases. Furthermore,
special care has to be taken to train database personnel so that the sameclassification criteria always apply.
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BACKGROUND
Airspace information

Meteo Information

E.g. AIS, Capacity, Demand

E.g.: METAR,……

Airports Data
E.g.: AIS,…

MANAGEMENT
AND ANALYSISOF
INFORMATION

Aviation accidents andIncidents
Aviation Maintenance
Incident Database

ATC Procedures

Aircraft Performances
E.g.. BADA,…

Real Aircraft Trajectories
Aircrafttrajectories from
Simulations

E.g. :radar data, ADS,…

E.gg: RTS, FTS,…

CRM 3DCRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)

ANALYSIS,ASSESSMENT AND
MONITORING OF
OPERATIONAL SAFETY
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3D CRM – GOAL
A major objective of the 3-D CRM tool is to complement the
information collected in the accident and incident databases,
thereby providing:
1. Identification of all proximate events based on radar data.
2. Complete classification of all proximate events using clear andconsistent criteria.

3. Detailed information on the evolution of each proximate event.
4. Collision risk estimate

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3D CRM – GENERAL DESCRIPTION

Airspace
Scenario

Traffic Sample

3D CRM
AnalyticalModel

3D CRM Radar
Analysis Tool

SafetyLevel
Estimation

Safety Event
Reports

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3D CRM – GENERAL DESCRIPTION

Radar Data Processing Module

Parameter Estimation Module

Radar Data Files
Airspace
Scenario

Identify
Proximate
EventsAnalyse andClassify
Events

Probability of
Risk
Other Safety
Metrics

Segmentation
Coarse Filter

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RADAR DATA PROCESSING
The radar data processing module comprises two different :•decoding and storage of radar track and flight plan files, and•track segmentation of radar data.
5

5

5

4

4

3

3

YY(m)

Y
Y (m)

x 10
5

2

1

0

0

-1

-1
-2

-1

0

X

X (m)

CRIDA. CRM 3D.

2

1

-3

1

2

x 10

-3

-2

-1

0

5

x 10

X

X (m)

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2
5

x 10

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RADAR DATA PROCESSINGGOAL ->Identify Proximate Events:

Conflicts
Potential Conflicts
Potential Collisions

Collision:
Aircraft physical separation< aircraft physical sizes
R

Conflict:
2H
Aircraft physical separation< intended margin (D, H)

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RADAR DATA PROCESSING
Look-ahead time (LAT): is the time horizon within which all aircraft positions
are projected to explore existence of “potential conflicts/collision”.

-> 10 minutes
CPA
D*

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RADAR DATA PROCESSING

MAP of HOT SPOTSCRIDA. CRM 3D.

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SAFETY METRICS ESTIMATION

Analysis of Proximate EventsClassification of Proximate Events
Detection of Activated Alert Systems
Identification of ATM System
Weaknesses
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SAFETY METRICS ESTIMATION
Analysis of Proximate Events
CPA(t cpa ,[r12]cpa,[h12]cpa)
v2
t cpa : time at CPA[r12]cpa: horizontal separation at CPA[h12]cpa: vertical separation at CPA

v1

tCI
CRIDA. CRM 3D.

[r12]cpa<R & [h12]cpa<H
tCI : time of identification of potential
conflict
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SAFETY METRICS ESTIMATION
Analysis of Proximate Events
New CPA*(t* cpa ,[r12]*cpa,[h12]*cpa)
v2

Change in the Rate ofClimb (ROC)v1 *tCI tmCRIDA. CRM 3D.

t cpa *: new time at CPA[r12]cpa *: new horizontal separation at CPA[h12]cpa *: new vertical separation at CPA[r12]cpa * <R & [h12]cpa * <Ht m: time of maneuvre

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SAFETY METRICS ESTIMATION
Analysis of Proximate Events

v2
Climb->Levelv1[h12]cpa : vertical separation at CPA[h12]cpa >HtCI tmCRIDA. CRM 3D.

tCR

t m: time of a conflict resolution manoeuvre

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SAFETY METRICS ESTIMATION
Analysis of Proximate EventsH
r12: actual horizontal separation
h12: actual vertical separation
r12 <R & h12 =HtCI tmCRIDA. CRM 3D.

tCF

t m: time to entry into conflict volume

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/201019

SAFETY METRICS ESTIMATIONClassification of Proximate Events
PROXIMATE EVENTCRITERIA

VERTICALREGIMERELATIVEHEADING

A/C REACTION

ACTIVATED ALERTSYSTEM

Same

Change Vertical
ProfileTCAS RA

Climb-Level(CL)Opposite

Modify Heading

TCAS TA

Descend-Level(DL)

Crossing

Change of Speed

STCA

No Reaction

No Alert

NATURE

TRAFFIC TYPE

Passing Event

Civil Traffic

Level-Level (LL)

Conflict

Both Military
AircraftPotential Conflict

One Military
AircraftPotential Collision

Climb-Climb(CC)False Detection

Climb-Descend(CD)Descend-Descend(DD)

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SAFETY METRICS ESTIMATION
Detection of Activated Alert Systems
t3 :Time-to-go to CPA
t2 :Time to Conflict
tCI

tCR

tCF

tCPA

Aircraft 2

t1 : Overall
Reaction Time[r12]CPA
Aircraft 1
R

tCI: identification of potential conflicttCR: start of a conflict resolution manoeuvre
tCF: predicted time of entry into conflict volume
tCPA: predicted time of CPA[r12]cpa: horizontal separation at CPA

t1=tCR-tCI
t2=tCF-tCI
t3=tCPA-tCI

Predicted trajectory
CRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/201021

SAFETY METRICS ESTIMATION
Detection of Activated Alert Systems
TIME TO CPASTRATEGIC( Risk )Potential
Collision

Yes

Safety Barriers
TACTICAL
4 minsTCAS RATCAS TATACTICALBASED ON STCA

(See & Avoid,..)48 sec2 mins35 sec No lossof Sep.

No

P(Pre  Tactical Failure )Yes

No lossof Sep.

No

No lossof Sep.

Yes

P(Tactical Failure )No

Yes

P ( STCAFailure )Loss of
Separation?

No

P(TCAS TAFailure )Yes

Loss of
Separation

No

P(TCAS RAFailure )Collision

TIME TO CPA
4 minsCRIDA. CRM 3D.

2 mins48 secENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)35 sec11/10/201022

VERTICAL SEPARATION (feet)

SAFETY METRICS ESTIMATION
Detection of Activated Alert Systems
2 min
48 secStrategic
ATC Action

TacticalATC Action(STCA)

Traffic
Advisory (TA)35 secH

Resolution
Advisory (RA)

850
600

VERTICAL CLOSURE RATE (fpm)
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SAFETY METRICS ESTIMATION
Detection of Activated Alert Systems
HORIZONTAL PLANE
x 10

VERTICAL PLANE

5

380

1
370

0.5

Y

Y

(FL)
Altitude(FL)
Altitude

360

0

RA

-0.5

0.0 f pm

350

RA
1875.0 f pm

340

330

-1
320

-5

-4.5

-4

-3.5

-3
X

-2.5

22.6

-2
x 10

22.65

22.7

5

204.0 kts

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22.8 22.85
time (h)

22.9

22.95

23

23.05

Time (h)11/10/201024

Proximate Event Data: AC 1 - AC 2
Tm [r12]cpa [h12]cpa TTC Dur TCPA Manoeuvre
rel
AC1
T0

T1

T2

T3

T4

T5

(NM)

(ft)

(min)

(min)

0.66

-0.00

5.99

1.67

-0.42

00.00

-5.12

0.24

0.00

0.86

0.01

-0.00

-0.40

0.25

0.00

0.46

0.11

1000.00

-0.23

0.36

1000.00

0.22

-0.01

00.00

-0.22

0.34

1000.00

0.00

2.44

-0.00

0.00

2.79

1000.00

0.00

CRIDA. CRM 3D.

Manoeuvre
AC2

0.00
-0.00

5.12

0.48

0.80

Turn 5.7º

AC1 Turn ; ><

-0.00
0.00

0.24

>Conv(85º)<

-0.00
-0.00

0.40

LegendTCAS RACL  FL

AC2 CL  FL ;  VER SEP; >Conv(88º)<

0.00

CONFLICT RESOLVED-VERTICAL PLANE-0.03>Conv(93º)<-0.03

MIN REAL SEP: 0.3 NM 1000 ft

0.29<Div(99º)>

0.26

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50

8000

T0

45

7000

Horizontal Distance (nm)35

Vertical Separation (ft)Resolution Advisory
Traffic Advisory
Tactical ATC Action (STCA)
Strategic ATC Action

40

30
25
20
15

6000
5000
4000
3000
T1
2000

10

T1

5

T3

0

Resolution Advisory
Traffic Advisory
Tactical ATC Action (STCA)
Strategic ATC Action

T4
T3

1000

T4
0

100

200

300

400

500

600

Horizontal Closure rate (kts)

700

800

900

0

0

1000

2000

3000

4000

5000

6000

Vertical Closure Rate (fpm)

As an example, this figure represents in the TCAS and STCA diagram the evolution of the encounter
described beforte. A TCAS RA is activated if the kinetic and geometric characteristics of the eventin the horizontal plane and in the vertical plane are in the red area at the same time.
CRIDA. CRM 3D.

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SAFETY METRICS ESTIMATION
Identification of ATM System Weaknesses
Risk Context

Qualification of Hazards

Initiating events leading
to potential collisions

Effectiveness of Safety
Barriers

Detection / Resolution ofpotential collisions
ATCO STCA

TCAS …

Traffic Density
No Safety Effect+Traffic complexity+

HAZARD(potential collision)

Conflict

ATC/Pilot Errors+

Collision

Technical Failures
CRIDA. CRM 3D.

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SAFETY METRICS ESTIMATION
Identification of ATM System Weaknesses
Risk Context (within
selected area/timeframe)
Flight-Time

Hot Spots

Number of Movements
Kinematics(Speed, Type of Aircraft)
Nº of Entries and Exits
Route structure

Traffic Density

Effectiveness of
Safety Barriers

Qualification of Hazards

Number of Real Conflicts
Overall Reaction TimeClassification of Proximate
Events:• Nature• Traffic Type• Vertical regime• Relative heading• A/C Reaction• Activated Alert System(TCAS, STCA)

Number of Routes

Correlation between
Hot Spots andTraffic Density Maps.

% Evolving (non-level) Aircraft

Nº of potential collisions

Time Margin
Time to Conflict
Time-to-go to the CPA% of Potential Conflicts
solved in:• vertical plane and• horizontal plane
Average Nº of Aircraft “near”
a Proximate Event

Separation Rules
CRIDA. CRM 3D.

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SAFETY METRICS ESTIMATION
Identification of ATM System Weaknesses
Risk Context(within selectedarea/time-frame)Side Length=7.5 NM

CRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/201029

SAFETY METRICS ESTIMATION
Total Number of Proximate Events: 45389
5x 10

Qualification ofHazards

CIVIL-MILITARY TRAFFIC 5.6%
MILITARY TRAFFIC 3.2%

Total Number of Proximate Events: 35166

5

4

x 10

DESCENT-DESCENT 1.2%

4

CLIMB-DESCENT 6.4%

LEVEL-LEVEL 13.8%

3

CLIMB-CLIMB 11.9%

3
Total Number of Proximate Events: 41397

2
PASSING
EVENT 0.46%

LEVEL-DESCENT 7.1%

FALSE DETECTION 14.59%

2
1

ACTUAL CONFLICT 0.08%

1
CIVIL TRAFFIC 91.2%

00
LEVEL-CLIMB 59.6%-1-1

CIVIL-MILITARY TRAFFICMILITARY TRAFFICCIVIL TRAFFIC-2-2

POTENTIAL CONFLICT 84.86%-4-4

CRIDA. CRM 3D.

-3
-3

-2
-2

-1
-1

0
0

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1

TCAS RA
2
5
2
x 10
5
x 10

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SAFETY METRICS ESTIMATION
Overall Reaction
Time-to-go
to CPATime(t3) (t1)10Effectiveness of
Safety Barriers

900
700

9
800
600

90

TCAS TA 2.1%
TCAS RA 0.3%

80

8

70

Time-to-go to the CPA (min)

700

7

200

2

500
600

60
STCA 28.0%

6

50

400
500

400
300
300

5
40
4
30

3

200

100

ATC STRATEGY 69.6% 100

10

1

0 0 0
0 0 0 1 1 1

CRIDA. CRM 3D.

20

2 22

3 33

55 5 6 6 6 7 7
44 4
Overall
Reaction(min)
Time-to-go
to CPA(min)
Overall
Reaction
TimeTime(min)

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7

8 98

9

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0

10 10

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CONCLUSIONSThe 3-D CRM tool has been designed to complement the
information collected in the accident and incident databases,
thereby providing the following information inferred from the indepth assessment of proximate events:
Identification of all proximate events based on radar data.

Complete classification of all proximate events using clear and consistentcriteria.
Detailed information on the evolution of each proximate event.
Safety metrics and other air traffic factors
CRIDA. CRM 3D.

ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/201032

WORK IN PROGRESS•Apply the 3-D CRM too to traffic samples of different
airspaces and extend the principles of 3-D CRM from en-routeto Terminal Manoeuvring Area (TMA) scenarios;•Develop a methodology to provide a complete risk picture of
the scenario, identifying the ATM system weakness andcharacterizing the performance of the safety barriers, using all
the information provided by the 3-D CRM tool that could be
used by ATM service providers to monitor and improve safetylevels in their operation;•Complete an analytical model based on the 3-D CRM tool toprovide true collision risk values.
CRIDA. CRM 3D.

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Questions

CRIDA (Centro de Referencia I+D+i ATM)CRIDA.
CRM
3D.
CRIDA:
GeneralDescriptionENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010)11/10/201034