Transcript Slide 1

ACRP 4-09
Risk Assessment Method to
Support Modification of
Airfield Separation Standards
Period:
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Jun 2009 to Feb 2011
Developed by:
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Applied Research Associates, Inc.
Robert E. David & Associates
University of Oklahoma
Risk of Collision per Operation
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ADG V
1.E-03
ADG V Standard = 267 ft
1.E-04
1.E-05
1.E-06
1.E-07
1.E-08
1.E-09
222
224
226
228
230
232
234
Taxiway/Taxiway Centerline to Centerline Separation (ft)
236
Project Panel
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Chair
 Ms. Laurie Cullen – HNTB Corporation
ACRP Staff Representatives
 Ms. Marci A. Greenberger – Program Officer
 Mr. Joseph J. Brown-Snell – Program Associate
Members
 Mr. Gary C. Cathey - California Department of Transportation
 Mr. Chad A. Gunderson - TKDA
 Mr. Paul Herrera - Los Angeles World Airports
 Mr. Scott McMahon - Morristown Municipal Airport
 Jorge E. Panteli - MacFarland-Johnson
Liaison Representatives
 Mr. John Dermody - Federal Aviation Administration
 Mr. Chris Oswald - Airports Council International - North America
 Christine Gerencher – Transportation Research Board
Project Team
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Principal Investigator
 Jim Hall – Applied Research Associates
Co-Principal Investigator
 Richard Speir – Applied Research Associates
Project Manager
 Manuel Ayres – Applied Research Associates
Team Members
 Hamid Shirazi – Applied Research Associates
 Robert E. David – RED & Associates
 Yih-Ru Huang – University of Oklahoma
 Regis Carvalho – Applied Research Associates
 Arun Rao – Consultant
 Samuel Cardoso – Applied Research Associates
 Edith Arambula – Applied Research Associates
Briefing Outline
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Background
 Study Objectives
 Project Tasks
 Rationale of Airfield Separations
 Accident and Incident Data Collected
 Basis of Approach Used
 Risk-Based Analysis Methodology
 Case Studies and Validation
 Plan to Gain Industry Support
 Limitations and Conclusions
Background
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Many airports were built before current standards were set
There is a need to increase airport and aviation capacity,
and operation of larger aircraft may be required in existing
airfields
In many cases there are physical and environmental
restrictions to increase existing separations
Available analysis alternatives are prescriptive and not
based on risk
Approximately 20% of ground (commercial aviation)
accidents in the U.S. are collisions during taxiing or
parking
More than 50% of fatal accidents occur during landing and
takeoff operations
Modification of Standards (MOS)
AC 150/5300-13 (FAA, 1989)
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Modification to standards means any change to FAA
design standards other than dimensional standards for
runway safety areas.
Unique local conditions may require modification to
airport design standards for a specific airport.
The request for MOS should show that the
modification will provide an acceptable level of safety,
economy, durability, and workmanship.
Study Objectives
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Develop simple and easy to use methodology to
evaluate risk of collisions associated with nonstandard airfield separations.
Obtain quantitative assessment for decision making
when standard cannot be met.
The methodology should serve as a screening tool to
evaluate the feasibility of submitting to the FAA a
request for Modification of Standards.
Project Tasks
1.
2.
Literature review and rationale of airfield separations
Collection of veer-off accident and incident data
Modification of Standards (MOS) survey
4. Develop proposed risk assessment methodology
5. Perform airport survey for selected MOS cases
6. Develop risk assessment methodology
3.
7.
8.
Develop plan to gain industry support
Prepare project report
Rationale for Standards - FAA
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Taxiways and Taxilanes: probability distribution of lateral
deviations plus a safety buffer of 10 ft
 TWY/TWY: 1.2 x WS + 10 ft (between centerlines)
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TWY/OBJ: 0.7 x WS + 10 ft (axis to object)
TXL/TXL: 1.1 x WS + 10 ft (between centerlines)
TXL/OBJ: 0.6 x WS + 10 ft (axis to object)
Runways: probability distributions of lateral and vertical
deviations during final approach and initial climb, as well
as probability of veer-offs during landing and takeoff
Indication that standards were developed based on best
engineering judgment and experience from WW II
Rationale for Standards - ICAO
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Taxiway/Taxiway and Taxiway/Object:
 Wingtip Clearance = clearance (C) between the outer
main gear wheel and the taxiway edge plus safety
buffer (Z).
Runway/Taxiway
 Distance to accommodate potential veer-offs and provide
sterile area free of obstacles for aircraft executing a
missed approach or balked landing maneuver.
Veer-off Data Collection
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Veer-off accidents and incidents occurring in several
countries from 1980 to 2009
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Taxiway/Taxilane veer-offs
 Identified 300 incidents in straight segments of
taxiways
 Only 6 relevant incidents were identified in taxilanes
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Identified 679 runway veer-off accidents and incidents
during landing and takeoff
Taxiway Veer-offs – Some
Conclusions
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Taxiing airplanes are at lower speeds (normal 20
knots, max 30 knots) when compared to runway
operations.
The edge of the paved area is a discontinuity and the
pilot is able to stop as soon as the aircraft departs the
taxiway.
The model for lateral deviation can be truncated for
taxiways outside the ramp area.
The collisions occurred in curves or when other aircraft
and equipment were inside the taxiway/taxilane OFA.
Taxiway Veer-offs – More Conclusions
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Taxiway veer-offs in straight segments occured due to
poor visibility or low surface friction (e.g. Icing
conditions).
Two-part models based on frequency and location
were not appropriate for the methodology.
Only two fatal accidents due to taxiway veer-offs were
identified; neither was relevant to this study.
Basis of Approach Used
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Probability distributions of lateral and vertical
deviations during operations
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Boeing/FAA Taxiway Deviation Studies at ANC and
JFK (Scholz, 2003 and 2005)
Airborne risk during landing derived from Collision
Risk Model (CRM) runs
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Ground roll risk of veer-off derived from models
developed in this project (landing and takeoff)
Taxiways and Taxilanes Separation
Probability Distribution of Lateral Deviations
WS1
X
d = wingtip separation
d = CS – (WS1 + WS2) / 2
centerline separation (CS)
WS2
Taxiway or Taxilane to Object Separation
Probability Distribution of Lateral Deviations
aircraft semi wingspan
wingtip lateral
deviation probability
distribution
0
X
obstacle
RWY/TWY Separation
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Risk of collision during airborne phase
 Landing
Final Approach
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Missed Approach
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Rejected Landing
Takeoff – Initial Climb
Risk of collision during ground roll
 Landing
 Takeoff
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Deviations in Airborne Phase
x
Nominal Flight Path
(x = 0, y = 0)
Obstacle
y
h
Nominal Flight Path
x
Y1 = NFPh - h
Obstacle
y
X1 = XO – WS/2
h
Runway Veer-off
Landing (or Takeoff)
1
2
x
3
Risk-Based Analysis Methodology
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Taxiway to Taxiway or Taxilane
Taxiway to Object
Taxilane to Taxilane
Taxilane to Object
Runway to Taxiway/Taxilane/Object
 Landing
 Airborne
 Ground
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phase
rolling phase
Takeoff
 Ground
rolling phase
Taxiway Lateral Deviation Studies
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FAA/Boeing (Scholz, 2003 and 2005)
Collision risk models were developed by Boeing/FAA
based on B-747 taxiway deviation studies at ANC and
JFK
The objective was to evaluate the risk of collision for
B-747-800 operations
Data was collected during one year
In both cases, lateral deviation data was collected in
straight segments with taxiway centerline lights
Assumptions
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Lateral deviation for smaller aircraft are similar or
smaller than those of the B-747
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The taxiway or taxilane centerline is conspicuous and
visible to the pilot under any operational conditions
The FAA separation standards for taxiways and
taxilanes are based on similar probability of aircraft
departing the lane during taxiing operations
The risk estimated with the CRM is more restrictive
compared to the risk under visual conditions
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ACRP 4-09 Methodology
Example of Risk Plot for Taxiway/Taxiway Separation – ADG
I
ADG I
1.E-05
Risk of Collision per Operation
ADG I Standard = 69 ft
1.E-06
8.0E-7
1.E-07
1.E-08
1.E-09
62
64
66
68
70
Taxiway/Taxiway Centerline Separation (ft)
72
Lateral Deviation Models for
Taxilanes
Wingtip
Separation
Taxiway/Object
Taxilane/Object
Ratio
I
20
15
0.75
ADG - Distances in ft
II
III
IV
V
26
34
44
53
18
22
27
31
0.69 0.65 0.61 0.58
VI
62
36
0.58
Taxilane
Similar Probability
Taxiway
Analysis Procedure
Taxiways/ Taxilanes/Objects
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Identify the type of separation
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Identify the ADG or aircraft types involved
 Characterize the separation (between centerlines,
between centerline and object, or wingtip clearance)
 Identify the appropriate risk plot to use
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Use the centerline or wingtip clearance to estimate risk
of collision
Example - Taxiway/Taxiway
Separation
Taxiway/Taxiway Separation - ADG V
Risk of Collision per Operation
1.E-05
ADG V Standard = 267 ft
1.E-06
1.E-07
2.3E-08
1.E-08
1.E-09
226
228
230
232
234
Taxiway/Taxiway Centerline to Centerline Separation (ft)
236
Risk Analysis during Landing
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Airborne Phase
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Ground Roll Phase
Collision Risk Model (CRM) Runs
Development of Risk Curves
Airborne Phase
ADG III - CAT I
-328 ft
0 ft
1500 ft
1.0E-08
3000
ft
4500 ft
1.0E-09
1.0E-12
1.0E-15
0
100
200
300
400
500
Aircraft Distance from Runway Centerline (ft)
Risk of Collision per Operation.
Risk per Operation
1.0E-06
600
ADG III - CAT I
ADG III Approach Cat C
Standard = 400 ft
1.0E-09
700
1.0E-10
1.0E-11
200
250
300
350
400
Runway/Taxiway Centerline Separation (ft)
450
500
Runway Veer-off Incident Rates (U.S.)
(1980-2009)
Number
Type of
of
Incident
Incidents
LDVO
512
TOVO
111
Incident Rate
per Operation
1.195E-06
2.590E-07
Incident Rate in
Operations per
Incident
837,000
3,861,000
Location Model – Landing Veer-off
Prob=exp((-.02568)*Y**(.803946))
R2=99.5%
Probability of Stopping Beyond Y
1.0
0.8
0.6
0.4
0.2
0.0
0
200
400
600
Distance Y from Runway Edge (ft)
800
1000
Analysis Procedure – Runway/Taxiway
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Identify the ADG
Identify type of approach (Cat I or Cat II)
Characterize the separation between the runway and
taxiway axes
Identify plots for specific ADG (landing)
 Airborne phase (lateral and vertical deviations)
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Ground roll phase (frequency and location)
Use axes separation to estimate risk of collision for
each phase
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Repeat process for takeoffs
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Risk Criteria – FAA Risk Matrix
Risk estimated is compared to risk criteria to check for acceptability
Case Studies and Validation
Airp.
ADG
Type of MOS
Risk
Level
Expected #
Yrs
Risk <
1.0E-7
Risk <
1.0E-09
Credible
Severity
FAA Risk
Classification
Acceptable
PHL
ANC
ADS
BDR
III, IV
VI
III
II
Taxilane/Taxilane
Taxiway/Object
Runway/Taxiway
Runway/Taxiway
<1.0E-9
<1.0E-9
1.0E-7
1.1E-7
N/A
N/A
> 100
> 100
Yes
Yes
Yes
No
Yes
Yes
No
No
Major
Major
Catastrophic
Catastrophic
Low
Low
Medium
Medium
Yes
Yes
Yes
Yes
MFV
N07
JFK
EWR
II
I
VI
V
MSP
ORD
ORD
HYA
LCI
SEA
SEA
ASE
ACK
ILG
JYO
TAN
IV
V
V
III
III
VI
VI
III
III
IV
II
II
Runway/Object
Taxilane/Object
Taxiway/Taxiway
Taxiway/Taxiway
Taxilane/Object
Taxiway/Taxiway
Taxiway/Object
Taxiway/Taxiway
Runway/Taxiway
Runway/Taxiway
Runway/Taxiway
Taxiway/Taxilane
Runway/Taxiway
Taxiway/Taxiway
Taxiway/Object
Runway/Taxiway
Runway/Taxiway
5.9E-8
1.2E-9
<1.0E-9
<1.0E-9
<1.0E-9
<1.0E-9
<1.0E-9
<1.0E-9
8.8E-8
2.0E-7
1.6E-6
<1.0E-9
9.0E-8
<1.0E-9
2.8E-8
1.2E-7
8.0E-8
> 100
N/A
N/A
N/A
N/A
N/A
> 100
> 100
N/A
N/A
> 100
N/A
> 100
> 100
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
No
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
No
Yes
No
No
No
Catastrophic
Major
Major
Major
Major
Major
Major
Major
Catastrophic
Catastrophic
Catastrophic
Major
Catastrophic
Major
Major
Catastrophic
Catastrophic
Medium
Low
Low
Low
Low
Low
Low
Low
Medium
Medium
High*
Low
Medium
Low
Low
Medium
Medium
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No*
Yes
Yes
Yes
Yes
Yes
Yes
Plan to Gain Industry Support
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Research Product
 Risk assessment methodology to evaluate airfield
separations and intended to serve as a screening tool to
support the submittal of MOS for FAA approval
 Audience
 Civil aviation agencies like the FAA, ICAO, military
aviation organizations, and civil aviation stakeholders
 Main obstacle for implementation
 Will require FAA support
 Implementation
 Actions to present the product in airport conferences
and aviation safety meetings (TRB, AAAE, ACC, ACI)
 Presentation to the FAA Office of Airports
Limitations
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Can only be used to assess risk for straight parallel
segments of taxiways and taxilanes.
 Taxiway deviations for smaller aircraft were assumed
to be equal or smaller than deviations for the Boeing
747 aircraft.
 Application of the models for taxiway and taxilane
deviations assume the centerline is conspicuous under
any weather and light conditions.
 Veer-off models were developed based on incidents
and accidents of aircraft with MTOW larger than 5,600
lbs.
 Assumed the lateral and vertical deviation probability
distributions provided by the Collision Risk Model is
conservative when considering visual conditions.
Conclusions
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The methodology developed in this research study
provides a practical and simple guide to help airports
quantify and evaluate risk associated with nonstandard airfield separations.
 The risk assessment obtained can be helpful to
examine the feasibility of and to support MOS requests
to the FAA.
 The methodology is based on lateral and vertical
deviation studies and models developed in this
research as well as in previous studies conducted by
the FAA, Boeing, and ICAO.
 The methodology was validated using twenty MOS
cases approved by the FAA.