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?

2

A veeroff or overrun off the

runway surface during takeoff or landing

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 rate

4

Difference is getting sm

aller last 5 yrs

Source: NLR-ATSI

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.

5

Some 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 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 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

CommercialBusiness

Percentage of all excursions with known factors

Exposure 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 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 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. 11

Source: NLR-ATSI/FSF

Fast 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)

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 ─ 1010 ─ 1515 ─ 2020 ─ 2525 ─ 3030 ─ 35

0%

5%

10%

15%

20%

25%

30%

35%

CommercialBusiness

Tailwind operations

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Headwind Kt.Tailwind Kt.

More tailwind landings in business ops

Source: NLR-ATSI/FSF

Runway length in overruns occurrences

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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 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.

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Runway 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 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)

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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 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?

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. 21

Remember there is more than factorcausing runway excursions

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Excess approach speed, Late touchdown, Delayed application wheel brakes.

Example

Conclusions

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....

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SANTOS DUMONT AIRPORT, Brazil

Landing overrun

Take-off overrun