Is the problem in the pilot or in the A/P?

1

So when i put vs a/p on it pulls the nose radically up or down. Why?

2

this is known issue on A321 and 777 300ER I guess…

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3

Because you don’t have the plane trimmed properly. Eliminate the purple in the trim box prior to engaging. Soley pilot error.

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4

All planes that i have flyed

5

ok… but personally only have issue on A321 and 777 300ER
and it’s confirmed

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6

To answer the question. Pilot.

When you turn on AP, you naeed to make sure the the aircraft is trimmed. Most plots see this after taking off and are climbing at +3000 VS and then turn on AP the nose will pitch down violently.

Now if you are saying that at cruise altitude your nose moves up and down, that is a known issue. Compound that with being overweight and/or high/low speed and it can make it worse.

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7

That’s a first not sure why you would need the vector indicator near the horizoon bar to get a smooth A/P engagement. Since that only happens at higher speed.

8

Sorry I adjusted my comment. It plays into it but is more of a symptom of not being trimmed like you said.

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9

is there any app thing to say how much trim is needed?

10

I already told you it’s a feel not a calculation.

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11

but you can’t get the trim right on ground if don’t do some mystical calculations

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12

You don’t need to get it right on the ground. you perfect it in the air. I start out with 15% on most aircraft. Except the spit which I do -15% and the MD which is closer to 50-60%.

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13

Keep in mind, aircraft load % plays a factor in how much trim is/will be needed.

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14

I have fiund it is around 23% for the B777s as that is what you would need to adjust it to that at cruise if you kept it at 15% on climb

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15

yea i know thats why i was thinking that there could be some calculator that calculates the trim when weight is … and plane is … so you need …% trim

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16

MD-11’s as well I usually have to adjust ap twice.

17

oh yeah? I have flew them quite many times…
Haven’t experienced yet…Thanks for report tho

18

It’s all I fly now. I used to change it up, but whether it’s the commercial version or freighter I simply just no longer find much interest in flying anything else. I know our beloved if provides a multitude of liveries and models but I have found that as certainly proves true in real life no takeoff, route, pattern, approach, or landings can ever be routine, the same. I can wheel the 11 like a fighter when I am truly just having fun or like the behometh freight mover and passenger carrier she was designed and built to be. God I’m all giddy just talking about it!!!

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19

i have the same problem :D @Douglas_Chanley

20

Here’s a basic guide for using elevator trim

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