2010 FAA Worldwide Airport Technology Transfer Conference2010 FAA Worldwide Airport Technology Transfer Conference Risk Assessment of RSA Alternatives at San Risk Assessment of RSA Alternatives at San Francisco International AirportFrancisco International Airport

Manuel AyresRegis CarvalhoMichael LawrenceHamid ShiraziRichard SpeirEdith Arambula

Expanding the Realm of Possibility

OutlineOutline

Objective RSA Alternatives ACRP Methodology Analysis with EMAS SFO Scenarios Results Conclusions

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ObjectiveObjective

Present Case-Study for probability assessment of aircraft overruns and undershoots in support of cost-benefit studies to select infrastructure alternatives for existing SFO RSAs, including the use of Engineered Materials Arrestor Systems (EMAS).

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Alternatives to Improve RSAsAlternatives to Improve RSAs

Extend existing RSA Modify or relocate the runway Implemente declared distances Use arresting systems (e.g. EMAS)

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ACRP MethodologyACRP Methodology

ACRP Report 3 – Analysis of Aircraft Overruns and Undershoots for Runway Safety Areas

Methodology for quantitative assessment of Runway Safety Areas

http://onlinepubs.trb.org/onlinepubs/acrp/acrp_rpt_003.pdf

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Model StructureModel StructureThree-Part Risk Model

Eventprobability

Locationprobability

Accidentconsequences Risk

Operatingconditions

Operating conditions, terrain

Location probability,

obstacle location, size and type, aircraft type

High

Medium

Low

High

Medium

Low

High

Medium

Low

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ACRP Report 3ACRP Report 3 Approach to quantitatively estimate the probability that an aircraft

will exit the runway and stop beyond a given distance from the runway end

mbyeyLocationP }{

x

y

naxexLocationP }{

RSA

Stop LocationProbability Distribution

y

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Frequency ModelsFrequency Models

Probability = Ni/a / Nn (under certain operation conditions)

P{Event} is the probability (0-100%) of an accident type occur given certain operational conditions.

Xi = f(ceiling, visibility, crosswind, gusts, rain, type of aircraft, etc.)

...33221101

1}{

XbXbXbbeEventP

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A Simple ExampleA Simple Example

0

1

Risk Factor (e.g. x-wind)

Prob

abili

ty o

f Eve

nt (e

.g. L

DO

R)

XW1 XW2

Possible cut-off points

P1

P2

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Location ModelsLocation Models

Distance x from runway end

Pro

babi

lity

loca

tion

Exc

eeds

x

x1

P{Loc > x1}

naxexLocationP }{

Xrwy end

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Location Model - ExampleLocation Model - Example

Raw Distances Model for Landing Overruns

0%

20%

40%

60%

80%

100%

0 500 1000 1500 2000 2500

Distance x from Threshold

Pro

b{di

stan

ce >

x

) %

Actual Raw DistancesRaw Distances Model

P{d>x}=exp(-0.003871*x^0.955175)R2=99.8%; n=257

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Analysis with EMAS – Basic ConceptAnalysis with EMAS – Basic Concept

L RSA

-EM

AS

x1

x2

a)

EMAS

Regular Terrain

L RSA

-EQ

x1

RLF·x2

b)

Regular Terrain

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Analysis with EMASAnalysis with EMAS

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50Reported max speed entering EMAS bed (m/s)

Pred

icte

d m

ax s

peed

ent

erin

g EM

AS

bed

(m/s

)

SWv log1482.31log8329.60057.3

EMASEMASRSA

EMASRSA SRLFS

aa

S

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Aircraft MovementsAircraft MovementsArrival

End/RSALDOR LDUS TOOR Total # of

Movements Challenging the RSA

19R 17 3,864 75,728 79,60919L 101 17,660 138,738 156,49901R 17,660 101 294 18,05501L 3,864 17 1,355 5,23628R 433 189,570 12,160 202,16328L 251 131,294 11,809 143,35410R 131,294 251 51,806 183,35110L 189,570 433 49,322 239,325

Total 343,190 343,190 341,212 1,027,592

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Existing Conditions – Rwys 01/19Existing Conditions – Rwys 01/19

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SFO RSA AlternativesSFO RSA Alternatives Refinement A

Bay fill to install standard EMAS on 19s Shift 1R/19L north

Refinement B Create standard RSAs for 28s

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Refinement ARefinement A

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Average Probability for all Movements (Existing) 1.41E-07Total Airport Probability if Complying w/ Standard 7.48E-08  Refinement ARSA 01R 01L 19R 19LTotal Airport Probability 1.08E-07RSA Contribution to Airport Probability Decrease -0.5% 0.1% 9.3% 14.7%% Protection Relative to FAA Standard 23.6%   Refinement BRSA 10R 10L 28R 28LTotal Airport Probability 1.12E-07RSA Contribution to Airport Probability Decrease 0.0% 0.0% 13.8% 6.4%Total % Decrease (all RSAs combined) 66.6%

Level of Protection for Refinement A + Refinement B 94%

Summary of ResultsSummary of Results

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Impact of Runway Shift on Total Airport ProbabilityImpact of Runway Shift on Total Airport Probability

RWY 01R/19L

15.0%

16.0%

17.0%

18.0%

19.0%

20.0%

156 206 256 340RWY Shift to South (ft)

Impr

ovem

ent i

n To

tal A

irpor

t Pr

obab

ility

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Impact of Rwy 01R/19L ShiftImpact of Rwy 01R/19L Shift

Percent Ops Subject to Prob > 1/1,000,000

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 100 200 300 400

Runway Shift (ft)

Acc

um P

roba

bilit

y (%

) 19L01R

0%10%20%30%40%50%60%70%80%90%100%

010002000300040005000600070008000

Freq

uenc

y

Probability Interval

RSA 01R - Total

Frequency

Cumulative %

0%10%20%30%40%50%60%70%80%90%100%

010000200003000040000500006000070000

Freq

uenc

y

Probability Interval

RSA 19L - Total

Frequency

Cumulative %

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Thank You!