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Pilot Commands TOGA; A320 lands anyway

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Pilot Commands TOGA; A320 lands anyway

Old 1st Jun 2001, 23:44
  #41 (permalink)  
northern boy
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Tarmach,

You state that you have "zero hours on the airbus". Just about anyone who has likes it and the sidestick is a total non issue, as you would appreciate if you had flown it. If you want to know what the aircraft is doing try looking at the instruments or even outside!.I've never flown the 777 so I shall refrain from comment on what I am sure is a nice aircraft.
Please lets not have another Boeing/Airbus slanging match.If they wern't safe they never would have been certified.

 
Old 2nd Jun 2001, 00:41
  #42 (permalink)  
Ignition Override
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Northern Boy-I'm not referring to any Airbus here, but let's not forget how many planes with questionable characteristics were "certified" by the US FAA (and allowed to operate with no changes until tragedies took place, while intentionally disregarding serious concerns from overseas operators , i.e. the ATR-42 in icing conditions).

This was in order to "promote aviation", which was the FAA's basic mandate, until the Valuejet (now Airtran) crash.

Have people forgotten the FAA's overriding philosophy in making safety decisions? It is still the "cost vs benefit" analysis. This is understandable, at least to some extent.

[This message has been edited by Ignition Override (edited 01 June 2001).]
 
Old 2nd Jun 2001, 02:39
  #43 (permalink)  
Tarmach
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Northern boy, ok you make some interesting comments. I too don't want to venture into an Airbus/Boeing type of debate. However, I do believe I have a point with the sidestick which is just another facet of the Airbus philosophy. Ok a pilot's job is to process information which appears in visual, audio and say 'feel' or 'seat of the pants' channels. What I'm saying is Airbus seems to present everything to a pilot through his much acclaimed visual channel which could become overloaded in times of high workload. Therefore the main crux of the argument is that a pilot could without the need to visually process the information tell you or I exactly what the aeroplane is doing by simply placing his hand on the control column and not overloading his visual channel which can be used for other things. However with Airbus this does not apply. Ignition Override is correct with the safety issues, many decisions are political.
 
Old 2nd Jun 2001, 02:58
  #44 (permalink)  
Frederic
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Talking

Electricjetjock, you are hitting the nail on the head!
The aircraft in this incident needed the maximum manoeverability and so the maximum amount of G it could get.
In ANY flight condition the maximum amount of G is obtained through applying Alpha max.
The AI FBW is designed to give you alphamax or the G limit when full aft stick is applied. In thid case the aircraft was below it's corner velocity and so the G limit could not be reached, so the FBW gave A-max.
In this case there simply wasn't enough lift available to make the aircraft touch any softer.
So if you would be flying a conventional aircraft in this incident, the pilot would indeed have more authority. More authority to get the aircraft into a higher alpha situation leading to an even higher sinkrate and a misleading higher nose position. It is important to understand that when you are at max alpha, that's it, you got all the lift you can get. Pulling the nose up further will only make the sitiuation worse (you are over the top of the alpha/CL curve).
Although I love AI aircraft I always try to keep an open and logical mind about a sitiuation like this. I don't always defend airbus, but this time, a big thumbs up for AI. People who think the airbus doesn't let the pilot fly the aircraft anymore have a very narrowminded view and a low understanding of FBW systems. What about ALL of the current generation fighters? They limit the alpha and G, and, yes, in a way the pilot "authority", but for a darn good reason. Don't forget that every aircraft has its aerodynamic limits. If this would have been a B757 (don't get me wrong, it's a great aircraft!) it wouldn't have stood a better chance, probably a worst. If you think Boeing is better in that respect, lets start a string about the Brittania Gerona and Transavia Amsterdam incidents! This is not a Boeing vs. Airbus issue... This is a winshear and airmanship issue.
 
Old 2nd Jun 2001, 03:50
  #45 (permalink)  
whats_it_doing_now?
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I'm not getting involved in any slanging match here, but if your last thoughts as the aircraft ploughed into the runway were 'I know I'm doing the right thing, but that smart peace of silicon wont let me!' Wouldn't you be a bit annoyed? I don't fly airbus, but it seems the laws it flies by have cought one or two people out over the years. Could it be that they aren't quite as natural as the traditional ones virtually every other aircraft uses? I know technology has to move along, and many of the systems on the airbus may be a step in the right direction, but it doesn't seem a good idea that the aircraft can override the pilots commands at such a critical phase of flight. It may take a second for the pilot to realise nothing is going to happen, and as in this case, that second may be too much.
 
Old 2nd Jun 2001, 09:51
  #46 (permalink)  
Diesel8
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Frederic,
Great response.

As usual this in turning into the usual Airbus slagfest, particularily when it comes to the FBW system. I simply do not have the time nor inclination to explain all the intricacies and protections in this system to non Airbus pilots. Besides, I am a lousy instructor, not to mention my extremely poor typing skills.

Everytime a FBW Airbus has an incident, everyone rushes to judgement about the viability and useability of the FBW, "it must have been the silly computers", so on, so forth. I need not remind you, as some one earlier did, Mother Nature is very powerful and sometime she wins. Just perhaps the outcome would have been exactly the same in the much flaunted Boeing 777. I do not fly one, so I can only speculate.

I have spent a fair amount of time on the FBW Airbus and absolutely love it. I have yet to see any real problems and find the aircraft a delightful place to work. From experience it seems that those who fly it or have flown it, really like it and most of its detractors have never set foot in one.

D8
 
Old 2nd Jun 2001, 10:45
  #47 (permalink)  
aviator
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Frederic,

It seems to me, that if the Airbus engineering did in fact save the day, why is Airbus revising the software??????

Please help me understand.......

"Revised software, to be implemented soon, will increase pilots' authority over automated systems."

"In the wake of a serious landing incident, Airbus plans to revise the A319/A320 twinjets' automated angle-of-attack (AOA) protection."


 
Old 2nd Jun 2001, 14:21
  #48 (permalink)  
Frederic
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Cool

Dear Aviator,
There is currently not enough information available to me to answer that question. I have not read the accident report and I am not and do not claim to be an aircraft design or test engineer or testpilot. So I simply don't know. HOWEVER, it would seem very unlikely to me that AI would increase the alpha available much above alpha max since that won't increase the lift available. What they might tweak a little is the reaction TIME. Someone made a very good point about the elevator being a bit slow in responce. It is however not possible to make a FBW system with zero responce time since the processors although extremely quick still need some time to "think". There also needs to be some lag and/or limit overshoot built into the system since if you make a totally "stiff envelope protection system this could result in violent oscillations since the system will not allow any overshoots and will thus move the controlls into the "below limit" position to quick. I think it is a good thing that AI are prepared to change and devellop their FBW system. Compare it to your flying skills. The worse pilots there are are those who think they have nothing to learn because they've passed a certain number of hours. Skills are something you devellop during your whole lifetime. There is nothing like a "born pilot". In much the same way, systems need to be develloped.
Open your mind...

PS: Whats it doing now, have you at all read my responce?? Even if the pilots would have totally overridden the computers, they could have only made the situation worse. Alpha max is an AERODYNAMIC limit that provides you with the maximum lift coefficient available. Pulling the stick further aft increases the angle of attack and decreases the Cl wich would result in the sink rate increasing!

[This message has been edited by Frederic (edited 02 June 2001).]
 
Old 2nd Jun 2001, 15:22
  #49 (permalink)  
ex-expat
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Excuse me gentelmen,
But didn't the airplane in question land not only in a high sink rate but also on the nose gear? Wasn't that perhaps the major reason we went from a just hard landing to a very damaged airplane? My Boeing would have at least hit on the mains as I have control of the attitude, not just a vote in it.

Without a doubt the Airbuse has a better cockpit to eat and converse in, but the software in the glass, and the FBW design philosophy is something a pilot must learn to adjust to, trick and fly around.
 
Old 2nd Jun 2001, 19:32
  #50 (permalink)  
Flight Safety
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Gentleman, a quote from the article:

<font face="Verdana, Arial, Helvetica" size="2">The recently completed investigation has shown that the combination of up and down wind gusts and the flight crew's actions on flight controls led the aircraft to hit the automated systems' high angle of attack protection and prevented a normal flare.</font>
The pilot couldn't even flare the airplane prior to touchdown. The "Alpha Max" function was activated prematurely because the AOA was calculated improperly in the unique sequence of events. This is why the software mod is required.

One of the main purposes of the flare is to arrest the vertical descent speed just prior to touchdown is it not? Or am I the only one who sees anything wrong with this?


------------------
Safe flying to you...

[This message has been edited by Flight Safety (edited 02 June 2001).]
 
Old 2nd Jun 2001, 19:36
  #51 (permalink)  
Joey Gray
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Hi Fella's

I fully agree with Thrust " Any plane will do the same regardless of protections- If Mother Nature's not on your side that day you're in for a rough time" As far as Tempo-TSRA are concerned, you guys need to understand the plane a little better, If you nudge the thrust levers anytime out of the Clb Gate you will get more thrust- you can apply this whenever yourspeeds bleeding on short finals so try it next time dont forget to get the levers back to the climb gate quickly or else you will hit TOGA and the Capt will be p*##@^ off.
 
Old 3rd Jun 2001, 01:29
  #52 (permalink)  
Critical Mach#
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From a very much edited report coming from the operator of the 320 damaged in BIO.

The A320 softaware prevented the crew from obtaining Max AOA when GA was called.
During the approach and below 150feet a very potent downdraft hit the aircraft. The F/O was PF at the time and pulled back on stick to arrest the rate of descent. At the same time the capt called for GA while pulling on sidestick without pressing priority button. The computers sensed that the sumation of both inputs would have placed de Aircraft beyond MAX AOA (Flaps 3) and responded with a zero increase of AOA. AOA at the time was 3degrees. Aircraft impacted on rwy at 3 degrees AOA main gear first with 4.8g´s and bounced. During the second impact nose gear collapsed.

´Regards



[This message has been edited by Critical Mach# (edited 02 June 2001).]
 
Old 3rd Jun 2001, 09:14
  #53 (permalink)  
Flight Safety
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Gee, it's worse than I thought.

I thought the AOA was being misculated because of the conflicting wind inputs and pilot responses, but now I see the computer made a more fundamental logic error. If sumation of the pilot inputs would have pitched the airplane above AOA Max, then why not just sum the inputs to the value of Alpha Max? I suppose that it might not have occurred to the software engineers that in an emergency, both pilots might pull back on their respective joysticks at the same time. Pitching up to Alpha Max is still safe, while not pitching up at all could be deadly.

Gee whiz...
 
Old 3rd Jun 2001, 09:26
  #54 (permalink)  
411A
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AirBus technology seems not to work very well in critical situations. The B777 FBW system does seem to keep the pilots in the loop to a much greater degree.
Have noticed that the A330/340 have not had as many problems. Would this be because these types fly longer sectors and make fewer approaches/landings?
 
Old 3rd Jun 2001, 11:08
  #55 (permalink)  
TvB
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Cool

From my webpage at www.aviationsafetyonline.com
with kind regards
TvB

ACCIDENT OF AN IBERIA AIRBUS A 320 IN BILBAO
Airbus Industrie initiates a move to increase pilots authority over automated system

by Tim van Beveren, Miami


The landing accident of an Iberia Airbus A 320 on March 7 in Bilbao, Spain, shows vital consequences for Airbus Industrie. The European aircraft manufacturer recently surprised the aviation community by announcing that it is going to revise the software programming of its automated Angle-of-Attack (AoA) protection, also known as “alpha-protection”. This highly sophisticated safe-guard system has been installed on all of Airbus’ fly-by-wire aircraft, dating back to the first delivery of an A320 in 1988. The alpha protection has always been regarded as one of the prestigious, outstanding and truly safety-enhancing features of the modern Airbus products. The computer guided system prevents the aircraft of entering a stall, resulting from a too high angle of attack. If, for example, the pilot would inadvertently command too much nose up attitude in a climb, which would lead to a subsequent loss of lift, the system will automatically lower the nose by acting on the elevators and thereby prevent the aircraft from entering into a stall. The Airbus A 320 Flight Crew Operation Manual (FCOM) defines it as a system “which provides protection against stall and windshear, (and) has priority over all other protections.” (Emphasis added)

However, according to first released findings of the Bilbao accident investigation, the ‘activity’ of this safety feature was a contributing factor in the event: the alpha-protection contradicted the desired pilots action. During the final approach to runway 30, the Ground Proximity Warning System “sink rate” warning was triggered and the crew applied TOGA-power (Take-Off/Go-Around power) to abort the landing.

Yet, special attention should be given to the specifics of the scenario: At around 23:10 local time Iberia flight 1456 was approaching Bilbao’s Sondica airport. The flight originated in Barcelona. On board were 136 passengers and a crew of seven. As the flight was a training flight for the First Officer, there were three pilots in the cockpit. At the time of their ILS approach the crew encountered a thunderstorm and was advised of light turbulence and surface wind speeds from 240 degrees of only 8 to 9kts, but no windshear. The airport is dreaded among pilots for critical conditions, - especially in the winter, and is not equipped with improved weather measuring equipment or modern windshear detectors. The airport was the scene of two other weather related accidents that occurred during the preceding 15 days and other three in the previous five month.

Bilbao’s Air Traffic Control did not mention to the Iberia crew that, just shortly before the A320 approach three other aircraft had tried unsuccessfully to land at Sondica and had finally decided to divert. According to statements of airport personnel to local media after the event other flights also diverted directly to their alternate, without even trying to land in Bilbao.

During the final approach the A320 encountered heavy turbulence at about 200 ft AGL, with gusts up to 65mph, an 1.25g- updraft, followed by a downdraft and tailwind gusts at an altitude of 70-50ft. The associated change of wind direction during the event clearly points to a windshear encounter.

According to information released by Airbus’s deputy director of flight operations support, Cpt. Michel Brandt, the flight crew applied a forward sidestick input during the updraft, then an aft input to reduce the increasing sink rate. When the GPWS alerted the crew about their unusual increased sink rate, the pilots decided to perform a go-around and applied TOGA-power. But the crew’s desired and commanded action was not performed by the aircraft. As the alpha-protection was triggered during this event, the system commanded a nose down signal, which was performed, even though both pilots had their sticks full backward, commanding a “climb”. Nevertheless the airplane touched down with all three gears struts almost simultaneously and with an estimated vertical speed of 1,400ft./min. The nose gear subsequently collapsed and the plane slid along the runway for about 3,280 ft. before coming to a stop. During the emergency evacuation, four passengers and some of the crew received minor injuries, among those, one passenger, a 75 year old female, was hospitalized.

The barely six month old aircraft received substantial damage, including the wing structure and the engine nacelles. It is beyond economical repair and therefore should be regarded as a total loss. The accident has been under investigation by the Spanish CIAI (Comisión de Investigación de Accidentes e Incidentes). For Spain’s national carrier Iberia this accident represents the first loss of an Airbus A 320. The company operates 85 modern Airbus fly-by-wire aircraft (A319, 320, 321 and 340) and last year transported over 30 million passengers.. The Spanish company CASA is part of the European Airbus consortium.

Back in early April, the French Civil Aviation Authorities (DGAC) had issued an airworthiness directive (AD) for the A319/320 aircraft. It ordered the crews to fly at least 10 kts. faster and use only “CONFIG 3” (flaps 3) setting on approach in conditions with gusts greater than 10kts reported wind increment (max. wind minus average wind), or when moderate or severe turbulence on short finals has to be expected. In such events, the crew must select no more than flaps 3 and maintain a minimum approach speed of Vls (= “lowest selectable speed&#8221 + 10kts. If the GPWS “sink rate” warning occurs below 200ft, an immediate go-around is required. Operators incorporated this AD-note into special bulletins for their pilots, but no additional information about the nature of this special procedure was given so far.

In the light of the accident occurring only four months ago, and the sometimes lengthy ‘normal’ timeframe for implementation of safety revisions after an accident, it appears to be of “amazing speed” how Airbus Industrie, - even in the absence of a final report, has already decided and performed a modification on the alpha-protection control laws. This was done in an approach “to increase the flight crew’s authority”, - as Cpt. Brandt was quoted by media. - A step applauded even by staunch Airbus critics among the international pilot community. A revised software version is expected to be validated this month and has already received certification by the French Civil Aviation Authority (DGAC) and the European Joint Aviation Authority (JAA). Airbus plans to implement a “rapid retrofit program” for its entire A319/320 fleet.

 
Old 3rd Jun 2001, 18:11
  #56 (permalink)  
Frederic
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Red face

Seems like the A320 didn't reach alpha max at all. If both pilots commanded a-max this might have led to the FCC's overanticipating the alpha demanded. If this would have been the case the problem would not have been a limit protection problem, but an input problem. On one hand it's a shame this happened, but on the other hand I think this incident means a great step forward in FBW devellopement. IF...
Looking forward to reading the report. It would still surprise me if AI would allow the FBW to exceed a-max. To allow it to make a transient overshoot would make sense to me, but just to increase its value wouldn't. But this incident smells of an input problem. So in anticipation of more detailed info I will now shut up and let the AI-bashers vent their anger. (beware though, I will bite back) Would still fly the A320 anyday...
PS: Flightsafety: Normally if both pilots apply full aft stick the FCC command maximum G (2.5) or max alpha, wichever comes first. So it must have been an input or reaction time problem . Another thing I don't understand is that since below 100 feet the aircraft passed from normal to direct law, the envelope protections should have been removed by that time. Strange...

[This message has been edited by Frederic (edited 03 June 2001).]
 
Old 3rd Jun 2001, 19:29
  #57 (permalink)  
Flap 5
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There are a number of replies here which start with 'I don't want to get into a slanging match but ..' and 'I have never flown Airbus but I don't think its much good'. So what follows in these posts is hardly worth reading. I have got over 3500 hours on the Airbus FBW aircraft and over 2400 hours on the B737. The Airbus has its faults, which are often brought out when an unusual incident happens, but they are all excellent aircraft.

It would appear in this instance that the requested input from both pilots was so extreme that the system would not allow it and retained the existing AOA. I would think that Airbus will now change the software to allow this to be accepted by the computer. After all a request of full back sidestick on both sidesticks should be responded to more rapidly than normal by the system, not thrown out as unacceptable. It's not perfect, but it is still very good.
 
Old 3rd Jun 2001, 19:59
  #58 (permalink)  
TowerDog
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Heavens Gate:

You mentioned the Delta L-1011 windshear accident in Dallas as "TOGA power and proper attitude" did not prevent the accident.

Wrong. It was indeed preventable if proper attitude had been flown.

As this happened in 1985. most airlines did not have the Windshear Escape Maneuver simulator profiles we have today.

The Delta crew did a "normal" go around and never pitched up enough to prevent the sink rate encountered.

Nowadays we are taught in the simulators to pitch up enough to actiavate the stall warning, then stay there.

Never flown an Airbus of any kind, how is the
windshear/microburst escape maneuvers taught in the sims?
Full aft input of both side sticks cancel out
the message to the computer???
Must be a typo or misunderstanding, nobody can get that certified...?

------------------
Men, this is no drill...
 
Old 3rd Jun 2001, 20:01
  #59 (permalink)  
Anti-ice
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Red face

I've read pieces of this thread , and again a question mark seems to hang ominously over the capabilities / authority of the airbus FBW systems.

I'm not either pro/anti airbus,but do feel more than a shade of concern over the integrity of it's onboard equipment.

The close call on the LH A320 sounds just a little too close to be comfortable - well done guys - , but to have your overall command of an aircraft over-ridden by a computer in such a critical phase of flight seems almost unthinkable.

The series 'black box' is being shown on Sky Wings again at the moment ,with last Fridays programme focusing on Human error -v- Automation.

A clip I've never seen before featured a (Tarom?) A320 seemingly out of control over CDG - the aircraft rocked and yawed over the video cam filming it with engines howling, nose high & gear down at an altitude of i guess 2-3,000 feet .I couldn't believe what i was seeing at first, I dread to think of the reactions onboard.

Inevitably there will be the usual boeing versus reactions to this , and doubtless there are hundreds of airbuses around the world doing a 1st class job, but are airbus open to reviewing and changing systems to ensure the highest level of confidence in them?
 
Old 4th Jun 2001, 00:36
  #60 (permalink)  
max_cont
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I wouldn't normaly post on this subject because I don't fly Airbus, only Boeing.

I will admit to disliking the idea that I cannot override a computer, especially when it's my ass that's strapped to the seat and not the system designers.

The A/C was designed by people. People are not infallible, they can't think of everything.

The FBW is a great idea, IF you give the pilots a last "out", in that "not considered" scenario.

As someone has already stated, "mother nature" will sometimes come up with the unexpected. Any system as hugely important as the flight control system had better have an answer, even if it's just giving back full control to the pilots.

I know I will probably be slated for this post. Some Airbus pilots seem to respond in an almost rabid manner, to any criticism aimed at the A/C. (we only operate them guys)

I have only been flying Boeing airplanes for 13 years. I accept that there are faults with the design, some found and no doubt some still to be discovered.

Why is it that some pilots will not even consider, that Airbus could possibly have got some of it wrong?

I write this knowing that in a couple of years I will be OPERATING the A330, since Boeing haven't designed a new airplane to compete with AI.

 

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