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TAM A320 crash at Congonhas, Brazil

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TAM A320 crash at Congonhas, Brazil

Old 30th Jul 2007, 08:11
  #681 (permalink)  
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PJ - Pira has answers for you. The (serviceable) 737 system will not allow the Autothrottle to increase either TL position after 2 seconds from touchdown. I am not sure how long the 'Retard' function stays active (I assume 2 seconds?), but even if TL was 'automatically' advanced within those 2 seconds for some reason,
a) There is a direct 'Visual' clue of lever movement, and further
b) Reverser cannot be selected

Regarding A/T function on start-up, yes, if A/T is selected the engine will accelerate to match T/L position. It was, some time ago, 'SOP' in one airline to select A/T before start and I was with a Captain who had inadvertently selected the g/a thrust button during start-up which widened the ground-crew's (and my eyes somewhat). It is, I believe, now back in place in the 'new' Boeing 737 checklists (A/T select, not TOGA).

As far whether both T/Ls need to be at idle to select ANY reverse, I know not, it is not an area I have explored but perhaps we can have someone try (before start up, I suggest, with notice to groundcrew!!). Since a jammed throttle lever would give this problem I am guessing that only the required lever has to be at idle. I have not yet seen an answer to whether the 737 can have one throttle advanced manually with one in reverse or whether they are locked - again not something I have experienced. Perhaps again some kind soul could check before start-up?
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Old 30th Jul 2007, 08:14
  #682 (permalink)  
 
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pira
you could select idle thrust in one engine while the other was above idle in a Boeing Aircraft, but what you would never see is one engine trying to maintain Vapp after touchdown.
Thanks for that... question actually related to selecting Rev on one?
but what you would never see is one engine trying to maintain Vapp after touchdown
Some debate as to whether it's trying to maintain VAPP or just runs up to CLB Pwr. NB the TLs are supposed to be selected to idle prior touchdown... apart from anything else, this disconnects the ATHR, and prevents the aircraft trying to maintain VAPP. Leaving a TL at the CLB detent (well forward) is against all instincts (B+AB!) and will either try to hold VAPP (ATHR engaged) or go to Clb Pwr (ATHR disengaged).

I think it is somewhat unfair to criticise the design architecture, as some are doing, decades after it's introduction. It is is somewhat incredulous to a design / certification procudure that a pilot might leave 1 TL well forward after landing. The issue is the HF one over why pilots are doing this strange habit, and the common factor seems to be a curious reaction to the 1 Rev U/S process. IMHO it is the HF issue that needs to be addressed (Training / SOP change)... much as with the 737 Cabin Alt/TO COnfig system...

NoD
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Old 30th Jul 2007, 09:10
  #683 (permalink)  
 
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Nigel,
I agree with you regarding the HF issue. It is definately the major factor. I do disagree when you say it is against all instincts to leave one thrust lever and retard the other one. It happened in at least 3 other accidents prior to this one and, MAYBE, because the thrust levers don't move in the airbus combined with the fact that the pilot was expecting to use just one reverser and to move just one thrust lever to the reverse detent, he was "mechanically" induced to not retard the other one, although we all know this is not the correct procedure. Just my .2 cents!
Regards,
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Old 30th Jul 2007, 09:25
  #684 (permalink)  
 
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I do disagree when you say it is against all instincts to leave one thrust lever and retard the other one. It happened in at least 3 other accidents prior to this one and, MAYBE, because the thrust levers don't move in the airbus combined with the fact that the pilot was expecting to use just one reverser and to move just one thrust lever to the reverse detent, he was "mechanically" induced to not retard the other one, although we all know this is not the correct procedure. Just my .2 cents!
We're into semantics here It would appear that all (?) of the problems have been with the 1 Rev U/S that generates this, seemingly unpredictable, pattern behaviour.

A lesson for the trick cyclists to look into, and presumably since it is so well defined, simple to address. The shame is that it appears maybe that was in hand, but not in time to maybe prevent this one?
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Old 30th Jul 2007, 09:43
  #685 (permalink)  
 
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pira (& others)
Why would the pilot be "expecting to use just one thrust reverser" when the amended procedure is to use both even where one disabled? One wonders about how well such changes were promlugated in TAM & elsewhere as one or two experienced AB contributors here seemed unaware.
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Old 30th Jul 2007, 09:49
  #686 (permalink)  
 
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MTOW
Why would the pilot be "expecting to use just one thrust reverser" when the amended procedure is to use both even where one disabled? One wonders about how well such changes were promlugated in TAM & elsewhere as one or two experienced AB contributors here seemed unaware.
I think you are over generalising to say the "procedure" was changed. Different operators, national authorities etc. will all have different policies on amending documents, or MEL practices.

My recollection of the 1 Rev U/S MEL in my airline is that it is not recommended to select Rev on the other engine. I have no idea of what our MEL currently states, and am unlikely to until I have cause to read it i.e. I get an aircraft with 1 Rev U/S which might be years away...
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Old 30th Jul 2007, 09:52
  #687 (permalink)  
 
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It can also happen to aeroplanes with A/THR, T/L system similar to B, e.g. A310....

S7 Airlines Flight 778


According to the preliminary results of the investigation[5], the accident was caused by the left engine thrust reverser's failure to deploy. The thrust reverser in question was known to malfunction prior to the accident. When the pilot attempted to slow down the plane by deploying the right engine thrust reverser, the left engine was inadvertently switched into takeoff mode, causing the plane to accelerate. It veered off the runway and hit the concrete barricade at the speed in excess of 100 km/h (62 mph).


http://en.wikipedia.org/wiki/S7_Airlines_Flight_778
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Old 30th Jul 2007, 09:54
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N.O.D.
I was referring to TAM procedure published with their MEL earlier in the thread, which would have been the reference document in this case. Earlier contributors here suggested that changed in the last year.
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Old 30th Jul 2007, 10:38
  #689 (permalink)  
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Max TOW - a caution on your assumption of the date of that MEL to which you refer. Your post #306 which, I believe, was the first link to the TAM MEL is dated 20/7/07. The 'current' MEL linked by that is dated 30/7 which I think was AFTER the AB bulletin? In other words we have no way at the moment of knowing what the MEL was on 17/7. The MEL has presumably been updated since your link.
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Old 30th Jul 2007, 11:17
  #690 (permalink)  
 
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BOAC
Either I'm misunderstanding or you're misreading...when you link as per #306, the TAM page of course shows today's date in the header but their MEL extract (which they put into the public arena as presumably the document current at time of accident) shows 20/7, the date of the press release. The MEL itself is undated, hence my and others' queries about when the procedure was changed from the intuitive "don't use it if it's broken" to "use both anyway".
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Old 30th Jul 2007, 11:37
  #691 (permalink)  
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Yes, Max Tow - quite right, entirely my fault! I missed the date at the top of the 'Nota' and I can not see a date for the MEL pages. Off to dunk my head in a really nasty pit of ............sorry! However, the date is POST 17/7, so can we be relaly sure of the MEL on 17/7?

Of possible interest there appears to be a revision 30 to the AB MEL-
B- For the use of the thrust reversers when landing with one Engine Reverser inhibited refer to :
- For A320 MMEL 02-78-30 Rev 30
. Anyone seen it? May have been issued 23/7.
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Old 30th Jul 2007, 13:04
  #692 (permalink)  
 
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Question.
The same aircraft, with the same crew, and the same TR inop, landed at Porto Alegre only a few hours earlier.
The recording of that landing should still be in the FDR. Have there been any suggestions yet to compare the two landings, and see what procedure was used at Porto Alegre?

The CVR probably won't be of any use for that, because it would have been on a 30-minutes or 2-hours endless loop (depending on type), but the FDR would be on a 25-hours loop or suchlike, so the data should be there.
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Old 30th Jul 2007, 14:13
  #693 (permalink)  
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Pira#691
Another finding was that both CM1 and CM2 were captains. The PF was CM2 (Instructor pilot) and PNF was seated on the left and was a new hire captain.
If true, I assume an ‘Instructor’ Pilot would regularly fly from the RH seat … or would he/she?
.
Rippa mentioned earlier that TAM SOP was for a ‘Capt’ was to fly from the LH seat, I assume an ‘instructor’ would necessarily fly from either seat … comments?
.
.. It will be interesting (from a HF point of view) to find out who was in which seat on the first sector!
.
Side note
.
... a very informative discussion … irrespective of what comes out of the final analysis, the awareness for all crews (B or AB) from this and similar threads is surely worth its weight in gold!
.
.. I bet all crews here (B and AB) have been that little bit more conscious of TL and A/T etc since!
.
P.S Hey Nigel,
My recollection of the 1 Rev U/S MEL in my airline is that it is not recommended to select Rev on the other engine. I have no idea of what our MEL currently states, and am unlikely to until I have cause to read it i.e. I get an aircraft with 1 Rev U/S which might be years away...
.... errrm, what happens if the T/R fails on landing ... are you gunna have time to go digging for the latest MEL revision whilst hurtling down the runway with betty screamin at ya
.
.... of course you were just joking
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Old 30th Jul 2007, 14:23
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For a moment, can we ask the question if it is possible to have an electronic glitch of unknown origin...one that might become more clear in the next few days.

I recall when Fokker said it was impossible to lose all the displays in the F100...but then one day one of our flights lost all displays in flight.

I recall when everyone said there was nothing wrong with the B737 rudder.

Christen J has a good idea of comparing landing techniques with previous landing.

-----------read only if you wish to hear speculation of the highests/lowest order-------------------------

though I do have a horrible feeling that the checkairman said something like: hey, did you know you don't have to pull both throttles back?
the other pilot says: ok, lets try it here.

I pray that this is not the case...but I still remember a DC4 or was it a DC6 in which the jumpseating federal inspector (cab I think) thought it would be funny to engage the control lock while in flight without telling the captain or copilot.

To those who remember, the crew got the control lock to disengage, but the pilot, who wasn't wearing his seat belt, flew up, and hit 3 feather buttons, knocking out 3 of the 4 engines and himself. the copilot regained control, the inspector lost his job.


A fine pilot I knew, who flew the HUMP in WW2 always warned: never touch any switch that doesn't have a lot of wear/tear on it...if it is bright and shiny, don't touch it! (unless its a new plane)
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Old 30th Jul 2007, 14:29
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I pray that this is not the case...but I still remember a DC4 or was it a DC6 in which the jumpseating federal inspector (cab I think) thought it would be funny to engage the control lock while in flight without telling the captain or copilot.
I think this may be the accident you remember:

10/08/1947

American Airlines
DC-4 El Paso, Texas

As a prank, a captain riding in the jump seat engaged the gust lock in flight. The command pilot, not knowing the gust lock had been engaged, rolled the elevator trim tab with no response. When the jump seat captain disengaged the gust lock, the aircraft went into into a steep dive, executed part of an outside roll and become inverted. Neither the command nor jump seat captain had seat belts on and they accidentally feathered No. 1, 2 and 4 engines when they hit the controls with their heads. No one realized it at the time but the feathering reduced power and allowed the co-pilot, who was strapped in, to pull out of the dive 350 feet from the ground.
http://www.planecrashinfo.com/unusual.htm
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Old 30th Jul 2007, 14:42
  #696 (permalink)  
 
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I believe there may be some ergonomic issues. I find the T/L's on the Airbus untraditionally small and with a short "throw" and very little friction damping. I have and have observed a T/L displaced forward when the hand is moved to activate the reverse levers. This is more prevalent with larger type hands and also when transitioning from RHS to LHS or vice versa. It may be displaced by the hand/wrist or shirtsleeve or watch band (hands up how many of you have a large watch?) This displacement is not readily apparent especially at night until the selection of reverse is attempted at which point the asymmetry is discovered and corrected. However with one reverser u/s there is less chance of discovery especially using the "old" MEL procedure. Perhaps the addition of an idle "detent" would be of value.


I agree with flyingnewbie10. All aircraft have one or more unique "booby traps" but I find this one has exceeded the quota.

Last edited by Tree; 30th Jul 2007 at 15:15.
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Old 30th Jul 2007, 15:33
  #697 (permalink)  
 
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@ChritiaanJ

The same aircraft, with the same crew, and the same TR inop, landed at Porto Alegre only a few hours earlier.

As far as I know, yes. But chances are high that PF was'nt the same.......
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Old 30th Jul 2007, 15:52
  #698 (permalink)  
 
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Originally Posted by hetfield
But chances are high that PF was'nt the same.......
Touché. You're right, we don't know.
Still, they were both TAM capatains, both on the same flight, same MEL procedures, same briefing as to inop TR..... may still be worth a look-see.
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Old 30th Jul 2007, 16:17
  #699 (permalink)  
 
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red button

I am no professional pilot. However, thirty years of flying have made me understand that there are moments when your brain is too busy with basic aircraft handling to perform additional flawless and logical analysis, regardless of training and experience. And there are moments when even an IR rated pilot does not look onto the ECAS or listen to some aural warnings. If the end of the runway is rapidly filling your windscreen for instance.
I am a pro in system engineering of computerized systems. As such, I am baffled to recognize that most guys in this thread after some 700 posts are still rather clueless as to what happens when auto this and that is selected and lever this and that is left where it should not be and auto such and such is inop and why it might be possible to have one engine screaming in reverse and the other trying full blast to keep the speed.
A logic that has so many interlocks is a feat to Murphy's law. Not because the logic is wrong, but because it is too sensitive to quirks and because it is far too complicated for troubleshooting when the going gets really rough and time (and runway) runs out.
In the industry we all now the red button for "emergency stop". I wonder if it would not be worthwhile to have such a button in the cockpit that activates whatever means are available to brake and dump lift and immediately stops whatever is trying to accelerate. Of course, it would require some basic interlocks too (like ground mode), but should remain fairly simple. And it would come in handy also on a rejected takeoff.
I know that the pro's do not like the "stop and think later" approach. But maybe it could save the day if the plane goes fast and the thinking slow.
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Old 30th Jul 2007, 17:57
  #700 (permalink)  
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Max Tow

Very good point you brought up, why (speculating) would they not follow the procedure as outlined in the MEL, if I were guessing, I would say that they may have disregarded the procedure, considering the negative aspects (idle thrust slight increase) on the short runway.
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