Why do business aircraft go off the runway more often than commercial aircraft?

Why do business aircraft go off the runway more often than commercial aircraft?

Gerard van Es

58th annual Business Aviation Safety Seminar

Montreal, Canada

April, 2013

What is a runway excursion?What is a runway excursion?

2

A veeroff or overrun off the

runway surface during takeoff or landing

Do business aircraft go off the runway more often? Do business aircraft go off the runway more often?

3

0

0.5

1

1.5

2

2.5

3

3.5

4

Y2010 Y2011 Y2012

Business

Commercial

Runway excursion rate per million flights

Worldwide data, accidents & incidents

Source: NLR-ATSI

Business

Commercial

0 0.5 1 1.5 2 2.5

ICAO Annex 13 Accident Rate1980-2008

Rate per million flights

Runway excursion accident rateRunway excursion accident rate

4

Difference is getti

ng smaller la

st 5 yrs

Source: NLR-ATSI

Is runway excursion risk importantfor business aviation?Is runway excursion risk importantfor business aviation?

35% of all take-off & landing accidents with business ops involved a runway excursion;

Can result in fatalities and/or significant damage to a/c;

In top 6 of NTSB Priorities on Business Aviation safety.

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Some accident/incident data analysisSome accident/incident data analysis

Source: NLR-ATSI Air Safety Database

Inclusion criteria:

– Runway excursions with known causes;

– Period 1980-2010;

– Worldwide;

– Single engine aircraft excluded;

– Turbine/turboprop aircraft.

>1600 excursions met these criteria.

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Flight phase and excursion typeFlight phase and excursion type

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Type Phase Business Commercial

Aircraft overrun Landing 38% 39%

Aircraft overrun Take-off 10% 12%

Veeroff Landing 36% 39%

Veeroff Take-off 16% 10%

Source: NLR-ATSI

Top factors in runway excursionsTop factors in runway excursions

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0% 5% 10% 15% 20% 25% 30% 35% 40% 45%

High on approach

Hard land

Abort/reject - After V1

Aquaplaning

Tire failure

Incorrect use of stopping devices

Tailwind

System failure

Crosswind

Fast approach/TD

Long flare

wet/contaminted rwy

Commercial

Business

Percentage of all excursions with known factors

Exposure to risk factorsExposure to risk factors

Similar distribution of top causal factors between business and commercial operations;

Difference in exposure to risk factors?

– Knowledge of day to day operations needed;

– Based on FDM/FOQA data;

– Focus on landing.

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Wet/contaminated runway operationsWet/contaminated runway operations

Reduction runway friction;

No good data on number of business operations on wet/contaminated runways;

Business a/c can operate at smaller airports:

• Runway surface condition monitoring less sophisticated;

• Less equipment for snow removal.

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Unstabilised approachesUnstabilised approaches

Influence on fast & high approaches;

Comparison typical rates:

– Commercial operations: 1-8% of all approaches;

– Business operations: 1-14% of all approaches;

Go-around rates following unstabilised approaches are low:

– Only 1-2 % of unstabilised approaches resulted in a go-around;

– Higher values in commercial ops.

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Source: NLR-ATSI/FSF

Fast approachesFast approaches

Speed difference at threshold (VTH – Vapp )>15 kts;

3-5 times more likely on business a/c operations.

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Source: NLR-ATSI

Long flare (long landing, deep landing)Long flare (long landing, deep landing)

Rate of landings >2,400 ft touchdown from threshold

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Commercial

Business

0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20%

Source: NLR-ATSI

8 Times more likely on business ops

-20 ─ -15

-15 ─ -10

-10 ─ -5

-5 ─ 0

0 ─ 5

5 ─ 10

10 ─ 15

15 ─ 20

20 ─ 25

25 ─ 30

30 ─ 35

0%

5%

10%

15%

20%

25%

30%

35%

CommercialBusiness

Tailwind operationsTailwind operations

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Headwind Kt.Tailwind Kt.

More tailwind landings in business ops

Source: NLR-ATSI/FSF

Runway length in overruns occurrencesRunway length in overruns occurrences

15

LA-Business

LA-Passenger/cargo

TO-Business

TO-Passenger/cargo

0 500 1000 1500 2000 2500 3000

Average runway length (m)

A/c type depended

No data on day-to-day ops

Source: NLR-ATSI

Landing distance assessmentLanding distance assessment

Issues with landing distance assessments at time of arrival:

– Not always required by operator (dispatch assessment only);

– Confusion on whether reverse thrust has been included;

– Sometimes based on (un)factored AFM instead of realistic landing performance data;

– No (good) data for contaminated runways;

– No guidance on how to use actual operational landing distance information;

– No safety factors applied. 16

Runway width in veeroffs occurrencesRunway width in veeroffs occurrences

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Business

Commercial

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

Average runway width (m)

Matches with runways normally used

Source: NLR-ATSI

Wheel track comparisonWheel track comparison

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Commercial a/c

5-14 m

Business a/c

2.5-6 m

Maximum allowable deviation from centerline is 9.1 m;

VMCG and X-wind adjustments could be needed on narrow rwys (not common on business a/c).

Demonstrated crosswinds (dry rwy)Demonstrated crosswinds (dry rwy)

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1950 1960 1970 1980 1990 2000 2010 20200

5

10

15

20

25

30

35

40

45

50 Business JetsPassenger aircraft

Year of certification

Cros

swin

d (k

ts)

Buss Jets average: 26 kts

Passenger a/c average: 30 kts.

Source: NLR-ATSI

Crosswind and contaminated runwaysCrosswind and contaminated runways

Not part of certification – advisory only;

Advisory material normally available for commercial a/c:

– But not perfect!

Often limited advisory material for business a/c, e.g.:

– Only for an icy runway;

– Statements like “extreme care should be taken...”, no hard numbers;

– Crosswind limits based on non-validated correlation with runway friction coefficient.

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How to manage the risk?How to manage the risk?

Check out the different initiatives and tools, e.g.:

European Action Plan for the Prevention of Runway Excursions (EAPPRE);

IATA/FSF Runway Excursion Risk Reduction (RERR) Toolkit;

FSF - Runway Excursion Risk Awareness Tool:

– Can be used during dispatch.

FSF - ALAR toolkit;

Guidance material from NBAA.

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Remember there is more than factorcausing runway excursions Remember there is more than factorcausing runway excursions

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Excess approach speed,

Late touchdown,

Delayed application wheel brakes.

Example

ConclusionsConclusions

Runway excursion causes are the same for business and commercial aircraft;

Exposure to certain risk factors is often higher during business operations:

– Unstabilised approaches;– Long landings;– Fast landings;– High tailwind landings.

Less guidance for operations on contaminated runways for business a/c;

Lack of FDM/FOQA data for business operations (less awareness of rwy excursion risk factors).

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It can happen more than once....It can happen more than once....

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SANTOS DUMONT AIRPORT, Brazil

Landing overrun

Take-off overrun