Chamonix
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Boeing Trim:Wheels Vs Lever

Fri Dec 02, 2011 8:43 am

Why does the B739 still have trim wheels whilst the other Boeings have a lever?
Are there no picth trim switches on B739 yokes?
What are those odd looking 3 "toothpicks/fork-teeth" selectors on the B739 yokes.
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?
Many thanks!
 
yeelep
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RE: Boeing Trim:Wheels Vs Lever

Fri Dec 02, 2011 12:53 pm

Quoting Chamonix (Thread starter):
Why does the B739 still have trim wheels whilst the other Boeings have a lever?
Are there no picth trim switches on B739 yokes?

All 737's have a direct mechanical link from the trim wheels to the stabilizer jackscrew. The wheels are there to provide the means to physically move the stab. The 737 also has a electrically driven trim actuator controlled by trim switches on the outboard side of each control wheel. I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

Quoting Chamonix (Thread starter):
What are those odd looking 3 "toothpicks/fork-teeth" selectors on the B739 yokes.

Its a customer option, the altitude clearance reminder. Think of a combination lock that doesn't do anything.


Quoting Chamonix (Thread starter):
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?

From a quick look at some flight deck pictures, it looks like you may be mistaking the parking brake lever for the horizontal trim switches which appear to be the two black switches just inboard of that lever. Keep in mind that I have no knowledge of 787 systems, so I may be wrong.
 
David L
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RE: Boeing Trim:Wheels Vs Lever

Fri Dec 02, 2011 1:04 pm

I hope these will help...

739 (left) and 738 (right):


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Photo © Andre Klass
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Photo © Alexander Tarasenkov - St.Petersburg Spotters




788:


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Photo © Sam Chui

 
David L
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RE: Boeing Trim:Wheels Vs Lever

Fri Dec 02, 2011 1:12 pm

Quoting yeelep (Reply 1):
I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

I included the 738 to show that the trim wheels are not unique to the 739 but I came to the same conclusion that clean-sheet designs that came after the 737 didn't have the trim wheels. Unable to say why, I left it alone.  
 
tdscanuck
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RE: Boeing Trim:Wheels Vs Lever

Fri Dec 02, 2011 1:56 pm

Quoting Chamonix (Thread starter):
Why does the B739 still have trim wheels whilst the other Boeings have a lever?

Commonality to other 737's.

Quoting Chamonix (Thread starter):
Are there no picth trim switches on B739 yokes?

They're still there.

Quoting Chamonix (Thread starter):
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?

It's what yeelep said:

Quoting yeelep (Reply 1):
From a quick look at some flight deck pictures, it looks like you may be mistaking the parking brake lever for the horizontal trim switches which appear to be the two black switches just inboard of that lever. Keep in mind that I have no knowledge of 787 systems, so I may be wrong.

Just aft of the captain's touchpad is a silver lever and a wide black switch. The lever is the parking brake, the wide black switch is really two switches side by side to control trim. The two red guarded switches just inboard of that are the stab trim cutouts.

Quoting yeelep (Reply 1):
I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

Yes. It's not always electric by there's always some kind of dual path control and actuation for redundancy.

Tom.
 
barney captain
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 04, 2011 8:49 pm

Quoting David L (Reply 2):
Its a customer option, the altitude clearance reminder.

Fairly certain their intended purpose is for the current flight number - not altitude clearance.
Southeast Of Disorder
 
David L
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 04, 2011 8:58 pm

Quoting Barney Captain (Reply 5):

You might be right but, on the other hand and taking a variety of factors into consideration... it wasn't actually me who said it.

  
 
oldtimer
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 04, 2011 9:32 pm

Quoting Barney Captain (Reply 5):
Fairly certain their intended purpose is for the current flight number - not altitude clearance.

Was always the altitude reminder on my 707, 727 and 737 courses.

oldtimer
Oldtimer, I should have known better!
 
barney captain
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 05, 2011 8:47 am

Quoting David L (Reply 6):
You might be right but, on the other hand and taking a variety of factors into consideration... it wasn't actually me who said it.

Sorry about that....not sure what happened.

Quoting oldtimer (Reply 7):
Was always the altitude reminder on my 707, 727 and 737 courses.

Over 20 years flying Boeing's and I can honestly say, that's the first I've ever heard of this. Isn't that what the altitude window in MCP is for (or ALT Alerter going back to the classics)?

We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?
Southeast Of Disorder
 
oldtimer
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 05, 2011 10:17 am

Quoting Barney Captain (Reply 8):
We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?

Yes, the same thing was fitted to BAC1-11 and again was used as altitude reminder. You have to remember this goes back to pre INS and GPS days, these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold. You are only a sprog young man, pilots had to really work for a living in those days  
Oldtimer, I should have known better!
 
barney captain
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 05, 2011 7:04 pm

Quoting oldtimer (Reply 9):
these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold.

True - just like we always did in the -200's. But we still had an Altitude Alerter for that purpose.

Quoting oldtimer (Reply 9):
You are only a sprog young man, pilots had to really work for a living in those days

Awe shucks, and here I thought those 14 hour/12 leg days hand flying a Metroliner were all for fun  
Southeast Of Disorder
 
mandala499
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 4:32 am

And the wideblack trim switches on the pedestal is also not unique to the 787s...

Here's one from the 767-400:

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Photo © Daniel Piotrowski



So, new cockpit designs after 777 don't have the Trim Tabs?

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
Chamonix
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 12:29 pm

Amazing as ever,mandala499!
Never ever seen a Boeing w/o a ALT Pitch lever!
That is really weird!
So 767 does not have it,777 does,787 does not!
I can not figure out what that that tiny lever is behind the touchpad on the 787 next to Trim Tabs?
http://cdn-www.airliners.net/aviation-photos/photos/3/5/1/1942153.jpg
Maybe someone has a better pic?
 
David L
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 1:22 pm

Quoting Chamonix (Reply 12):
I can not figure out what that that tiny lever is behind the touchpad on the 787 next to Trim Tabs?

Do you mean this one...

Quoting tdscanuck (Reply 4):
Just aft of the captain's touchpad is a silver lever and a wide black switch. The lever is the parking brake,
 
tdscanuck
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 2:22 pm

Quoting Chamonix (Reply 12):
Never ever seen a Boeing w/o a ALT Pitch lever!
That is really weird!
So 767 does not have it,777 does,787 does not!

It's basically chronologic. The original 767's have pitch trim levers:

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Photo © Richard Barsby - Aviation Photographer
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Photo © Jorge Meneses



Then they developed the 777 and the levers are still there:

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Photo © Ken Iwelumo - Global Aviation Images
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Photo © Hannes Schauer



Then they did the 767-400ER and the levers disappeared from all versions of the 767 (not sure if by SB for the older models) and became the wide switches:

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Photo © Ryan Gaddis - Spot This!
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Photo © Charlie W Carter (EGTESkyGod)



The 787 kept going and stuck with the wide switches.

Tom.
 
Chamonix
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 2:37 pm

 
Chamonix
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 2:49 pm

Digressing onto the MD-11:Does it have 2 Flap selectors next to F/O?
http://flyawaysimulation.com/media/i...images/pmdg-md11-fsx-review-35.jpg (click to expand)
A380:Can anyone pinpoint where exactly are the new electronic tabs that have replaced the wheels on the Flightdeck?
 
mandala499
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 4:58 pm

Good catch by Tom...
It seems that all BA/exBA 763s originally came with the twin trim switches at the pedestal in place of the trim tabs...

Here is one from over 10 yrs ago!

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Photo © Matthew R N Clarkson


Interesting that they had the paddle CMD switches a la 747!

I guess they retrofitted the paddle switches to the button switches for the exBA 767-336s that went to Qantas... and also the PFD/EADI received the new format... whilst the BA one, stayed as it is!

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Photo © Wingnut



What is interesting is that BA 757s have both the trim tab version, and the wide trim switches version!


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Photo © Emil Almestad
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Photo © Mike Moores

Quoting Chamonix (Reply 15):
CWS/CMD have been blanked-out.

CWS mode was always an option, therefore, some/most, prefer to blank it out.

Quoting Chamonix (Reply 16):
Digressing onto the MD-11:Does it have 2 Flap selectors next to F/O?

It is remnant of the old days when slats and flaps were two separate levers... one of the reason is that, that was the norm in those days, and also for the crew to not make a mistake whether they're on a Slats equipped jet or not (DC-8s didn't have them, and some of the DC-9s didn't have them)... Here's a no-slat DC-9...

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Photo © Julian Whitelaw



And in the end, both the slats and flap lever were fused as one, but with two selectors... and you get:

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Photo © Roberto Leiro - SVZM Spotters



So, when they went to the DC-10... they went with a mechanical link like the DC-9...

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Photo © Europix - AirTeamImages



And some had it detached (or can have it attached or detached by choice?... need some DC-10 drivers to give better info...)

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Photo © David Watkins 82



So when they went to make the MD-11, they still kept that slot, and it's used for "Dial-a-Flap"... well, Wilco737... are you reading this???

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
Chamonix
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 6:23 pm

Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?
 
tdscanuck
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 06, 2011 9:02 pm

Quoting Chamonix (Reply 18):
Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?

I'm not really following you here...the lever/switch/wheel discussion (so far) has been all about stabilizer trim. That had nothing to do with the Spanair crash. I'm not aware of any large jet that doesn't use some kind of lever for flaps.

Tom.
 
PGNCS
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RE: Boeing Trim:Wheels Vs Lever

Sat Dec 10, 2011 12:56 am

Quoting oldtimer (Reply 7):
Quoting Barney Captain (Reply 5):
Fairly certain their intended purpose is for the current flight number - not altitude clearance.

Was always the altitude reminder on my 707, 727 and 737 courses.

Oh yes, the REALLY old days before altitude alerters were required. (Don't feel bad, I remember them too!)

Quoting Barney Captain (Reply 8):
Quoting oldtimer (Reply 7):
Was always the altitude reminder on my 707, 727 and 737 courses.

Over 20 years flying Boeing's and I can honestly say, that's the first I've ever heard of this. Isn't that what the altitude window in MCP is for (or ALT Alerter going back to the classics)?

We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?

Ah, but not all B-727 and DC-9's (and I believe B-737's as well, but I don't recall flying one without it installed) originally came with altitude alerters, and many even came with the dreaded three-pointer altimeter! (And yes, you are talking about the same thing.)  
Quoting Barney Captain (Reply 10):
Quoting oldtimer (Reply 9):
these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold.

True - just like we always did in the -200's. But we still had an Altitude Alerter for that purpose.

Oh I hated that autopilot (SP-77, I believe) and remember it well.

Quoting mandala499 (Reply 17):
Quoting Chamonix (Reply 15):
CWS/CMD have been blanked-out.

CWS mode was always an option, therefore, some/most, prefer to blank it out.

Yes, and even when installed few people bother with it as the Boeings in CWS are a pretty unharmonious and unpleasant experience.

Quoting Chamonix (Reply 18):
Which is better and easier to use:Levers or Wide Tabs?

They aren't ever used in normal operation, and I don't think in my simulator experiences there is a particular advantage to either.

Quoting Chamonix (Reply 18):

Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?

I'm confused. What does the Spanair accident have to do with stab trim switches?
 
mandala499
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RE: Boeing Trim:Wheels Vs Lever

Sat Dec 10, 2011 5:53 am

Quoting PGNCS (Reply 20):
Oh I hated that autopilot (SP-77, I believe) and remember it well.

SP-77 Mode 1... Lovely piece of engineering !    We call it, the "kitchen stove".
It really is a "point and hold" kind of automation... not the "press and forget" types...
But then... it hand flies beautifully, who needs CWS? (Well, CWS for the roll, hand flying for pitch"    )

*OK, I'm asking for you and Pihero to throw a rotted-away 732 AFM at me!*

Mandala499
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PGNCS
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 11, 2011 1:21 am

Quoting mandala499 (Reply 21):
SP-77 Mode 1... Lovely piece of engineering ! We call it, the "kitchen stove".

I laughed so hard I came out of Normal law!  
Quoting mandala499 (Reply 21):
It really is a "point and hold" kind of automation.

Wait! It's automation? Seriously?

Quoting mandala499 (Reply 21):
But then... it hand flies beautifully, who needs CWS? (Well, CWS for the roll, hand flying for pitch" )

I will say that the 732 is nicer to hand fly than some other Boeings, still not nearly as nice as the 757 though. It's sure easy to land, too. It's kind of like flying a big Cessna only not nearly as comfortable, ergonomic, or automated!
 
Chamonix
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 11, 2011 8:51 am

Quoting PGNCS (Reply 22):
I will say that the 732 is nicer to hand fly than some other Boeings

My Father-In-Law says his favourite of all times in terms of handling is the B727-200 ADV.
 
mandala499
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 11, 2011 6:06 pm

Quoting PGNCS (Reply 22):
I laughed so hard I came out of Normal law!

It's no joke that they use that term for the SP-77 here!   

Quoting PGNCS (Reply 22):
Wait! It's automation? Seriously?

Sorry, it's "non critical phase workload reducing apparatus"... Since it can be quite useless on critical phases!
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
PGNCS
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RE: Boeing Trim:Wheels Vs Lever

Sun Dec 11, 2011 8:57 pm

Quoting mandala499 (Reply 24):
Quoting PGNCS (Reply 22):
Wait! It's automation? Seriously?

Sorry, it's "non critical phase workload reducing apparatus"... Since it can be quite useless on critical phases!

OK, that's much better!  

I will certainly believe it's a NCPWRA (or a Kitchen Stove!) before I'll believe it's an autopilot!
 
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Francoflier
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 12, 2011 8:24 pm

I still don't like Boeing dropping the trim wheel.

There's nothing like the precision of a trim wheel when hand flying.
Of course, we're not really supposed to hand fly anything these days, but I've never gotten the hang of using a trim switch which, at least on earlier generation Boeings, provides no feedback and feels like it's connected to the stabilizer through an 18th century yarn spinner...

For hand flying, there's nothing like a big old trim wheel.
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
PGNCS
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 12, 2011 9:25 pm

Quoting francoflier (Reply 26):
For hand flying, there's nothing like a big old trim wheel.

There's also nothing like it for finger and knee injuries.  
 
Pihero
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 12, 2011 10:56 pm

Quoting PGNCS (Reply 27):

There's also nothing like it for finger and knee injuries.

especially when one had forgotten to retract the handle !

Quoting francoflier (Reply 26):

For hand flying, there's nothing like a big old trim wheel.

doesn't hold a candle to the best ever solution : The Tristar electric trim thumb wheel, seen here :

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Photo © Mark Abbott


Note that the manual wheel is still there.
Contrail designer
 
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tb727
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 12, 2011 11:14 pm

Quoting PGNCS (Reply 27):
There's also nothing like it for finger and knee injuries.

Remember, it will whack you in the knee 3 times before you can say ouch!
Too lazy to work, too scared to steal!
 
Pihero
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RE: Boeing Trim:Wheels Vs Lever

Mon Dec 12, 2011 11:14 pm

Quoting Chamonix (Reply 23):

My Father-In-Law says his favourite of all times in terms of handling is the B727-200 ADV.

Must have been drinking more than usual, that dear man: The 727 has never been an easy airplane and in terms of control balance.... it wasn't there with the best.
In fact I had a long chat with him and his favourite was the 744.

[Edited 2011-12-12 15:48:05]
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PGNCS
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 13, 2011 2:28 am

Quoting Pihero (Reply 28):
Quoting PGNCS (Reply 27):

There's also nothing like it for finger and knee injuries.

especially when one had forgotten to retract the handle !

YOW! I just got knee pain thinking about it. What an awful artifact of aircraft design from the 1950s!

Quoting Pihero (Reply 28):
Quoting francoflier (Reply 26):

For hand flying, there's nothing like a big old trim wheel.

doesn't hold a candle to the best ever solution : The Tristar electric trim thumb wheel, seen here :

Absolutely correct Pihero! Easily the best way to trim in history (though Airbus autotrim sure is nice, too!)

Quoting tb727 (Reply 29):
Quoting PGNCS (Reply 27):
There's also nothing like it for finger and knee injuries.

Remember, it will whack you in the knee 3 times before you can say ouch!

  Yes it sure will!
 
tdscanuck
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RE: Boeing Trim:Wheels Vs Lever

Tue Dec 13, 2011 5:52 am

Quoting francoflier (Reply 26):
I still don't like Boeing dropping the trim wheel.

There's nothing like the precision of a trim wheel when hand flying.

The wheel hasn't been directly connected to the stab, at least on a Boeing, since at least the 757 (maybe the 747). On the 777 and 787 it isn't even really connected to the stab, it's just talking to the FBW computers.

Quoting francoflier (Reply 26):
Of course, we're not really supposed to hand fly anything these days, but I've never gotten the hang of using a trim switch which, at least on earlier generation Boeings, provides no feedback and feels like it's connected to the stabilizer through an 18th century yarn spinner...

On the FBW planes it's really nice...perfect trim every time.

Tom.

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