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Performance oncontaminated runways
-Friction Coefficient - Crosswind - Use of FCOM
Operations Liaison Meeting
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2Performance on contaminated runways - Friction coefficient - Crosswind - Use of FCOM
Content
Runway condition: Airport information Correlation airport information/FCOM data
FCOM data
Performance determination
Crosswind
Conclusion
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A SNOWTAM contains :
The type of contaminants,
Mean depth for each third of the runway length,
Estimated braking action,
Reported Mu ()(Friction coefficient)
Reported Mu Estimated
Braking Action
0.4 and above GOOD
0.39 to 0.36MEDIUM/GOOD
0.35 to 0.30 MEDIUM
0.29 to 0.26
MEDIUM/POOR
0.25 and below POOR
Runway condition: Airport information
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Airbus charts are provided by type of contaminants
and the depth of contaminant on the runway.1/4 and 1/2 inch of slush, 1/4 and 1/2 inch of water, compacted snow
A linear relation has been established between loose snow and slush,
Sometimes, only the Estimated braking action orReported Mu is available.
Is it possible to get the performance from a given reported Mu?
Runway condition: Airport information
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Airports release a friction coefficient derived from
a measuring vehicle. This friction coefficient is
termed as reported Mu
The actual friction coefficient, termed as effectiveMu (or aircraft Mu) is the result of the interaction
tire/runway.
It depends on the tire pressure, tire wear, aircraftspeed, aircraft weight and anti-skid system efficiency.
Correlation airport information/FCOM dataEffective mu and reported mu
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Measuring vehicles operate at much smaller weight
and speed than aircraft.
Tests have demonstrated that there is a poor
correlationbetween the reported Mu and theeffective Mu. There is even a poor correlation in
between the measuring vehicles.
Even with an ideal reported Mu equals to the
Effective Mu the type and depth of contaminants
would be necessary.
Correlation airport information/FCOM dataEffective mu and reported mu
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There is a clearseparation in the effect of contaminants on
the aircraft performance in hard and fluid contaminants
Hard contaminants are : Compacted snow and ice
Fluid contaminants are : Water, slush and loose snow.
Hard: Decrease of friction forces
Fluid: Decrease of friction forces +
precipitation drag and aquaplaning
Correlation airport information/FCOM dataHard and fluid contaminants
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Precipitation drag The precipitation drag is composed of : Displacement drag
produced by the displacement of the contaminant fluid from the path of
the tire.
Spray impingement drag
produced by the spray thrown up by the wheels (mainly those of thenose gear) onto the fuselage.
The effect of these additional drags must be
accounted for:
They affect the deceleration performance: positive effect.
They affect the acceleration performance: negative effect.
The effect on the acceleration leads to a limitation
in the depth of fluid contaminants on the runway.
Correlation airport information/FCOM data
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Aquaplaning The presence of a fluid contaminant on the runway creates
an intervening film between the tire and the runway
leading to a reduction of the dry contact area.
It gets more critical at higher speeds where the fluid
cannot be squeezed out from between the tire and therunway.
Aquaplaning is a situation where the tire of the aircraft are
to a large extend separated from the runway surface.
Friction forces drop to almost negligible values.
Directional control and braking are virtually
ineffective.
Correlation airport information/FCOM data
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Airbus does not provide the take-off and landingperformance on contaminated runways according to
the reported braking action or to a reported .
Aircraft performance on a fluid contaminated runway
depends on the effective and the depth of fluid onthe runway.
Charts are provided for: 1/4 inch water, 1/2 inch water, 1/4 inch slush, 1/2 inch slush.
Aircraft performance on a hard contaminated runwaydepends on the effective .Charts are provided for: compacted snow (=0.2) and icy runway (=0.05)
Correlation airport information/FCOM dataSummary
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FCOM data
Runway Conditions:
Dry / Damp
Wet
Contaminated
Different Contaminants:
Standing Water
Slush
Wet Snow
Dry Snow
Compacted Snow
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FCOM data
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FCOM data
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FCOM data
Standing water:
3 mm: wet
> 3 mm: contaminated
Different Contaminants - Standing Water
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FCOM dataDifferent Contaminants - Slush
Slush:
2 mm: wet> 2 mm: contaminated
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FCOM dataDifferent Contaminants - Wet snow
Wet snow:
4 mm: wet> 4 mm: contaminated
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FCOM dataDifferent Contaminants - Dry snow
Dry snow:
15 mm: wet> 15 mm: contaminated
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WET or CONTAMINATED?
15 mm: wet
4 mm: wet 2 mm: wet 3 mm: wet
Dry SnowWet SnowSlushStanding Water
FCOM dataDifferent Contaminants - Summary
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In case of a wet
runway use:
WET runway corrections
FCOM data
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In case of a contami-
nated runway: Standing Water > 3 mm:
depth 3 mm ~ 6.3 mm
depth 6.3 mm ~ 12.7 mm
Slush > 2 mm:
depth 2 mm ~ 6.3 mm
depth 6.3 mm ~ 12.7 mm
FCOM data
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In case of a contaminated runway:
Wet Snow > 4 mm:
12.7 mm (1/2 inch) wet snow isequivalent to 6.3 mm (1/4 inch)
slush.
Dry Snow > 15 mm:50.8 mm (2 inches) dry snow is
equivalent to 6.3 mm (1/4 inch)
slush.
Compacted Snow:
12.7 mm6.3 mm=
Wet Snow Slush
50.8 mm
6.3 mm=
Dry Snow Slush
FCOM data
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15 mm
4 mm2 mm3 mm
Dry SnowWet SnowSlushStanding Water
any depth
Compacted Snow
12.7 mm 12.7 mm
25.4 mm
6.3 mm 6.3 mm
12.7 mm
50.8 mm
Wet runway corrections
15 mm
4 mm2 mm3 mm
FCOM data - Summary
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Dry SnowWet SnowSlushStanding Water
any depth
Compacted Snow
12.7 mm
25.4 mm
6.3 mm
12.7 mm
50.8 mm
15 mm
4 mm2 mm3 mm
Contaminated
runway corrections
12.7 mm
6.3 mm
FCOM data - Summary
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Dry SnowWet SnowSlushStanding Water
any depth
Compacted Snow
12.7 mm 12.7 mm
25.4 mm
6.3 mm
15 mm
4 mm2 mm3 mm
Contaminated
runway corrections
6.3 mm
12.7 mm
50.8 mm
FCOM data - Summary
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Dry SnowWet SnowSlushStanding Water
any depth
Compacted Snow
12.7 mm
6.3 mm 6.3 mm
12.7 mm
50.8 mm
15 mm
4 mm2 mm3 mm
12.7 mm
25.4 mm
Contaminatedrunway corrections
FCOM data - Summary
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Dry SnowWet SnowSlushStanding Water Compacted Snow
12.7 mm 12.7 mm
25.4 mm
6.3 mm 6.3 mm
12.7 mm
50.8 mm
15 mm
4 mm2 mm3 mm
Contaminatedrunway corrections
any depth
FCOM data - Summary
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Dry SnowWet SnowSlushStanding Water
any depth
Compacted Snow
12.7 mm 12.7 mm
25.4 mm
6.3 mm 6.3 mm
12.7 mm
50.8 mm
15 mm
4 mm2 mm3 mm
FCOM data - Summary
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Performance determination Landing: refer to FCOM tables
Takeoff: Different methods are available depending on each
airlines
The level of conservatism or details and difficulty
depends on the method
Takeoff chart DRY + FCOM correction
Takeoff chart DRY + takeoff chart correction(OCTOPUS: A319, A321, A330, A340)
Takeoff chart CONTAMINATED
Less Paper Cockpit program (LPC)
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FCOM:
Landing distances
Performance determination - Landing
For all runway conditions
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Takeoff chart DRY + FCOM correction
- Takeoff chart DRY
Performance determination - Takeoff
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Performance determination - TakeoffTakeoff chart DRY + FCOM correction
- FCOM corrections
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Performance determination - Takeoff Takeoff chart DRY + Takeoff chart correction
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Performance determination - Takeoff Takeoff chart CONTAMINATED
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Performance determination - Takeoff Less Paper Cockpit (LPC) program
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Airport : Airbus City, runway 31
OAT = 5oC, No wind, Standard QNH
Runway covered with 5 mm slush
Performance determination - TakeoffExample: A330-223
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245.9 3/6
159/62/67
Performance determination - TakeoffTakeoff chart DRY + FCOM correction
- Takeoff chart DRY
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Takeoff chart DRY +
FCOM correction- FCOM corrections
Performance determination - Takeoff
24.8
MTOW DRY 245.9Correction - 24.8
Corrected Weight 221.1
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Performance determination - Takeoff
MTOW DRY 245.9
Correction - 24.8Corrected Weight 221.1
Takeoff chart DRY +
FCOM correction- FCOM corrections
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Takeoff chart DRY+ Takeoff chart
correction
Performance determination - Takeoff245.9 3/6
159/62/67
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Performance determination - Takeoff
MTOWDRY
245.9
Correction - 23.2
MTOW1/4 SLUSH
222.7
Takeoff chart DRY+ Takeoff chart
correction
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225.0 3/3
142/52/55
Performance determination - TakeoffTakeoff chart CONTAMINATED (Slush 1/4)
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Performance determination - Takeoff Less Paper Cockpit (LPC) program
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Performance determination - Takeoff Less Paper Cockpit (LPC) program
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Performance determination - Takeoff Less Paper Cockpit (LPC) program
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A330-223
Airport : Airbus City, runway 31
OAT = 5oC, No wind, Standard QNH
Runway covered with 5 mm slush
Performance determination - Takeoff
Takeoff chart
DRY + FCOM
correction
Takeoff chart
DRY + chart
correction
Takeoff chart
SLUSH(*)
LPC
program
221.1 t 222.7 t 225 t 225 t
Method
Takeoff
weight
Difficulty
of use
Summary
(*) If max TO weight SLUSH > max TO weight DRY, take max TO weight DRY
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CrosswindDemonstrated crosswind
A demonstrated crosswind is given in the FCOM Demonstrated : Maximum crosswind which was
experienced during the flight test campaign.
Applicable fordry and wet runways.
Demonstrated crosswind is not a limitation.
This is an information providing an indication of what
was experienced during flight test to give some
guidance for operators to establish their own
limitations.
FAR/JAR 25 requires this information to be given.
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Crosswind
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Crosswind on contaminated runways
A poor runway friction coefficient affects both
braking actionanddirectional control and thus
the capability to sustain high crosswinds fortakeoff and landing
Airbus has issued some recommendations based
on calculation and operational experience
Crosswind
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CrosswindCrosswind on
contaminatedrunways
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Conclusion On wet and contaminated runways it is mandatory
to get the type and depth of contaminant Reported runway friction coefficient (Mu) and estimated
braking action are of no use to determine takeoff and
landing performance
Several tools and methods exist to determinetakeoff performance
When operating regularly on contaminated
runways it is recommended to publish takeoff
charts for the associated contaminant