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Old 1st Feb 2009, 01:38   #1 (permalink)
 
Join Date: Apr 2008
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Throttle Procedure for Boeing Landings

Hello,

I am most familiar with Airbus aircraft procedures, but I have been gaining an interest in Boeing systems lately.

I know that in an Airbus, the Auto Thrust is fully commanded (left in the CL detent) until the "RETARD" callout at 10ft.

However, I am unsure of what the standard (i.e. most common) Boeing procedure is. Is the Autothrottle system used, as in Airbus, or is the throttle manually commanded by the PF?

Also, is the Autothrottle in a Boeing disconnected by moving the throttles manually, or do you have to press the instinctive A/T Disconnect buttons on the sides of the levers?

I'd much appreciate some insight into Boeing throttle philosophies!

Thanking you,
Aaron.
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Old 1st Feb 2009, 09:03   #2 (permalink)
 
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On the 747-400, IDLE is commanded by the autothrottles during autoland at about 25'. When hand-flying, most pilots use manual throttles.

On the 747 Classic the autothrottles must be manually disconnected at touchdown, though they will be driven toward idle in the flare.
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Old 1st Feb 2009, 10:31   #3 (permalink)
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Boeing throttle position is directly related to engine power, whether manual or automatic. You can hear and see the servos controlling the throttle position. Autothrottle is used for automatic landings, though in the event of unserviceability, manual thrust can be used throughout. Autothrottle is never encouraged for manual flying as you can end up with confusing pitch/power couplings as the autothrottle can respond peculiarly and you can end up fighting in pitch. However, some airlines like to use autothrottle in standby on final approach as a safety aid, and it will intervene if speed falls excessively, and will be available for TOGA. Although Boeing don't recommend this, I think is is good practice.
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Old 1st Feb 2009, 11:51   #4 (permalink)
 
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Quote:
However, some airlines like to use autothrottle in standby on final approach as a safety aid, and it will intervene if speed falls excessively, and will be available for TOGA.
What airplane are you talking about? Your statement does not apply to either 747 model.
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Old 1st Feb 2009, 13:24   #5 (permalink)
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737 Classic and NG, 757, and if memory serves correct, 747-400!
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Old 1st Feb 2009, 23:11   #6 (permalink)
 
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The 744 has no "Standby" Autothrottle mode. When Armed, it can be activated via the TOGA, Thrust, or Speed switches, but has no means of automatic intervention if not otherwise activated.
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Old 4th Feb 2009, 20:53   #7 (permalink)
 
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I think what Raiboe is saying is that with the autothrottle engaged and lvl change is used in descet after retard has been anuctionated the fma then displays arm. It allows the throttles to be moved manually to any postion and will not be moved by the autothrottle until the speed is so many knots above the commanded speed. With this in mind with the autothrottle in arm mode it gives you low speed protection should the speed decay into the red band (ng series).
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Old 4th Feb 2009, 22:07   #8 (permalink)
 
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I know of nobody who uses FLCH on final approach.
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Old 4th Feb 2009, 22:15   #9 (permalink)
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I feel soooo neglected.......
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Old 5th Feb 2009, 02:34   #10 (permalink)
 
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Why do I need you when I already have an underpaid FO?
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Old 5th Feb 2009, 06:35   #11 (permalink)
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i am new to this forum and i would to know some few things.
PLEASE COULD HELP ME BY ANSWERING MY QUESTION.
What exact of money you to get an atpl?
What are minimum and maximum age to be hired by an airline as an ab initio?
What are the best academic performance needed to be a pilot?
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Old 5th Feb 2009, 10:45   #12 (permalink)
 
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To follow on from kempus (dude) and Rainboe,

Once on final approach and disconnecting the auto pilot, you do not need to fully disconnect the auto throttle. By “de-selecting speed” i.e pressing the “speed” button on the MCP, “ARM” is displayed on the FMA’s. This means that you have control over the power settings just like you would have if you had pressed the auto throttle disconnect buttons, but in the even of a go around, the auto throttle system will kick in and the thrust leavers will advance automatically to go around thrust once TO/GA is pressed. From memory (it’s been a while since I flew a Boeing) it will give you the flight director “pitch up” indication on the go around also. If you just disconnect the auto throttle fully, you have to advance the thrust leavers yourself in the event of a go around.

Just got to make sure that it’s “speed” and not the “N1” button next to it that’s pressed. That can make life amusing on short finals! (I think that’s why it’s not recommended by Boeing, please correct me if I’m wrong.)
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Old 5th Feb 2009, 11:47   #13 (permalink)
 
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What stue describes may well be valid for SOME kind of Boeing, but not for any version of the 747.

When talking about "Boeing," it is necessary to specify the airplane you intend to reference.
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Old 5th Feb 2009, 13:06   #14 (permalink)
 
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Apologies, indeed, I should have said I was talking about the 737NG.
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Old 6th Feb 2009, 12:51   #15 (permalink)
 
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I wasn't talking about using lvl chng on final approach but in general. Although some landings are like are like if i pressed lvl chng! ha ha!

However straight from the manual look at the last point and the word armed.


Moving the A/T Arm switch to ARM, arms the A/T for engagement in the N1,
MCP SPD or FMC SPD mode. The A/T Arm switch is magnetically held at ARM
and releases to OFF when the A/T becomes disengaged.
A general summary of A/T mode engagement is as follows:
• A/T SPD or N1 modes automatically engage when AFDS command pitch
modes become engaged
• engaging LVL CHG or VNAV climb modes automatically engages the
A/T N1 mode
• engaging LVL CHG or VNAV descent modes automatically engages the
A/T in RETARD and then ARM when thrust is at idle
• if not in a VNAV mode, engagement of ALT ACQ or ALT HOLD
automatically engages the A/T in the MCP SPD mode; otherwise the A/T
remains in FMC SPD
• engagement of G/S capture automatically engages the A/T in the MCP
SPD mode
• alpha floor automatically engages the A/T when armed.

kempus

ps, stue was in the camel bar, how you make it up all those steps without help!
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Old 10th Feb 2010, 13:56   #16 (permalink)
 
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Question Throttle procedures for Boeing and others

Hello,

This is an old topic but what was said make me curious.
If I try to summarize.

1. Hand-flying: fly with manual throttle.

2. Precision approaches:
Automatic landing are done with A/T engaged.
In case of A/T unserviceability, autoland can be realized with manual throttle control.

3. On 737 Classic and NG and 757:
approach and landing can be realized A/T armed (for engagement in MCP SPD I suppose) and manual control of throttle.

=>this is realized with AP disconnect so only in non-precision approaches or in CAT 1, isn't it ?

Do I have well understood?

This makes me wondering on other points.
4. Generally speaking, is the RETARD mode related to autoland ?
I mean, even if you do an approach CAT2 with A/T engaged but without autoland available (failure on AP system design), do pilots have to disengaged A/T to do the RETARD or is the A/T design to RETARD anyway ?
(I realize that a general answer to my question may be difficult due to link to the design of aircraft series. Is it possible to compare Boeing A/T philosophy and Airbus A/T philosophy for the RETARD ?)

5. Then, what about the call-out “RETARD” ? With Boeing A/T, retard is automatically done. So is there only a call-out done by PNF when hand-flying or an auto call-out in both manual and auto-fly ?

Last edited by airfriend; 12th Feb 2010 at 08:24.
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Old 14th Feb 2010, 21:17   #17 (permalink)
 
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Intruder

Can't speak for Boeing, but in my Canadian bizjet, while trying to put in a LNAV/VNAV visual approach (hand flown with AT), I accidently got into FLCH--NO good outcomes there. I caught it.

GF
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Old 15th Feb 2010, 05:18   #18 (permalink)
 
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Going back to what stue said.

In my company it's SOP to Disarm speed and not disengage autothrotle when you hand fly the a/c (737 by the way). This allows the autothrottle be available for a go around and it will kick in when you go 5 knots slow. Not pretty but effective. Just remember to keep asking your PNF to keep disarming speed.

It's also quite easy to hit the speed button as it's the only light on the left hand side of the MCP.

Last edited by cortilla; 15th Feb 2010 at 18:27.
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