landing in conf 3 – use of reversers
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Landing in CONF 3 – Use of reversers
Hélène REBELHead of A330/A340 Operational Standard
Presented by:
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General considerations
Airbus Flight Crew Operating Manuals recommendation
Maximize safety margins
CONF FULL – Maximum Reverse thrust
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General considerations
• Above all, the first considerations must be:
The aircraft landing weightThe runway lengthThe braking meansThe runway surface conditionsThe tailwindAutoland not certified in CONF 3 (CONF 15/20) for A300/A310
aircraft family
• For economics, airlines could envisage:Approach in CONF 3Idle or no reverse thrust at landing
All operational and economics consequences have to be considered.
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Content
General considerations
Fuel economy estimation
Additional considerations:
Other operating cost considerations
Operational consequences
Pro and Cons: Summary
Conclusion
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Fuel economy estimation
• Depends on several parameters as:
– Aircraft / Engine type– Aircraft weight during the approach– Approach speed– Autobrake selection– Airport elevation– The ISA conditions– …
Fuel economy estimation
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Fuel economy estimation
• Simulation hypothesis
Airport elevation: Sea LevelISA conditionsApproach speed VLS + 5 knotsAutobrake LO2 aircraft weights: light and heavy weights
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Fuel economy estimation
• Simulation hypothesis – Cont’d
1500 ft:
S/F configuration for landing: CONF 3 or FULL
REV IDLE
LANDING AT REV IDLE
0 kt
1500 ft:
S/F configuration for landing: CONF 3 or FULL
IDLE THRUST
LANDING WITH NO REV
0 kt
1500 ft:
S/F configuration for landing: CONF 3 or FULL
70 kts *
REV IDLEREV MAX
LANDING AT REV MAX
0 kt
* 85 kts for Wide Body aircraft
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Fuel economy estimation
• RESULTSAverage fuel consumption increase in kg
betweenREV MAX
and
REV IDLE
REV IDLE and
No REV
CONF FULL
and
CONF 3
CONF FULL / REV MAX
and
CONF 3 / REV IDLE
A320
family
10 to 1510 to 15
15 to 2015 to 20
22
22
10 to 1510 to 15
5 to 155 to 15
15 to 3015 to 30
20 to 4020 to 40
A330
family
25 to 4525 to 45
40 to 6040 to 60
55
55
10 to 1510 to 15
10 to 2510 to 25
40 to 5540 to 55
60 to 7560 to 75
A340-200/300
3535
4040
55
55
1515
15 to 2015 to 20
5050
6060
A340-500/600
6565
85 to 9085 to 90
1010
1515
1010
55
7575
9595
A300
family
30 to 4030 to 40
50 to 6550 to 65
33
33
15 to 2515 to 25
15 to 3015 to 30
5050
8080
Light weightLight weight
Heavy weightHeavy weight
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Content
General considerations
Fuel economy estimation
Additional considerations:
Other operating cost considerations
Operational consequences
Pro and Cons: Summary
Conclusion
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Other operating cost considerations
Direct Maintenance Cost (DMC) is mainly affected by thermal cycling or age of the materials
Deployment of reversers has a minor impact in DMC
• Thrust Reversers
Lower reversers thrust Reduction of FOD risk and associated maintenance
No advantage to do a landing without reversers
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Other operating costs consideration
Tire wear is affected by several parameters which are mainly:– Loads
– Pressure
– Ground surface roughness
– Temperature
– Aircraft roll
If basic braking recommendations are applied:Overall tire DMC impact is likely to be small
Straight line rolling:
20% to 30%Maneuvering :
10% to 20%Touch down:
20% to 30%
Braking:
20% to 40%
•Tires
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Other operating costs consideration
• Brakes
Braking Energy (106 J / wheel)REV MAX REV IDLE No REV
CONF FULL
(30/40)
99
1818
1414
2727
1818
3333
CONF 3
(15/20)
1010
2020
1515
3333
2020
4040
Increasing the approach speed and/or using Rev Idle will lead higher brake temperature
Example of brake energy difference depending on the approach speed and the use of reverse : A300-622
Autobrake LO
Slightincrease
Multiplied by 1.5Multiplied by 2
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Other operating costs consideration
• Brakes
In general carbon brake life is affected by
– Carbon brake wear
– Carbon brake oxidation• Catalytic oxidation
• Thermal oxidation
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Other operating costs consideration
Carbon brake wear is mainly affected by:
– Number of brake applications
Not linked to the approach conf or the use of reversers
• Brakes: Effect on Carbon Brake wear
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Other operating costs consideration
– The brake temperature
Messier - Bugatti
Honeywell-ALS
BF Goodrich
0
Wear rate
80Indicated temperatureC
250150 315 500
Optimum brake temperature range is still compatible with such operations
• Brakes: Effect on Carbon Brake wear
Carbon brake wear is mainly affected by:
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Other operating costs consideration
Thermal oxidation is temperature and time related:
– Repetitive high temperature occurrences– Long duration of carbon exposure to high temperature
• Brakes: Effect on Carbon Brake thermal oxidation
Thermal oxidation leads to severe brake damage (disk rupture, etc) or loss in braking efficiency
Premature brakes removal
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Other operating costs consideration
Increased approach speed Higher brake energy is necessary to stop the aircraft
Rev Idle instead of Rev max Poor sharing of brake energy between reversers and brakes
Depending on flight crew braking management, brake oxidation could be drastically increased
• Brakes: Effect on Carbon Brake thermal oxidation
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Other operating costs consideration
To minimize negative effect on the brakes the following could be considered:
– Restrict the application of such procedure to runway where Autobrake LO can be used and is actually used.
– Do not override the autobrake to shorten the landing distance.
– Respect basic Airbus SOP recommendations:
• Delay the brake fans selection for 5 minutes (or at the gate) if turn-around permits.
• Avoid prolonged parking brake application on hot brakes.
• Brakes: General guidelines
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Content
General considerations
Fuel economy estimation
Additional considerations:
Other operating cost considerations
Operational consequences
Pro and Cons: Summary
Conclusion
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Operational consequences
• Approach in CONF 3:
Higher pitch attitude
May increase the number of alert triggering by the Flight Data Monitoring software
Impact on tailstrike margins
–Tailstrike margins are reduced (except for the A321 aircraft) but, for example, roughly corresponds to:
– 5 to 6 degrees on Single Aisle Aircraft family– 7 to 8 degrees on Long Range Aircraft family
Tailstrike margins remain comfortable
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Operational consequences
Potential increase in runway occupancy time and block time
Additional brake cooling time: could be limitative in case of short turn around-time
Must be taken into account for operations
• Use of reversers at Idle:
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Content
General considerations
Fuel economy estimation
Additional considerations:
Other operating cost considerations
Operational consequences
Pro and Cons: Summary
Conclusion
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Pro and Cons: Summary
Landing in CONF 3
Use of Idle reverse thrust
Tires DMC
Thrust reversers DMC
Tailstrike margins
Brake wear
Brake oxidation
Brake cooling time
Runway occupancy time
• The economics vary a lot from one airline to another but pro and cons can be summarized as follows:
Fuel economy
Noise reduction
FOD
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Content
General considerations
Fuel economy estimation
Additional considerations:
Other operating cost considerations
Operational consequences
Pro and Cons: Summary
Conclusion
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Conclusion
– Airbus recommendation is:
• To maximize safety margins in normal operation, Airbus SOP still recommends to approach in CONF FULL and to use MAX thrust reverse for landing.
• For economics, provided runway length and conditions are favorable, landing in CONF 3 and/or use of idle reverse thrust can be considered.
• No REV landing not recommendedSystem Safety Assessment based on the fact that reversers are
deployed at each landingNo real benefit in term of fuel economy
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Conclusion
• When applying such procedure, to minimize induced negative effect, the following could be considered:
• Restrict the application of such procedure on runway where Autobrake LO can be used and check dispatch conditions.
• Do not override the autobrake to shorten the landing distance
• Pay particular attention on brake fans useGood Dispatcher and Flight Crew awareness is necessaryGood Dispatcher and Flight Crew awareness is necessary
Clear Airline policy has to be defined for:Clear Airline policy has to be defined for:- All aircraft typesAll aircraft types- All considered runwaysAll considered runways
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