takeoff performance
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takeoff performance
Anyone can help me , what is the maximum sum of clearway + stopway for the use in takeoff performance calculations ?
Is this s.th about 1.5 times TORA ???
Thanks
Is this s.th about 1.5 times TORA ???
Thanks
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(a) I'm not aware of any hard standards on maximum stopway/clearway lengths (perhaps one of our airports engineering specialists may care to offer some expertise on this point ?) but guidance is provided in documents such as FAA AC 150/5300-13 which suggests a practical clearway limit of 300m at pp23.
(b) From the point of view of a particular aircraft, the maximum clearway able to be scheduled is determined by the TORR and TODR. Depending on the rules applying, a proportion of the airborne distance from liftoff to screen (usually one-half) is required to be scheduled over the physical TORA declared for the runway. This, naturally enough, is very desirable to give the aircraft some chance of getting off the ground before the end of the smooth bit .....
If the takeoff is TOR-limited, the provision of excessive clearway is unusable and of no scheduling use for the operator ... all clear area, however, is gratefully appreciated ...
(b) From the point of view of a particular aircraft, the maximum clearway able to be scheduled is determined by the TORR and TODR. Depending on the rules applying, a proportion of the airborne distance from liftoff to screen (usually one-half) is required to be scheduled over the physical TORA declared for the runway. This, naturally enough, is very desirable to give the aircraft some chance of getting off the ground before the end of the smooth bit .....
If the takeoff is TOR-limited, the provision of excessive clearway is unusable and of no scheduling use for the operator ... all clear area, however, is gratefully appreciated ...
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Do you mean this?
ICAO Annex 14 Para 3.5.2,
Recommendation.- The length of a clearway should not exceed half the length of the take-off run available.
I don't know of any limitation on stopway length.
ICAO Annex 14 Para 3.5.2,
Recommendation.- The length of a clearway should not exceed half the length of the take-off run available.
I don't know of any limitation on stopway length.
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According my training (JAR OPS) the following for transport category aircraft applies:
Stopway - can be used only to determine Accelerate Stop Distance. This allows for much higher TOM and V1.
Clearway - can be used only to a small extent for T/O calculation. It is not allowed to calculate the T/O Performance using the Stopway. So one of the two is limiting.
I am not aware of any limitation of clearway or stopway lenght. E.g. consider a runway leading out on the sea so the clearway is more or less unlimited.
Nevertheless the rules allow only the use of a max clearway lenght of 1/2 the runway lenght. This means: You have to Take Off at a Mass allowing to climb one engine inop to 35 ft in the distance: Rwy length + (1/2 Rwy lenght if unlimited clearway) or available clearway lenght. So for this you are right with 1.5 RWY lenght. But - careful with TORA, because:
more fun rules apply for clearway use. From point of Lift off OEI to 35 ft 1/2 of the distance has to be over the runway.
From this you can calculate the balanced Performance trading off ASD vs. TODR to get the max TOM allowed to fulfill all restrictions.
That's why a loooooong runway is always best.
FAR and JAR describe this in the Part 25 (Take-off). In FAR 25.113(a) and followings.
Now: How to calculate this when taking of e.g. LSZH on RWY 28 with an A321 at Max TOM? You don't. Simply pick the AOM and look it up in the Runway tables provided for the various RWY's usually used by the operator and get the figures from OAT and Mass.
Other Calculations on unknown places: Call your dispatch and have them calculate it on their computers... or spend 2 hours doing it on your own from the AOM.
Get the Information for FAR 25.113 here:
http://www.airweb.faa.gov/Regulatory...e?OpenFrameSet
JAR-OPS are for purchase only
[url]http://www.jaa.nl/catalogue/catalogue.html#para14[url]
Stopway - can be used only to determine Accelerate Stop Distance. This allows for much higher TOM and V1.
Clearway - can be used only to a small extent for T/O calculation. It is not allowed to calculate the T/O Performance using the Stopway. So one of the two is limiting.
I am not aware of any limitation of clearway or stopway lenght. E.g. consider a runway leading out on the sea so the clearway is more or less unlimited.
Nevertheless the rules allow only the use of a max clearway lenght of 1/2 the runway lenght. This means: You have to Take Off at a Mass allowing to climb one engine inop to 35 ft in the distance: Rwy length + (1/2 Rwy lenght if unlimited clearway) or available clearway lenght. So for this you are right with 1.5 RWY lenght. But - careful with TORA, because:
more fun rules apply for clearway use. From point of Lift off OEI to 35 ft 1/2 of the distance has to be over the runway.
From this you can calculate the balanced Performance trading off ASD vs. TODR to get the max TOM allowed to fulfill all restrictions.
That's why a loooooong runway is always best.
FAR and JAR describe this in the Part 25 (Take-off). In FAR 25.113(a) and followings.
Now: How to calculate this when taking of e.g. LSZH on RWY 28 with an A321 at Max TOM? You don't. Simply pick the AOM and look it up in the Runway tables provided for the various RWY's usually used by the operator and get the figures from OAT and Mass.
Other Calculations on unknown places: Call your dispatch and have them calculate it on their computers... or spend 2 hours doing it on your own from the AOM.
Get the Information for FAR 25.113 here:
http://www.airweb.faa.gov/Regulatory...e?OpenFrameSet
JAR-OPS are for purchase only
[url]http://www.jaa.nl/catalogue/catalogue.html#para14[url]
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There are two more possibilities. Most manufacturers restrict the clearway that can be used to well below the ICAO limit so that the take-off calculation must be TODA limiting and can not under any circumstance become TORA limiting. This keeps the complexity of the graphs down by considering only one 'go' limit, the TODA. The L1011 graphs showed 'max allowable clearway' for this purpose.
Second possibility is you are referring to the B737 which assumes TORA=TODA=ASDA for its 'normal' take-off calculation and then allows V1 to be modified according to the amount left when you subtract stopway from clearway. There is a maximum allowable clearway associated with this table which I believe derives from the argument above.
Second possibility is you are referring to the B737 which assumes TORA=TODA=ASDA for its 'normal' take-off calculation and then allows V1 to be modified according to the amount left when you subtract stopway from clearway. There is a maximum allowable clearway associated with this table which I believe derives from the argument above.
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error401,It's generally understood that the 'clearway' case applies mainly in the 4eng GO case(all eng T/O +15% case to the screen).
The 2 eng (one eng out at Vef reject)acc/stop distance really uses the Stopway.
Keeping in mind the 'rules' require Half the Distance to the screen be'smooth'bits(over the runway)consider the 'actual' height over the end of the Runway when taking off WET and going for the screen of 15' at the end of a 1000'clearway(JAA rules)....8/9feet???
The 2 eng (one eng out at Vef reject)acc/stop distance really uses the Stopway.
Keeping in mind the 'rules' require Half the Distance to the screen be'smooth'bits(over the runway)consider the 'actual' height over the end of the Runway when taking off WET and going for the screen of 15' at the end of a 1000'clearway(JAA rules)....8/9feet???
