I’m not too familiar with flying Boeing aircraft . But in terms of trimming the aircraft I know that is done when there is a speed change however is there still a need to do so if the A/T can maintain the speed for us ?
B787 Trim Operation
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A350Cadet -
November 28, 2024 at 4:19 PM -
Thread is Resolved
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- Official Post
The 777 and 787 are fly by wire aircraft where pitch trim inputs adjust the trimmed airspeed during flight. Trimming nose down increases the internal target airspeed and the aircraft will have a simulated natural tendency to fly towards that airspeed.
The manuals are not very clear as to what happens if you fly with auto-throttle engaged and use pitch trim inputs. Currently we don't simulate any cross-talking between auto-throttle target speed and fly-by-wire target trim speed. This means if the auto-throttle is controlling for speed by throttle adjustments and the fly-by-wire is controlling for speed by pitch adjustments this can escalate towards either full climb thrust or full idle thrust. It's not stable long term. If you fly with flight directors on, auto-throttle in CLB or IDLE then your fly by wire pitch trim still controls the airspeed as usual. So ideally you then fly with auto-throttle off or, you need to find the sweet spot where the fly-by-wire trim speed matches the auto-throttle target airspeed.
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The 777 and 787 are fly by wire aircraft where pitch trim inputs adjust the trimmed airspeed during flight. Trimming nose down increases the internal target airspeed and the aircraft will have a simulated natural tendency to fly towards that airspeed.
The manuals are not very clear as to what happens if you fly with auto-throttle engaged and use pitch trim inputs. Currently we don't simulate any cross-talking between auto-throttle target speed and fly-by-wire target trim speed. This means if the auto-throttle is controlling for speed by throttle adjustments and the fly-by-wire is controlling for speed by pitch adjustments this can escalate towards either full climb thrust or full idle thrust. It's not stable long term. If you fly with flight directors on, auto-throttle in CLB or IDLE then your fly by wire pitch trim still controls the airspeed as usual. So ideally you then fly with auto-throttle off or, you need to find the sweet spot where the fly-by-wire trim speed matches the auto-throttle target airspeed.
If I’m using mobile though , how would I know if I’m off trim ?
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- Official Post
On mobile the assistance for auto-trim is also active per default which means its trimming for you.
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On mobile the assistance for auto-trim is also active per default which means its trimming for you.
So I can’t trim it myself on mobile ?😭
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So I can’t trim it myself on mobile ?😭
Yurp found out the hard way in my case
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Yurp found out the hard way in my case
What’s was the hard way of finding out 😭
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What’s was the hard way of finding out 😭
Doing it mid flight and it doesnt stop triming
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Luckily I was in a boeing 737 so wasnt as bad... wink wink
