Understanding FL CH in FCOM 2
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Joined: Apr 2008
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From: Test
Understanding FL CH in FCOM 2
Hi,
Pertaining to Go-Around and having selected FL CH after acceleration height on climb to a certain altitude.
1) How does the system know when to change to climb thrust having gone around and selected FL CH after acceleration height?
Pertaining to Go-Around and having selected FL CH after acceleration height on climb to a certain altitude.
1) How does the system know when to change to climb thrust having gone around and selected FL CH after acceleration height?
Last edited by extricate; 9th March 2018 at 16:16.
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Joined: Apr 2008
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From: Test
For B777.
This pertains to go-around. Assuming I went around with Toga (Pressed once), 1000ft, i'll start accelerating by winding up the speed and cleaning up the aircraft accordingly. Once flaps are up, when I press FL CH, thrust will change from GA to CLB. How does the system know when to change to CLB? Is it by flaps settings? As per takeoff sequence?
This pertains to go-around. Assuming I went around with Toga (Pressed once), 1000ft, i'll start accelerating by winding up the speed and cleaning up the aircraft accordingly. Once flaps are up, when I press FL CH, thrust will change from GA to CLB. How does the system know when to change to CLB? Is it by flaps settings? As per takeoff sequence?
Joined: Oct 2006
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From: N/a
The thrust is scheduled by the Autothrottle/ Thrust mode logic.
When you push the TO/GA buttons, the Autothrottle engages in ‘GA’ mode, in this mode, the first push of the buttons gives reduced go around thrust to achieve 1000-2000fpm. The second push gives full go around thrust.
Engaging level change during a climb, causes the Autothrottle mode to change to ‘N1’. The N1 mode is programmed to schedule CLB thrust.
When you push the TO/GA buttons, the Autothrottle engages in ‘GA’ mode, in this mode, the first push of the buttons gives reduced go around thrust to achieve 1000-2000fpm. The second push gives full go around thrust.
Engaging level change during a climb, causes the Autothrottle mode to change to ‘N1’. The N1 mode is programmed to schedule CLB thrust.
Joined: Feb 2001
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From: The Winchester
For B777.
This pertains to go-around. Assuming I went around with Toga (Pressed once), 1000ft, i'll start accelerating by winding up the speed and cleaning up the aircraft accordingly. Once flaps are up, when I press FL CH, thrust will change from GA to CLB. How does the system know when to change to CLB? Is it by flaps settings? As per takeoff sequence?
This pertains to go-around. Assuming I went around with Toga (Pressed once), 1000ft, i'll start accelerating by winding up the speed and cleaning up the aircraft accordingly. Once flaps are up, when I press FL CH, thrust will change from GA to CLB. How does the system know when to change to CLB? Is it by flaps settings? As per takeoff sequence?
In your scenario above AA you are now simply asking the system to perform a “standard” FLCH climb where the thrust is metered to try and get you to the required altitude (as set in the MCP) in two minutes...or if it can’t achieve that rate of climb because of the magnitude of the climb the auto thrust will set full climb thrust.
I’m pretty sure the flap position is irrelevant....
Last edited by wiggy; 10th March 2018 at 05:33.
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Joined: Apr 2008
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From: Test
What other thrust setting would you think would be appropriate given you have selected FLCH and have deliberately taken the thrust and pitch part of the autoflight system out of go around mode?
In your scenario above AA you are now simply asking the system to perform a “standard” FLCH climb where the thrust is metered to try and get you to the required altitude (as set in the MCP) in two minutes...or if it can’t achieve that rate of climb because of the magnitude of the climb the auto thrust will set full climb thrust.
I’m pretty sure the flap position is irrelevant....
In your scenario above AA you are now simply asking the system to perform a “standard” FLCH climb where the thrust is metered to try and get you to the required altitude (as set in the MCP) in two minutes...or if it can’t achieve that rate of climb because of the magnitude of the climb the auto thrust will set full climb thrust.
I’m pretty sure the flap position is irrelevant....
