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"Retard-Retard-Retard"  
User currently offlinekimon From , joined Dec 1969, posts, RR:
Posted (4 years 5 months 1 week 4 days 3 hours ago) and read 15452 times:

Retard Command (by Turboprop Mar 16 2001 in Tech Ops)
Why does Airbus have this and not Boeing?
Is the "RETARD" command done automatically or does it need manual input even when autolanding?
Many thanks!

18 replies: All unread, jump to last
 
User currently offlinePGNCS From United States of America, joined Apr 2007, 2821 posts, RR: 45
Reply 1, posted (4 years 5 months 1 week 4 days 2 hours ago) and read 15438 times:

It is automatic and requires no pilot input, at least in the A-320 series.

I guess you would have to ask a Boeing engineer why they don't have it.

I personally don't think it matters much either way from a pilot's perspective.


User currently offlineaar90 From United States of America, joined Jan 2000, 3466 posts, RR: 47
Reply 2, posted (4 years 5 months 1 week 4 days 1 hour ago) and read 15402 times:

Quoting PGNCS (Reply 1):
I guess you would have to ask a Boeing engineer why they don't have it.

Just a guess, but I suspect is is because Boeing planes have the autothrottle system actually move the thrust levers. Since the thrust levers are moving (if the A/T is active), there is no need to aurally announce anything. The pilot is supposed to have one hand on the thrust levers. Secondarily, the Boeings I have flown (737, 757, 767) all have an FMA annunciation of "RETARD" (or similar) for a visual "announcement."

Quoting PGNCS (Reply 1):
I personally don't think it matters much either way from a pilot's perspective.

A professional pilot should be able to adapt to this subtle difference pretty quickly. Probably quicker than getting used to the Airbus' system of not moving the thrust levers with power changes. IMHO, I prefer the quiet/dark cockpit concept (everything normal=no visual/aural annunciations).



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 3, posted (4 years 5 months 1 week 4 days 1 hour ago) and read 15393 times:

Quoting kimon (Thread starter):
Why does Airbus have this and not Boeing?

Airbus's autothrottle works quite a bit differently than Boeing's. On a Boeing, you're either in manual throttle (in which case the command is pointless) or you're in autothrottle and the throttle will go to idle when Flare mode engages.


Tom.


User currently offlinedw747400 From United States of America, joined Aug 2001, 1257 posts, RR: 1
Reply 4, posted (4 years 5 months 1 week 3 days 20 hours ago) and read 15273 times:

Maybe Boeing is trying to avoid confrontations with former Governors...

  



CFI--Certfied Freakin Idiot
User currently offlinemandala499 From Indonesia, joined Aug 2001, 6767 posts, RR: 76
Reply 5, posted (4 years 5 months 1 week 3 days 19 hours ago) and read 15229 times:

Quoting kimon (Thread starter):
Why does Airbus have this and not Boeing?

It's how the Autothrottle is set up between the two manufacturers... Boeing = moving autothrottles... Airbus = non-moving autothrottles... then there's the autodisengagement method.

Quoting tdscanuck (Reply 3):
On a Boeing, you're either in manual throttle (in which case the command is pointless) or you're in autothrottle and the throttle will go to idle when Flare mode engages.

Let me add in plain language... in the Boeing, the autothrottle will move the throttle levers to idle position as well... that gives tactile clues to the pilot (whose hand is supposed to be on the throttle anyways) that the autothrottles are commanding power reduction...

Airbus does it differently... On Autolands, auto-approaches, or manual landings (where many companies still have A/T on as their policy on the Airbus FBW), how do you know when the computer is commanding a power reduction to idle? This is because of the non-moving A/T... The non-moving A/T is partly reasoned with the Airbus A/T being responsive enough to do it's job in maintaining speed during approaches (even in gusty conditions), because the power commanded does not have to be reflected by moving the throttle positions (7 - 8 degrees of thrust lever movement on the Boeings, Embraers and Airbus non-FBW... so it's limited by that on moving A/T). However, that advantage, requires a method to disengage intuitively when flaring to land. Since on a non-moving A/T, the philosophy is so that you don't need to put in a clutch motor on the throttle quadrant, there's no way to disengage the A/T without being counter intuitive. So, the simple solution is... "ask the pilot to disengage it to idle"... On the Airbus FBW, move the thrust levers to idle will disengage the A/T regardless of what it's trying to do, and go to idle...

Both the Boeing retard (A/T moving to idle), and Airbus retard (A voice asking you to (become a) "retard... retard... retard"), are generated by the radio altimeters. So, in effect, it both asks for the same outcome...

Moving and non-moving A/T each has its advantages and disadvantages. But I think that deserves a separate topic.

Quoting aar90 (Reply 2):
Secondarily, the Boeings I have flown (737, 757, 767) all have an FMA annunciation of "RETARD" (or similar) for a visual "announcement."

The Airbus FBW on autolands will show "FLARE" on the FMA in pitch mode, and "IDLE" on the FMA Thrust mode, when in the flare. The A/T will go to idle, but, you need to confirm reduction to idle by moving the levers to idle (which disengages A/T and go to idle). On Boeings, the thrust reduction is there when the levers move towards idle, and, yes, if the reduction is too slow or too fast (which does happen, because of the 7 - 8degs of lever movements through the clutch motor on the pedestal), you hold the power there or chop it faster yourself. Little difference there...

On non-autolands with A/T... the FMA will show "SPEED", and there won't be an automatic power reduction on the Airbus FBW. So, the Radio Altimeter covers that for you in terms of reminder... "Retard Retard Retard" is then heard... and you move the levers to idle...

The "Retard" voice will come at 20ft on all types of A/P A/T combinations, or at 10ft if autothrust is active and one A/P is in LAND mode.

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17000 posts, RR: 67
Reply 6, posted (4 years 5 months 1 week 3 days 18 hours ago) and read 15214 times:

Quoting mandala499 (Reply 5):
(A voice asking you to (become a) "retard... retard... retard

The first two are verbs. Only the last one is a noun.  
Quoting mandala499 (Reply 5):
The A/T will go to idle, but, you need to confirm reduction to idle by moving the levers to idle (which disengages A/T and go to idle).

What happens if you don't "confirm" the reduction?



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinekimon From , joined Dec 1969, posts, RR:
Reply 7, posted (4 years 5 months 1 week 3 days 17 hours ago) and read 15180 times:

Boeing systems seems more logical...

User currently offlineSB From United Kingdom, joined Aug 2006, 216 posts, RR: 0
Reply 8, posted (4 years 5 months 1 week 3 days 17 hours ago) and read 15176 times:

On a non-autoland approach the trust reduction is manual and intuitive just like on the Boeing system - bring the levers to idle and flare - if you don't you'll fly along the runway at 10ft indefinitely. The "retard" call is a reminder, not a command.

For an autoland the autothrust system will automatically reduce the power in the flare, but as the thrust levers aren't backdriven the humanoid has to move them to the idle position and subsequently select reverse thrust. The "retard" call is a command to do so.

I don't have FCTM infront of me but I believe if you don't retard the trust levers on an autoland the aeroplane will keep reminding you until you comply... We don't do autolands so it's not something I consider often - will look it up.

S.



"Confirm leave the hold and maintain 320kts?!"
User currently offlinejetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 9, posted (4 years 5 months 1 week 3 days 16 hours ago) and read 15125 times:

Quoting Starlionblue (Reply 6):
What happens if you don't "confirm" the reduction?

When the ATS is disconnected the engines will run up to climb power. Not something you want to happen during rollout. Not retarding a thrust lever to idle is thought to be a contributory factor in the TAM A320 accident at Sao Paolo in 2007.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17000 posts, RR: 67
Reply 10, posted (4 years 5 months 1 week 3 days 16 hours ago) and read 15120 times:

Thx Jetlagged. What is the logic behind climb power at that point?

Quoting kimon (Reply 7):
Boeing systems seems more logical...

How? They are both internally consistent with the respective philosophy.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinemandala499 From Indonesia, joined Aug 2001, 6767 posts, RR: 76
Reply 11, posted (4 years 5 months 1 week 3 days 15 hours ago) and read 15076 times:

Quoting Starlionblue (Reply 6):
What happens if you don't "confirm" the reduction?

On autoland, it'll keep screaming "retard", which by then, it's not a command/reminder anymore, but it's telling you you're a retard!   
Do you mean "don't confirm" as in don't move the levers to idle? A/T will command approach idle, and stay there... and you won't have ground spoilers until the levers are at idle... which is... asking for a lot of trouble.

This differ on the Boeing because the levers move... you confirm the reduction to idle by the movement made by the A/T clutch motor... but, if the A/T do not go all the way to idle, you still need to bring it to idle yourself, otherwise, you won't get spoiler autodeploy. This is a risk on non-autoland with autothrust down to flare on a Boeing and your hands are not on the throttles.

On both Boeing and Airbus, whether you have the thrust reduction or not, when you flare, you move the levers to idle... simple... A/T or no A/T, that's what you do. Anything other than that, activate TOGA (press the TOGA button on the Boeing A/T and assist pushing the levers forward or leave it alone... and on the Bus, put the levers forward to TOGA).

Remember, no ground spoilers autodeploy on both unless you're on idle stop or have reversers unstowed... (you can manually deploy the groundspoilers using the speedbrake lever on Boeing, but unless at idle, take your hand off the speedbrake lever, and it will stow!)

On the Boeing, if you don't have a reduction, you move it to idle, and wait for disconnection (x seconds after touchdown) or d/c it by pressing the button on the throttle sides. If you reduce the throttles to idle and not d/c the A/T, if no "flare"/"idle" comes up on the FMA... take your hand off the throttle, and it'll power up again.

On the Bus, once you move it to idle, the A/T will disconnect... much simpler.

The main problem of not retarding is actually, the ground spoilers autodeploy... you won't have them if one Thrust Lever is not on Idle (same as Boeing).

Quoting SB (Reply 8):
For an autoland the autothrust system will automatically reduce the power in the flare, but as the thrust levers aren't backdriven the humanoid has to move them to the idle position and subsequently select reverse thrust. The "retard" call is a command to do so.

Yes, on autoland, it's a command... on non-autoland, it's a reminder "hey, don't you think you should retard to idle soon?"   

Quoting SB (Reply 8):
I don't have FCTM infront of me but I believe if you don't retard the trust levers on an autoland the aeroplane will keep reminding you until you comply...

Yes, which by then, it's not a reminder to retard, it's telling you you're a retard    sorry, I just can't resist repeating that one! *me on retard mode*

It doesn't cover it on the FCTM... it covers thrust lock etc... (unless I've missed something)
If the A/T thinks it has failed because a lever is not on idle on touchdown, it'll disconnect and lock the thrust at the lever position (in this case, Climb Thrust) until you move it.

Quoting Starlionblue (Reply 10):
Thx Jetlagged. What is the logic behind climb power at that point?

The thrust lever for A/T on is at Climb Power on manual Thrust... the A/T's limit is at Climb Power (unless you say U're TOGA-ing (non AT function) or MCT (single engine)...
On non-autoland, you leave it there, the autothrottle will try and maintain the speed, with Climb Thrust as it's limit...

Same thing on a Boeing if the thrust lever is not on idle on A/T and you land, until it is satisfied U're on the ground, it will just power up to maintain speed... When it detects "Oh I've landed", it will disconnect the A/T and leave the thrust lever where it is..

The logic behind it is, if you don't retard, there must be something making you NOT retard, to which, one should go-around or maintain speed (and remain airborne) if you're preoccupied... although Go-Around is done by shoving the levers to TOGA and the whole plane switches to Go-Around mode regardless on Airbus, or you press the TOGA button on the Boeing. Now, unless it knows you want to go-around, it will just and maintain the speed until you tell it to do otherwise or it hits the ground... Be you in a Boeing or an Airbus...

Quoting kimon (Reply 7):
Boeing systems seems more logical...

Explaining the Airbus system is not as straight forward... but, operationally, it's much simpler in terms of A/T.

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 12, posted (4 years 5 months 1 week 3 days 14 hours ago) and read 15070 times:

Quoting Starlionblue (Reply 10):
They are both internally consistent with the respective philosophy.


Exactly. Usually you're finished with high thrust when you land but sometimes you might want to go around. What's illogical about moving the levers to Idle to signal that you're finished with the auto-thrust and don't want the engines to spool up again until you start applying a little thrust for taxying?

When an Airbus does something automatically, it's "taking control away from the pilot" but when a Boeing does it, it's "a good thing"... apparently.
Quoting jetlagged (Reply 9):
Not retarding a thrust lever to idle is thought to be a contributory factor in the TAM A320 accident at Sao Paolo in 2007.


More specifically, retarding one but leaving the other at high thrust. I know that's what you meant but it's probably worth clarifying.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17000 posts, RR: 67
Reply 13, posted (4 years 5 months 1 week 3 days 14 hours ago) and read 15054 times:

Quoting mandala499 (Reply 11):
Yes, on autoland, it's a command... on non-autoland, it's a reminder "hey, don't you think you should retard to idle soon?"
Quoting mandala499 (Reply 11):
When it detects "Oh I've landed", it will disconnect the A/T and leave the thrust lever where it is..

Your Airbus sounds like a surfer to me. It would not be out of place, at this point, for the aircraft to start saying things like "Duuuuuuuude, retard...." And after a go-around: "Duuuuuuuuude, that was some gnarly stuff..."   

But I digress.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinekimon From , joined Dec 1969, posts, RR:
Reply 14, posted (4 years 5 months 1 week 3 days 13 hours ago) and read 15022 times:

Quoting mandala499 (Reply 11):
Quoting mandala499 (Reply 11):
Explaining the Airbus system is not as straight forward... but, operationally, it's much simpler in terms of A/T.

A simple anology for a simpletons:is Airbus like mac and Boeing like pc?
In layman's terms:Airbus is a little simpler to fly whilst Boeing need a bit more input?

[Edited 2010-02-19 06:02:01]

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17000 posts, RR: 67
Reply 15, posted (4 years 5 months 1 week 3 days 12 hours ago) and read 14988 times:

Quoting kimon (Reply 14):
A simple anology for a simpletons:is Airbus like mac and Boeing like pc?
In layman's terms:Airbus is a little simpler to fly whilst Boeing need a bit more input?

Not really. The fact that Airbus has more automation in some aspects does not make it a simpler machine. The pilots still need to know all the systems and how to troubleshoot them if something goes wrong. Some things are configured with a different internal logic, but they are not dumbed down for a less savvy user, if you will.

Note that I don't think Macs are dumbed down. Just different.  



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBMI727 From United States of America, joined Feb 2009, 15719 posts, RR: 26
Reply 16, posted (4 years 5 months 1 week 3 days 10 hours ago) and read 14904 times:

Quoting kimon (Reply 14):

A simple anology for a simpletons:is Airbus like mac and Boeing like pc?

Not really. Boeing and Airbus work just as well and buying an Airbus won't cost you more than a Boeing, nor do they look cooler.   



Why do Aerospace Engineering students have to turn things in on time?
User currently offlinejetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 17, posted (4 years 5 months 1 week 3 days 10 hours ago) and read 14888 times:

Quoting Starlionblue (Reply 10):
Thx Jetlagged. What is the logic behind climb power at that point?

Not so much design logic as inevitability. With autothrust disengaged the engine follows the thrust lever command (at the CLB detent in this case).



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineaogdesk From United States of America, joined Jun 2004, 935 posts, RR: 3
Reply 18, posted (4 years 5 months 1 week 3 days 9 hours ago) and read 14820 times:

Fmr Guv Palin was asked if she had the answer to the OP's question, and she of course replied "You betcha!!!"

She went on to say that it was the "right choice" for Boeing to avoid using the term because "its offensive, and we don't do things like those French nutjobs anyway". When told that many US airlines fly the French built Airbus, she glanced at her hand and said "oh, its ok then, cuz the way then French say it, it kinda sounds funny anyway."


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Retard Command posted Fri Mar 16 2001 15:39:38 by Turboprop

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