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TAM A320 crash at Congonhas, Brazil

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TAM A320 crash at Congonhas, Brazil

Old 27th Jul 2007, 01:08
  #561 (permalink)  
 
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Does anyone know WHEN/WHY the MEL procedure changed from "preferable not to select REV on the affected engine" to "select REV MAX on both engines (including affected side)?
Also mentioned already, the Fadec will command increased idle thrust on affected side -- is this to be ignored by pilot?

downsouth has mentioned preference to leaving engine with inop reverse on idle...
The current MEL calls for selecting idle on both reversers and then both to Max reverse. I can't give you a specific date on when the revision was issued by Airbus but I imagine it was in early 2006. I understand that Airbus, recognizing that not everybody want's to use Full reverse all of the time, will be changing the second step from "max" to "as req'd" (not the actual words they'll use) sometime later this year.

I guess the "as req'd" will take care of your second question to some extent.
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Old 27th Jul 2007, 01:27
  #562 (permalink)  
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flyingnewbie10;

1 - If the A320 touches down with the autothrust engaged (I suppose it is the most usual), is it mandatory to put or keep BOTH levers exactly in IDLE detent or BOTH levers in reverse (if reverse thrust is deployed) in order to desengage the autothrust ?
First, it is not "usual" to touchdown with autothrust engaged. The thrust levers are both to be pulled back to "IDLE" (zero degrees thrust lever angle) by 20ft on a manual landing and by 10ft on an autoland.

The AOM does not specifically state that "both" thrust levers are to be pulled back to IDLE because there is no conceivable reason on Airbus or any aircraft I have ever flown not to close the throttles completely when landing.

I hastily add that this is not a comment on potential and actual errors made by crews - that is a human-factors issue however, and not an operational issue. That said, the AOM does specify the plural, "Thrust Levers" in all documentation in all normal and abnormal Airbus AOM SOPs I have read.

2 - If the plane touches down with autothrust engaged and soon after BOTH levers are put in reverse, what happens to the engine with the faulty reverse ? Will any alarm sound ? Will the AutoThrust keep engaged in order to reduce thrust in this engine with a faulty reverse ?
As per documentation in our AOM, the engine with the locked out reverse will increase it's idle RPM slightly and thereby increase forward thrust slightly.

No, no alarm will sound. There is no need. Operating with a reverser locked out is in the realm of "normal" operations with some operational considerations written and , while not written, experienced airmanship brought to bear. A u/s thrust reverser is not an abnormality in the same sense that jammed slats/flaps etc are. A u/s reverser in and of itself is no reason to stop operations or divert. That said, there are a host of reasons which may (and should) influence that initial position.

The autothrust will not keep engaged. It is disengaged (and cannot be re-engaged through thrust lever position alone) when the thrust levers are pulled back to IDLE. In fact, they disengage slightly above 0-degrees TLA but that is technically academic point at this stage.


3 - If, however, the plane touches down with autothrust engaged and soon after ONLY ONE of the levers is put in reverse and the other is kept at, let's say, only 2 degrees over idle position (without the "donut" pointing neither idle nor Max Climb position), will the AutoThrust simply desengage or put the left engine at Max Climb power ? And as I understood about the A320 Thrust system, would the lever even so keep steady at those 2 degress above the idle "donut", making it difficult to the pilot to realize that the engine was at full forward thrust ?
To be a bit fussy, I'm not sure of the exact TLA at which the autothrust disengages but I believe it to be slightly above zero degrees TLA.

However, I know what you are driving at and my response to the question is, the TLA position "restricts" the amount of available thrust level to the thrust lever position. I cannot imagine a design which, in some fashion, would "see" a partially-open thrust lever, and, without crew input, "decide" to increase to TOGA thrust on its own without the thrust lever so moving to permit this - such a serious design flaw would and should be immediately seen by engineers long before the airplane made it into production.

If for whatever reason, (human factors, rapidly unfolding/deteriorating circumstances, environmental factors such as turbulence, darkness, unfamiliar operating circumstances, surprise, etc), a thrust lever remained in a position which would permit the engine to increase power, it will do so. There is a note in the AOM in the Start section that warns the crews to ensure that the thrust levers are at the IDLE position before start because they will accelerate to the rpm/thrust setting permitted by the position of the thrust levers. The item is in the Before Start checklist, but still the incident has happened more than once.

As an aside, I have many thousands of hours on A319, A320, A330 and A340 aircraft having flown them since 1992 and not only think the aircraft is superbly designed and exceptionally well-thought out but having had my share of abnormalities and "interesting situations" in Airbus aircraft over the years as well as abnormal situations which, had they been slightly different, had the potential to overwhelm a crew with information-overload, I have never seen the capriciousness which at times is so heavily attributed to the design in some of the posts here and, it seems interminably, elsewhere. It is a tiresome dialogue with little potential for settling to the agreement of all, the point of the comments being, it appears, just a good public joust instead. (I have also thousands of hours on Boeing 727/767 as well as Douglas DC8, DC9 and L1011's and they compare favourably but not better or worse, just different - each with its idiosyncracies which must be learned and accomodated by professional crews).

Cheers
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Old 27th Jul 2007, 01:33
  #563 (permalink)  
 
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My friend flies the A320 and when I asked him about landing with one TR locked out he said training never really covers that sort of thing so he didn't know. He said a lot of pilots don't understand some of the automation of the Airbus so even check pilots don't always get it right. Hopefully the DFDR and CVR will tell if changes need to be made. I only flew Boeings so always got what I asked for and nothing else
This is quite disturbing, but I won't give it credence unless I hear it directly from pilots who flie the aircraft
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Old 27th Jul 2007, 02:39
  #564 (permalink)  
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crashed into a building owned by TAM Airlines itself at 108 MPH. All through the runway there were rubber marks left by the landing gears...
108mph? Upon what is this based? The FDR has not been released so discussions of speed are academic and speculative until that occurs.

Rubber marks "left by the landing gears" on a runway which would have been well used even as it was freshly coated, do not mean a thing. We do not know about anti-skid performance nor does "rubber marks" tell us a thing. Someone mentioned anti-skid "chatter" (deeper/shallower marks) in the grass where the main gear left it's marks. Nonsense. You must accept my discussion as one, not the only, explanation of the autothrust system. No conclusions are implied or drawn. We must wait for the FDR.
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Old 27th Jul 2007, 03:48
  #565 (permalink)  
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However the information about the speed of the A320 was confirmed by local authorities. And the Infraero (the company responsible for airport administration in Brazil) footage does not let too much doubt about it.
Forgive me - wiith no disrespect meant whatsoever, "local authorities" means nothing in terms of a formal accident investigation even though such testimony will be taken as part of any such investigation. Unless it's from the FDR, (where available, of course - and this one is), such "information" has the same status as hearsay.

Re, "not too much doubt",

Perhaps for those who wish to draw unsubstantiated conclusions, but that is not the evidence upon which flight safety investigations are built - far too much can be manipulated in a video which does not have validated "chain of evidence possession" constraints in terms of handling. The DFDR is the only source for such information. You have acknowledged that. Why are you pursuing avenues outside of your acknowledgement?

By the way:

Do you confirm that even if the AutoThrust kept engaged at touchdown for some reason, the TLA position would be respected by the FADEC in case the right TL was just "a bit" over the idle donut ? The right engine would not "accelerate" more than those two or three degrees shown by the TLA ?
Look - you say you've read the thread. My post provides sufficient information on the Airbus autothrust system for any professional pilot to comprehend. Where are you going with this line of questioning?
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Old 27th Jul 2007, 04:12
  #566 (permalink)  
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Found a post flight picture that appears to show one of the tires had no rotation, any guesses?

xx
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Old 27th Jul 2007, 04:50
  #567 (permalink)  
 
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I'l bite
starboard inboard?
chilling shot
y
[ a plane gazer geezer]
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Old 27th Jul 2007, 05:07
  #568 (permalink)  
 
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The choice is between accepting a minor expected degradation or incurring the risk of a surprise serious degradation in decelleration.
Ratherbeflying: Good point. I had never seen it that way... makes a lot of sense to me now... Thanks
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Old 27th Jul 2007, 05:15
  #569 (permalink)  
 
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DreamLand:Couldn't that have happened when it impacted a car on the motorway??

If not, what a day... Wet rwy, 1 rev inop, residual braking / 1 antiskid inop...

Anyway... it's 2 am... I better go to sleep... good night.
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Old 27th Jul 2007, 07:18
  #570 (permalink)  
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Dream Land
.
The rim circ is intact ... it would not be if the wheel had locked after tyre failure at forward speed.
.
The tyre damage is likely post impact fire
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Old 27th Jul 2007, 07:29
  #571 (permalink)  
 
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108mph? Upon what is this based? The FDR has not been released so discussions of speed are academic and speculative until that occurs.

PJ2,

The speed data derived from the FDR was officially released a few days ago - the Brazilian authorities confirmed an NTSB finding that the aircraft was travelling at 175km/h. Which in old money is 94kt or 108mph, as stated.
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Old 27th Jul 2007, 07:49
  #572 (permalink)  
 
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Question Alfa floor on A320

Not an expert on this type aircraft but got from A320 FCOM and some related documentation that there is an automation feature that prevent the crew from flying this plane at dangerous low speeds. In flight the FMGS will call for automatic TO/GA to preven a stall situation. TO/GA will be called independent of TL position as long the speed drops down to a certain threshold. The TO/GA demand by A.FLOOR protection will lock the TL inputs (any movements on TL will not have impact on engines). The only way to restore TL function is to desingage manualy the A/Throtle on FCU......On current A320 crash I was just wondering what would happend if crew fail to follow the "RETARD" aural warning just prior the touch down and did not put the TL on demanded IDLE position to automatic disconect the A/Throltle. Would the A.Floor kicked in due to a speed drop and acelareate both engine at max power, locking the TLs?...On speed running, short runway, night, bad weather conditions, the crew may not had time to figure out the situation and disconect the A/Thrust on FCU....

Last edited by c9jfb; 27th Jul 2007 at 08:08.
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Old 27th Jul 2007, 08:20
  #573 (permalink)  
 
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PJ2 - a most useful post on the workings of the Airbus throttle system - thanks for that. I fly a Boeing, have never flown an AB, so have no knowledge of how the system works.
I'm still a little unsure however where all this speculation about the reverser is going, I have always been taught that the majority of decelleration after landing comes from the wheel brakes, and the most important thing to get the brakes working, is to get weight on them by using the spoilers.
What triggers the autobrakes and autospoilers in the 320? is it both levers to idle, or something else? i.e if one lever had inadvertently been left just outside the gate would it prevent the brakes and spoiler from operating?
I can't imagine that the pilot would have left one lever forward - on a long runway, attempting a nice soft landing? maybe, but I still can't see it. On a short wet runway where you need to put it down hard right in the zone, then I can't see anyone not retarding both levers fairly aggressively in the flare. However as per my question, if for some reason the left lever went all the way into reverse and the right lever somehow didn't quite go to idle then would this prevent the spoilers?
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Old 27th Jul 2007, 08:28
  #574 (permalink)  
 
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Angel autothrust disconnection

This refers the discussion going on here and a very detailed answer on the issue which should?? have put to rest the doubts. Again to clarify, on 320, as you flare, retard retard starts to sound and you are required to bring BOTH (emphasis mine) TLs to idle. I really dont comprehend why a sane person will not bring all TLs to idle for landing.
In case, you DO NOT or DELAY bringing the TLs to idle, autothrust automatically cuts off. Some of you 320 jocks might have experienced it while trying to delay bringing the TLs to idle to "cushion" landing with some thrust kicking in and then bringing TLs to idle. In this situation autothrust cuts off and the appropriate "autothrust off" caution comes on. However, since you are landing and the TLs come to idle and then to reverse, it goes off soon.
What is the meaning of "autothrust off" - it just means that the FADEC will now set engine thrust corresponding to whatever is the position of TLs. So, in case, with autothrust cut off, if any TL is above the idle position, the FADEC will set thrust on THAT engine to correspond to the position of TL (represented by the donut).
In airbus training, it is clearly emphasised to bring BOTH TLs simultaneously to idle at flare. If this direction is not followed or overlooked, then you are playing with fire.
Like it is said in aprevious thread, you need to know with the idiosyncracies of a particular type and follow them and not invent your own procedures or let previous habits of some other aircraft get in the way.
Just for a B type, I wouldnt be looking at the thrust levers at flare to see where they are. Do you?
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Old 27th Jul 2007, 08:45
  #575 (permalink)  
 
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Alpha Floor

ALPHA FLOOR is inhibited below 100 feet RA on approach.
TP
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Old 27th Jul 2007, 09:43
  #576 (permalink)  
 
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I am not rated on the A320 (yet).

What triggers the autobrakes and autospoilers in the 320? is it both levers to idle, or something else? i.e if one lever had inadvertently been left just outside the gate would it prevent the brakes and spoiler from operating?
The autobrakes get their go signal from the ground spoiler actuation which in turn is triggered via the TL position. Movement of the TLs into the 0 degree (idle) or reverse area signals the logic to deploy the ground spoilers when the aircraft is on the ground - as detected by wheel tachs and LG strut compression switches.

Ground spoilers can also give partial lift dumping when no TL is
greater than 20 degrees and at least one is in reverse, however full deflection of all panels requires both TLs to be in idle position or reverse.

Manual braking is always available with full anti-skid protection no matter the TL position (as far as I know.)
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Old 27th Jul 2007, 10:05
  #577 (permalink)  
 
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so IF the TL's are not in the idle position (i.e one of them left slightly out) then the spoilers will not deploy?
All the braking in the world ain't gonna stop you on a short wet runway with no spoilers.
This is just my opinon, but if one of the TL's is left out of idle then its not the thrust that engine may or may not generate that is the enemy, its the lack of spoilers, which in turn means that aquaplaning is likely and there is little or no weight on the wheels.
I still cannot comprehend that an experience, skilled pilot will not retard the levers when landing, in any aircraft. There must be more to this than meets the eye.
I can see that you could leave one slightly above idle, or push one back out when applying reverse on the other, but even that should give you some spoilers -although maybe not enough to stop on a short rwy.
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Old 27th Jul 2007, 10:09
  #578 (permalink)  
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Understood, but 20 degrees TLA (thrust lever angle) is quite a bit to overlook.
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Old 27th Jul 2007, 10:18
  #579 (permalink)  
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Ground spoiler actuation logic is as follows.

The ground spoilers partially extend 10 degrees when reverse is selected on at least one engine (the other engine at idle) and one squat switch is triggered (one main gear on ground firmly). The ground spoilers extend fully on landing when both main gears have touched down and
either
* Ground spoilers are armed and thrust levers (both) are at or near idle, or
* They are not armed and reverse is selected on at least one engine (other at or near idle)

"Idle" here means TLA less than 4 degrees, or less than 15 degrees when below 10 ft RA

The main gear touchdown condition is triggered for both mains when their wheel speed is greater than 72 knots, or when the squat switches are on (struts compressed) and the RA is less than 6 ft.

Thrust reverse actuation requires one FADEC channel signalling throttle reverse *and* both main gear struts compressed *and* TLA reverse signals from at least one SEC.

This logic is changed slightly from when I wrote my paper in on the braking logic in 1994.

PBL
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Old 27th Jul 2007, 11:02
  #580 (permalink)  
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PJ2 and others - thank you for the most informative posts so far on the 320 systems. I have learnt more in your few posts than in all the 500+ before.

What is becoming sadly clearer to me is that what was being said in the 80's as the first ABs crashed with the crew unaware of operating mode and protection systems in place is still valid. TRAINING. Are we keeping up with automation and systems?

I am starting a new thread on the 'Safety' forum so we do not pollute this one. NB all those 'sensitive' AB souls, this is not an 'Anti-AB' topic. It is training in general so don't be frightened to look and contribute if you feel the need.

Could I also point out that the position of controls and state of bits of the aeroplane after impact with a building at around 94kts and an intense fire will not yield much to the casual observer and should be left to the accident investigation team?
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