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HIGH DENSITY EN ROUTE AIRSPACE SAFETY LEVEL AND COLLISION RISK
ESTIMATION BASED ON STORED AIRCRAFT TRACKS
(EIWAC 2010)
+E. Garcia*, F. Saez**, R. Arnaldo*** CRIDA (ATM Research, Development and Innovation Reference Centre)
Madrid, Spain
**Air Navigation Department
Universidad Politécnica de Madrid (UPM)
Madrid, Spain
CRIDA. CRM 3D. ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010) 11/10/2010 2
CRIDA an Initiative from Aena(ATM Research, Development and Innovation Reference Centre)
Scientific Rigour
Result Oriented
Flexibility
UniversitySpanish Air Navigation
Service Provider
Transport EngineeringCompany
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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 PROGRESS
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INTRODUCTION
EUROCONTROL has worked in the last years to develop the 3-D collision risk model (CRM).
The 3-D collision risk model was developed as a general mathematical framework 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
ATCO
The objective of the software prototype tool is not only to eventually produce an estimation of the level of safety achieved in the airspace under assessment but also to provide safety-related metrics and trends, which can be monitored over time.
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NEED FOR A NEW COLLISION RISK MODEL
Previous 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 notcapture 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 descendingaircrafts and complicated route structure.
PHASE MODELO
EN-ROUTE
Airway structureconsisting of one ormore parallel routes.No radar surveillance.
CRM Reich (1960)
Improvement ofCollision Risk Models
Extended CRMReich (1993)
Parallel routes.Surveillance base donADS.
CRM ADS (1993)
TMA
Precision approaches CRM ILS (1980)
Landing on closely andultra closely spacedrunways
BRM (1990)
MIT (1997)
Future operationalconcepts
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 of safety. However, although these databases are very powerful tools and are improving constantly, they still have some weak points that need to be considered:
•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 same classification criteria always apply.
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BACKGROUND
MANAGEMENT AND ANALYSIS
OF INFORMATION
Aircrafttrajectories fromSimulationsE.gg: RTS, FTS,…
Aircraft PerformancesE.g.. BADA,…
ATC Procedures
Airports DataE.g.: AIS,…
Airspace informationE.g. AIS, Capacity, Demand
Meteo InformationE.g.: METAR,……
Aviation accidents and Incidents
Aviation MaintenanceIncident Database
Real Aircraft TrajectoriesE.g. :radar data, ADS,…
CRM 3DANALYSIS,
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 and consistent criteria.
3. Detailed information on the evolution of each proximate event.
4. Collision risk estimate
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3D CRM – GENERAL DESCRIPTION
AirspaceScenario
3D CRM Analytical
Model
Safety Level
Estimation
3D CRM Radar Analysis Tool
Traf
fic
Sam
ple
Safety Event Reports
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3D CRM – GENERAL DESCRIPTION
AirspaceScenario
Radar Data Files
Identify Proximate
Events
Analyse and Classify Events
Probability of Risk
Other Safety Metrics
Segmentation
Coarse Filter
Radar Data Processing Module Parameter Estimation Module
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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.
-3 -2 -1 0 1 2
x 105
-1
0
1
2
3
4
5x 10
5
X
Y
-3 -2 -1 0 1 2
x 105
-1
0
1
2
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5x 10
5
X
Y
X (m) X (m)
Y (
m)
Y (
m)
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RADAR DATA PROCESSING
GOAL ->Identify Proximate Events:
R
2 HConflict:Aircraft physical separation< intended margin (D, H)
Collision: Aircraft physical separation< aircraft physical sizes
Conflicts
Potential Conflicts
Potential Collisions
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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 SPOTS
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SAFETY METRICS ESTIMATION
Analysis of Proximate Events
Classification of Proximate Events
Detection of Activated Alert Systems
Identification of ATM System Weaknesses
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tCI
v1
v2
CPA(t cpa ,[r12]cpa,[h12]cpa)
t cpa : time at CPA
[r12]cpa: horizontal separation at CPA
[h12]cpa: vertical separation at CPA
[r12]cpa<R & [h12]cpa<H
tCI : time of identification of potential
conflict
SAFETY METRICS ESTIMATIONAnalysis of Proximate Events
CRIDA. CRM 3D. ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010) 11/10/2010 17
tCI
v1 *
v2
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 * <H
t m: time of maneuvre
Change in the Rate of Climb (ROC)
New CPA*(t* cpa ,[r12]*cpa,[h12]*cpa)
tm
SAFETY METRICS ESTIMATIONAnalysis of Proximate Events
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tCI
v1
v2
[h12]cpa : vertical separation at CPA
[h12]cpa >H
t m: time of a conflict resolution manoeuvretm tCR
Climb->Level
SAFETY METRICS ESTIMATIONAnalysis of Proximate Events
CRIDA. CRM 3D. ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010) 11/10/2010 19
tCI
H
r12: actual horizontal separation
h12: actual vertical separation
r12 <R & h12 =H
t m: time to entry into conflict volumetm tCF
SAFETY METRICS ESTIMATIONAnalysis of Proximate Events
CRIDA. CRM 3D. ENRI Int. Workshop on ATM/CNS. Tokyo, Japan. (EIWAC 2010) 11/10/2010 20
SAFETY METRICS ESTIMATION
NATUREVERTICAL REGIME
RELATIVE HEADING
A/C REACTIONTRAFFIC TYPE
Passing Event
PROXIMATE EVENT
Conflict
Potential Conflict
Level-Level (LL)
Climb-Level(CL)
Descend-Level(DL)
Climb-Climb(CC)
Climb-Descend(CD)
Descend-Descend(DD)
Same
Opposite
Crossing
Civil Traffic
Both Military Aircraft
One Military Aircraft
CRITERIA
Change Vertical Profile
Modify Heading
ACTIVATED ALERT SYSTEM
TCAS TA
STCA
TCAS RA
Change of Speed
No Alert No Reaction Potential Collision
False Detection
Classification of Proximate Events
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SAFETY METRICS ESTIMATION
[r12]CPA
tCI
Aircraft 2
Aircraft 1
tCF tCPA
tCI: identification of potential conflicttCR: start of a conflict resolution manoeuvretCF: predicted time of entry into conflict volumetCPA: predicted time of CPA[r12]cpa: horizontal separation at CPA
t2 :Time to Conflict
t3 :Time-to-go to CPA
R
Predicted trajectory
t1 : Overall Reaction Time
t1=tCR-tCI
t2=tCF-tCI
t3=tCPA-tCI
tCR
Detection of Activated Alert Systems
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SAFETY METRICS ESTIMATION
35 sec48 sec
2 mins4 mins
TIME TO CPA
Potential Collision
TCAS RA(See & Avoid,..)
TCAS TATACTICAL
Safety Barriers
35 sec48 sec2 mins4 mins
TIME TO CPA
( )P Tactical Failure
( )RiskP
( )P STCAFailure
( )P TCASTAFailure
( )P TCAS RAFailure
No lossof Sep.
No loss of Sep.
Loss ofSeparation?
Loss ofSeparation
Collision
Yes
No
Yes
No
Yes
No
Yes
No
STRATEGIC
Yes
No(Pre )P Tactical Failure
TACTICALBASED ON STCA
Detection of Activated Alert Systems
No lossof Sep.
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SAFETY METRICS ESTIMATION
VERTICAL CLOSURE RATE (fpm)
Strategic
ATC Action TacticalATC Action(STCA)
Traffic Advisory (TA)
35 sec
VE
RT
ICA
L S
EPA
RA
TIO
N (f
eet)
48 sec
2 min
H
850 600
ResolutionAdvisory (RA)
Detection of Activated Alert Systems
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SAFETY METRICS ESTIMATIONDetection of Activated Alert Systems
HORIZONTAL PLANE VERTICAL PLANE
-5 -4.5 -4 -3.5 -3 -2.5 -2
x 105
-1
-0.5
0
0.5
1
x 105
X
Y
204.0 kts
22.6 22.65 22.7 22.75 22.8 22.85 22.9 22.95 23 23.05
320
330
340
350
360
370
380
time (h)
Alt
itu
de
(F
L)
0.0 fpm
1875.0 fpm
RARA
Alt
itud
e(F
L)
Y
Time (h)
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Proximate Event Data: AC 1 - AC 2
[r12]cpa
(NM)
[h12]cpa
(ft)
TTC
(min)
Dur
(min)
TCPArel
ManoeuvreAC1
ManoeuvreAC2
Legend
T0 0.66 -0.00 5.99 0.001.67
-0.42 00.00 -5.12 -0.00
T1 0.24 0.00 0.86 -0.005.12
>Conv(85º)<
Turn 5.7º
TCAS RA
0.01 -0.00 -0.40 -0.00
T2 0.25 0.00 0.46 -0.000.40
AC1 Turn ; ><
CL FL
CONFLICT RESOLVED-VERTICAL PLANE
0.11 1000.00 -0.23 0.00
T3 0.36 1000.00 0.22 0.000.24
AC2 CL FL ; VER SEP; >Conv(88º)<
MIN REAL SEP: 0.3 NM 1000 ft
-0.01 00.00 -0.22 -0.03
T4 0.34 1000.00 0.00 -0.030.48
>Conv(93º)<
2.44 -0.00 0.00 0.29
T5 2.79 1000.00 0.00 0.260.80
<Div(99º)>
Tm
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0 100 200 300 400 500 600 700 800 9000
5
10
15
20
25
30
35
40
45
50
Horizontal Closure rate (kts)
Ho
rizo
nta
l D
ista
nce
(n
m)
Resolution Advisory
Traffic Advisory
Tactical ATC Action (STCA)
Strategic ATC Action
T0
T1
T3
T4
0 1000 2000 3000 4000 5000 60000
1000
2000
3000
4000
5000
6000
7000
8000
Vertical Closure Rate (fpm)
Ve
rtic
al S
ep
ara
tio
n (
ft)
Resolution Advisory
Traffic Advisory
Tactical ATC Action (STCA)
Strategic ATC Action
T1
T3T4
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 event in the horizontal plane and in the vertical plane are in the red area at the same time.
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SAFETY METRICS ESTIMATION
HAZARD(potential collision)
Traffic Density
+
Traffic complexity
+
ATC/Pilot Errors
+
Technical Failures
Initiating events leading
to potential collisions
Detection / Resolution of
potential collisions
ATCO STCA TCAS …
No Safety Effect
Conflict
Collision
Risk Context Qualification of HazardsEffectiveness of Safety
Barriers
Identification of ATM System Weaknesses
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SAFETY METRICS ESTIMATION
Risk Context (within
selected area/time-
frame)
Effectiveness of
Safety Barriers
Flight-Time Hot Spots Number of Real Conflicts
Number of MovementsClassification of Proximate
Events:
• Nature
• Traffic Type
• Vertical regime
• Relative heading
• A/C Reaction
• Activated Alert System
(TCAS, STCA)
Overall Reaction Time
Kinematics
(Speed, Type of Aircraft)Time Margin
Nº of Entries and Exits Time to Conflict
Route structure Time-to-go to the CPA
Traffic Density
% of Potential Conflicts
solved in:
• vertical plane and
• horizontal plane
Number of Routes
Correlation between
Hot Spots and
Traffic Density Maps.
Average Nº of Aircraft “near”
a Proximate Event
% Evolving (non-level) Aircraft Nº of potential collisions
Separation Rules
Qualification of Hazards
Identification of ATM System Weaknesses
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SAFETY METRICS ESTIMATION
Side Length=7.5 NM
Risk Context
(within selected
area/time-frame)
Identification of ATM System Weaknesses
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SAFETY METRICS ESTIMATION
Qualification of
Hazards
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3
4
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CIVIL-MILITARY TRAFFIC
MILITARY TRAFFIC
CIVIL TRAFFIC
Total Number of Proximate Events: 45389
CIVIL TRAFFIC 91.2%
MILITARY TRAFFIC 3.2%
CIVIL-MILITARY TRAFFIC 5.6%
Total Number of Proximate Events: 41397
POTENTIAL CONFLICT 84.86%
ACTUAL CONFLICT 0.08%
FALSE DETECTION 14.59%
PASSING EVENT 0.46%
LEVEL-LEVEL 13.8%
LEVEL-CLIMB 59.6%
LEVEL-DESCENT 7.1%
CLIMB-CLIMB 11.9%
CLIMB-DESCENT 6.4%
DESCENT-DESCENT 1.2%
Total Number of Proximate Events: 35166
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TCAS RA
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SAFETY METRICS ESTIMATION
Effectiveness of Safety Barriers
ATC STRATEGY 69.6%
STCA 28.0%
TCAS TA 2.1%
TCAS RA 0.3%
0 1 2 3 4 5 6 7 8 90
1
2
3
4
5
6
7
8
9
10
Overall Reaction Time (min)
Tim
e-t
o-g
o t
o t
he C
PA
(m
in)
0
10
20
30
40
50
60
70
80
90
0 1 2 3 4 5 6 7 8 9 100
100
200
300
400
500
600
700
800
900
Overall Reaction Time (t1)
Overall Reaction Time (min)
0 1 2 3 4 5 6 7 8 9 100
100
200
300
400
500
600
700
Time-to-go to CPA (t3)
Time-to-go to CPA (min)
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CONCLUSIONS
The 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 in depth assessment of proximate events:
Identification of all proximate events based on radar data.
Complete classification of all proximate events using clear and consistent criteria.
Detailed information on the evolution of each proximate event.
Safety metrics and other air traffic factors
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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-route to Terminal Manoeuvring Area (TMA) scenarios;
•Develop a methodology to provide a complete risk picture of the scenario, identifying the ATM system weakness and characterizing 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 safety levels in their operation;
•Complete an analytical model based on the 3-D CRM tool to provide true collision risk values.
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CRIDA (Centro de Referencia I+D+i ATM)
Questions