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Ignition Override
28th May 2003, 12:51
A friend just told me about an article in this paper about Airbus' alleged awareness of some sort of rudder problems in the A-300 or 310 before the huge AA tragedy on Long Island, after departing JFK. Tonight I went to two gas stations, a grocery and a bookstore: all of today's copies were sold out. My understanding was that it is somewhere in today's paper, and the friend said that the article is quite interesting.

Could anyone possibly put some complete excerpts on Pprune? The intention here is not to criticize the aircraft or the manufacturer, but to find out what was printed in the article. I was impressed with the cockpit layout and have only jumpseated on it.:)

BOAC
28th May 2003, 14:18
With just a TINY bit of EFFORT (http://www.usatoday.com/travel/news/2003/05/27-air-safety.htm) :{

My mouse is now exhausted.

denachtenmai
28th May 2003, 14:51
Remember the D.C 10 saga??
regards, denachtenmai

Schrodingers Cat
28th May 2003, 15:59
Surely this can't have been written by a journo? It's factual, balanced, and accurate, quotes impeccable sources with no speculation......Branson will fly Concorde next!!!:eek:

XL5
28th May 2003, 17:59
Indeed, a most disturbing scenario. Poor IO wildly dashing between convenience store, gas stations and bookshop in a frenzied but futile attempt to read USA Today's definitive words of wisdom on Airbus tails and corporate cover-up. Jolly good job BOAC and his mouse were at hand to save the day; Bravo! Well done the pair of them! One can only hope that the Airbus chickens come home to roost on this one.

PS.....Cannot believe that USA Today sold out because of a keen interest held by the good folk of Memphis in aeronautical matters, it's more than likely the high sales volume is attributable to a report somewhere in the 'purple section' of yet another sighting of Elvis in a Burger King.

Phoenix_X
28th May 2003, 18:12
It's not all that fair to blame Airbus. In both incidents the pilots used full alternating left and right rudder. Now I'm not at all saying I would never do thesame, however, authorities, including the FAA do not require the rudder to be able to withstand the associated forces.

Airbus designed their aircraft to meet those requirements, and they cannot be blamed for doing so. Sure they could make it stronger to make it safer, but hey, the safest option would be to stop producing the aircraft completely. No aircraft, no crash.

I wonder if swinging a B7X7 (where x=0-7) rudder left and right a few times would keep it in one piece.

If the FAA wanted to prevent this from happening, they shouldn't have allowed an aircrafts rudder to have more power than it can withstand. They should not blame an aircraft manufacturer for not telling them the rudder wasn't able to withstand what it's not required to withstand.

Having said that, ofcourse, sharing of information is of the highest importance, and there is no excuse for not fully publishing any report. Don't blame just Airbus though.

stillalbatross
28th May 2003, 18:26
Have to agree. Doesn't paint a wonderful picture of Airbus but when one looks at how Boeing have behaved after the repeated 737 uncommanded yaw crashes, or the 747 igniting centre tank or inflight breakup, or ........ Hopefully something good will come out of it all.

moggie
28th May 2003, 18:35
If I read that article correctly, the earlier incident concerned gross mishandling by the crew who first allowed the aeroplane to stall (stick push?) and then applied massive, alternating rudder inputs to control the wing drop in the stall.

The fin did not separate and Airbus say that although it was cracked, it did not lose structural integrity.

Did it not occur to the airline that they might like to inspect something to a greater degree than the minimum, regulatory standard? Rules are rules and a minimum standard is set - but no-one says that you have to work DOWN to the minimum.

Remember, following the minimum schedule gave us the Aloha Airlines 737 convertible - so it's not one way traffic from Toulouse, Seattle does it too!

BigGreenPleasureMachine
28th May 2003, 21:34
Stop the presses: aircraft structure will fail beyond the ultimate load....in other news, two and two equals four.

PlaneTruth
28th May 2003, 22:19
Phoenix X,

During frequent visits to Edwards Air Force Base in California, crews would experience test flights by Test Pilot students where they would work the rudder stop to stop generating max yaw (yaw damper off) to visit the rudder limits. On an FCF (Functional Check Flight -post heavy MX) it was routine to get maximum rudder excursion stop-to-stop and then turn the yaw damper on. The book said the yaw cycles had to stop within 2 swings for the yaw damper to pass. Never lost any rudder parts.

These were in a 737-200 Advanced (T-43)

The aircraft reportedly barrel rolls quite nicely.

We also did stalls right through the stick shaker to the break on FCF flights. Flies like a Cessna 150 with minimal loss of altitude. More flap out = more roll. Every pilot should get the opportunity to experience a series.

PT

411A
28th May 2003, 23:19
Transistioned to jet transports on the B707-320B (advanced), then moved on to older 707 designs, -138B, -300 (JT4 powered) etc, where the yaw damper fitted was of the parallel type, not series. Had to be switched OFF on final.
Boot the rudder, big time trouble, the yaw occillations set up were someting to see...to be AVOIDED.
Somewhere along the line, the older guys who flew these machines retired, aircract designs got better, yet the same LARGE boots to the rudder which were avoided in older designs, apparently (with some companies anyway) became more-or -less standard practice.
The results were there for all to see, poor AirBus design or not.
The advice from the 'oldtimers' is as valid today as yesteryear...NO big boots to the rudder at higher speeds...period.

Anthony Carn
29th May 2003, 01:33
Fin design.

If I interpret the article correctly, it is saying that if a pilot uses incorrect flight techniques which exceed the certified/design loads of a fin, then the fin will be structurally damaged and may even break off. The fin did it's job by remaining structurally intact until it's design limit was exceeded. There is nothing wrong with the fin, therefore.

Stating the obvious, is'nt it ? Just like saying that a car engine has a rev limit of 7000 rpm, and being surprised that it then blows up when a driver exceeds 7000 rpm. Why should it be a surprise. Imagine the headlines "Engine blows up. Engine weakness found ! Engine a danger to road users !"


Flight techniques.

As I read the article, Airbus issued a reminder regarding unsafe flight techniques. That such techniques are unsafe was known to me when I started flying commercial aircraft over twenty years ago. Why, then, blame them if it's eventually proven that the same unsafe flight techniques caused the New York incident ?


It all seems ridiculously simple to me !

Covenant
29th May 2003, 01:38
Officials with manufacturer Airbus understood that losing a tail fin would prove catastrophic. Even so, they kept their concerns to themselves...

I'm sorry, but whatever the merits of the rest of the piece, an article that starts like this just loses any credibility with me.

As BGPM says: stop the presses! Airbus engaged in sinister cover-up over shocking news that aircraft don't fly very well without tail fins. Elsewhere, Ford Motor Company under investigation for suspected suppression of information about cars that stop running after being driven off a cliff. :rolleyes:

Phoenix_X
29th May 2003, 01:41
PlaneTruth,

Thanks for that -- it's good to hear that some rudders will withstand the force.

However, the point that they're not required to still stands, and that's where the real problem lies: Pilots mishandle the aircraft beyond its limits, and are in this rudder case not usually even aware that they're exceeding rudder design limits.

arcniz
29th May 2003, 04:20
If one steps back from this topic a few meters and looks at it from the (imagined) perspective of a lucid but mostly uninvolved observer, what seems very prominent is the reluctance of Airbus to put the facts about A300 tail strength vs rudder capability on the record. Although there are claims that the French told appropriate (FAA, CAA, etc ) authorities the bad news about the very tangible and ever-present potential for "partition de l'empennage" on the A300 , documentary evidence of this is not in view. IF statements admitting this problem were ever made by Airbus, they were certainly done at the level of a whisper, rather than a shout. It seems very clear that no methodical effort was made to document this unpleasant tendency in the training materials and in aircraft manuals that pilots rely upon. Certainly it would have been REASONABLE to do so, since pilots depend on these manuals for operational guidance and are trained to not make suppositions that go beyond the content of the manuals.

So - even if they were not covering up, the French seem to have been much less than forthright about this deadly flight characteristic.

Then there's the matter of the rudder limiter design - which seems to have some of aviation history's worst ergonomics when viewed in the context of the "partition de l'empennage" risk. It has been stated by multiple sources that the A300 rudder pedal limiter mechanism reduces "feel" and travel distance with increasing speed -- to the point where the breakaway force (to initiate any rudder movement) becomes nearly equal to the force required to achieve full travel of the rudder. Given that even the best-trained pilots will operate controls less gingerly when they realize deep down inside that they are losing control of the aircraft, this rudder actuation mechanism feature might well be labeled the "moyen pour l'ejection de l'empennage". The combination of the knowledge of the rudder pedal characteristics and the tail strength limits and the actual experience of Miami 903 would have further emphasized the importance of communicating these thoughts to all responsible parties - if Airbus were being genuinely forthright about the critical safety issues pertaining to the A300 in this sticky area.

Then there's the matter of the A300 yaw damper design, operation, reliability, and behavior in service. The design is novel in various regards. Novelty, by itself, is inherently neither good nor bad, except where problems are demonstrated by observed malfuctions. A fair number of anecdotal reports of oscillating A300 rudder and uncommanded rudder actuations have been cited here and in other public records, so one can infer that probably there is some regular incidence of 'hiccups' in the A300 rudder/yaw-damper systems. By itself, this would not necessarily be anbnormal or worrisome. Many aircraft have peculiar idiosyncracies and balky systems that require some special maintenance and attention. But the instabilities of the yaw damper system become much more ominous when taken in connection with the poor ergonomics of manual rudder actuation in the A300, the
ability of the big tail to tear itself off after n-many hard oscillations, the lack of very accessible technology and competence to ground inspect the non-metallic A300 tails for progressive deterioration from overstress, and the lack of freely available information about any of these to the people responsible for policy on safety and for day-to day aircraft operation.

Since Airbus management and their technical people are the only ones who had all of this information, we can expect that after the Miami 903 incident they would have undertaken some very intensive efforts to double-check the integrity and the possible failure modes of the yaw damper / rudder system, n'est ce pas? Did this happen? Have problems in the Airbus rudder / yaw damper system been diagnosed and resolved with the degree of seriousness appropriate to the proximity of catastrophe that accompanies each flight due to this pastiche of interacting weaknesses? Je crois non!

All the details behind this story should be made a matter of public record. We can hope the FAA will begin to do some serious digging - not to bury the problems but to uncover them. If Airbus does not cooperate fully, then FAA should pull their certificates.

bluskis
29th May 2003, 04:43
Ant Carn

If a car engine is liable to disintegrate above an rpm which it is infact capable of reaching, the normal practice is to limit the engine so that it cannot reach said revs.

There are some serious and fundamental, but certainly not advanced, engineering redesigns called for by both manufacturers.

411A
29th May 2003, 04:56
bluskis,
Older aircraft designs used a limiting device...it was/is called a "properly trained and experienced pilot" (or for engine/systems limitations ) "Flight engineer."

Imagine that....:rolleyes: :rolleyes: :sad:

Continuous Ignition
29th May 2003, 07:20
NTSB Identification: DCA97MA049 . The docket is stored in the (offline) NTSB Imaging System.
Scheduled 14 CFR Part 121: Air Carrier operation of AMERICAN AIRLINES
Accident occurred Monday, May 12, 1997 in WEST PALM BEACH, FL
Probable Cause Approval Date: 2/11/00
Aircraft: Airbus Industrie A300B4-605R, registration: N90070
Injuries: 1 Serious, 1 Minor, 163 Uninjured.
The flight was assigned an airspeed of 230 knots and cleared to descend from FL240 to 16,000 feet in preparation for landing at Miami. The FDR indicated that while the autopilot was engaged in the descent, the power levers moved from the mechanical autothrottle limit of 44 degrees to the manual limit of 37 degrees. As the aircraft leveled at 16,000 feet the airspeed decreased. The F/O began a right turn to enter a holding pattern and added some power, which stabilized the airspeed at 178 knots. However, the right bank and the resultant angle of attack (AOA) continued to increase, despite left aileron input by the autopilot. As the autopilot reached the maximum input of 20 degrees, bank angle increased past 50 degrees, and the AOA increased rapidly from 7 degrees to 12 degrees. At this point the stick shaker activated, the autopilot independently disconnected, the power was increased, and full left rudder was used to arrest the roll. The bank angle reached 56 degrees, and the AOA reached 13.7 degrees at 177 knots. The aircraft then pitched down, and entered a series of pitch, yaw, and roll maneuvers as the flight controls went through a period of oscillations for about 34 seconds. The maneuvers finally dampened and the crew recovered at approximately 13,000 feet. One passenger was seriously injured and one flight attendant received minor injuries during the upset. According to wind tunnel and flight test data the A300 engineering simulator should adequately represent the aircraft up to 9 degrees AOA. Unlike the accident aircraft; however, the simulator recovered to wings level promptly when the lateral control inputs recorded by the FDR were used. The roll disagreement between the simulator and accident aircraft began at 7 degrees AOA, and it appears that some effect not modeled in the simulator produced the roll discrepancy. Just prior to the upset the accident aircraft entered a cloud deck. The winds were approximately 240 degrees, 35 knots, and the ambient air temperature was approximately minus 4 degrees C. An atmospheric disturbance or asymmetric ice contamination were two possible explanations considered, but unproven.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The flightcrew's failure to maintain adequate airspeed during leveloff which led to an inadvertent stall, and their subsequent failure to use proper stall recovery techniques. A factor contributing to the accident was the flightcrew's failure to properly use the autothrottle.

Lu Zuckerman
29th May 2003, 08:47
I will most likely get pilloried for this.

At the time the A-300 and the A-310 were certificated in Europe the certification documents were pure FAA with a DGCA cover on the manual. None of the certification requirements were JAR and there was no European content in the technical design requirements of the FARs. When the two aircraft were certificated in the United States the only thing the FAA did was to verify the two aircraft could fly on a standard commercial flight in the USA and they also tested the aircraft handling qualities. They did not question the technical aspects of the design they simply accepted everything put forward by Airbus and the DGCA.

For those of you that defend Airbus simply because it is on your side of the pond do not be so defensive. I canít speak to the A-300 but I can on the A-310. Sometimes Airbus can not tell the certification authorities about a problem because they are not aware of the problem. When they do become aware of the problem they tell the certification authorities that the problem has been solved when it hasnít. When Airbus is not aware of a problem it is the fault of their suppliers. Even though the supplier is mandated to inform Airbus of a problem they do not tell them because they would have to incur the cost of modification. They would rather Airbus discover the problem and write a scope change to the contract requiring modification and then the suppliers would get paid. The problem is not discovered by Airbus because they did not follow their own procedures. If they did the problem would have been discovered.

When the FAA is made aware of the problems they are like a mule as it takes a swift hit between the ears with a stick to get their attention. When the do take action they have two managers fired but the design is never changed.

One of the suppliers discovered a severe design defect on a hydraulic component that could cause runaway flap or slat movement. In stead of notifying Airbus the made a quick fix on 17 shipsets and contacted the two airlines flying the A 310 telling them that they had improved the design and would at no cost replace the two units on each aircraft.

The flap slat computer was inadequately tested and the flap slat computer reliability had never been assessed and the design defect alluded to above still exists on all of the aircraft.

The airlines are not guiltless. Air Canada suffered an uncommanded retraction of the flaps on an A 320 during takeoff and almost lost the airplane. The certification authorities were never notified and as a result other operators of the A 320 were not made aware of the problem


:(

PlaneTruth
29th May 2003, 09:46
Phoenix X,

That is a bummer. You would expect as a pilot (I sure do) that the available flight controls should be capable of operation necessary to recover the aircraft (at least a reduced departure airspeed) --and not damage anything. My overriding question is: Why did these guys get on the rudder in the first place? I have encountered many wake situations and the aircraft has never yawed appreciably enough to warrant counter rudder application.

One note: I understand the AirBus rudder is alll composite unlike other vert stabs (Boeing for example) who have a metal spar to tie structural loads into the attach point. This AirBus design relied on metalic attach points but the majority of the structure is composite.

I have never had good luck trying to glue metal to plastic.

PT:ok:

PS I understand the original A-300 design was a Boeing concept that was canned. The design team leader decided it was such a good design, he defected with plans to AirBus. This from a former Boeing engineer.

stillalbatross
29th May 2003, 10:06
I still hark back to the rather spectacular losses that Boeing have had, the findings put forth by the NTSB and the total reluctance of Boeing to do anything that might upset their little corner in aviation. Did we see a front page article about the sh*t fights the NTSB had while trying to get Boeing to do some kind of fix of their 737, no we didn't. After the loss of two aircraft they still refused to believe the yaw was uncommanded. What about the grounding of the 747 while the centre tank was sorted? Airbus gets slammed because a crew stopped minding their shop and threw in rudder at the onset of a stall? What were they using for a brain?

Ignition Override
29th May 2003, 12:55
As for our "friends" at the FAA, were they not accused of practically hiding info from European sources regarding the serious problems suffered by the ATR-42 turboprop in moderate-severe icing conditions?

The point here is not where any plane is built-but can't regulatory authorities (at least in the US) "delay" notifying domestic airlines about whatever an aircraft problem consists of, as long as their documents are complete (in a legal sense), being unwilling to acknowledge problems with their certification conditions? Other than fatal accidents reported US media, which often include only the large aircraft in other countries with many people who perish onboard and/or on the ground. We seem to never read about incidents with foreign aircraft. Without "enlightenment" from the attorneys and papercrats who run our FAA, how would the American public even know about a plane which almost crashes in the Italian Alps (except for the rare bird on Pprune)? The FAA seems to be as motivated in this area as the Church bishops were in 655 AD to preserve Roman literature which explained how to cook garum pizza (with figs) for a party of twenty.

A tragedy occured in Indiana, allegedly because of the lack of initiative, or attempt to bury the info about aileron "snatch", if the term is correct. After the dead had been buried, our "Tombstone Agency" initiated more testing behind a water-spraying KC-135 and the manufacturer redesigned/enlarged the boots on the upper wing.
:ouch::yuk:

Anthony Carn
29th May 2003, 13:43
bluskis
If a car engine is liable to disintegrate above an rpm which it is infact capable of reaching, the normal practice is to limit the engine so that it cannot reach said revs.
If one limited the rudder authority to the extent that structural failure was impossible, then there would be insufficient rudder to control the aeroplane should an engine fail. There would be insufficient rudder to control the aeroplane during crosswind landings, unless the crosswind limits were reduced.

To employ your proposed solution would see aircraft failing certification in the single engine case, and a proportion of the then virtual reality flights cancelled due to excessive crosswind.

If one strengthened the rudder such that it could withstand any pilot induced loads, then one would be adding considerable mass at the rear of the aeroplane. For the aeroplane to then be stable, there would need to be an even more massive increase in weight at the front of the aero-plane. There would be a knock on effect, spiraling a massive weight increase. Fuel consumption would escalate and your ticket price would follow suit.

Then, don't forget, there's the wings - the elevator will allow a pilot to puill the wings off ! Shock horror ! Lets reduce elevator authority to prevent that -- OOPS ! Not enough elevator authority to control the aeroplane ! Lets strengthen the wings - impossible weight and cost spiral.

Then there's the undercarriage - that could be wiped off by a really rough landing ! Lets strengthen that ! Dohhh ! ..............

I think that by that stage in the "redesign" we've grounded the aeroplane ! It won't fly properly or safely now and it's too heavy for it's twelve (I guess) engines to push it into the air.


BTW, bluskis, falling (eventually) into the trap of arguing my engine revs analogy, you do know that commercial jet engines can be damaged by incorrect pilot handling, don't you ?

PlaneTruth
29th May 2003, 22:25
stillalbatross,

There have been nearly as many rudder incidents with the A-300 series aircraft as with the 737. Remember, the 737 is the most produced aircraft in commercial history. One takesoff every six seconds. There are 800 in the air at any given time throughout the day. If the rudder issue was a big one, we'd have seen many more accidents/occurences. Many of the purported rudder incidents were identified as yaw damper issues.

Of the two accidents you refer to, one was the Colorado Springs UA (-200) accident which is still indeterminent. The front range of the Rockies is known for violent rotors (horizontal tornados) and as of yet, they have no conclusive evidence the rudder had anything to do with the accident.

The more well known second accident was the USAir near Pittsburgh. While it appears the rudder PCU was made to malfunction by freezing it and then applying a blow torch to it, how this may have occured inflight is still pure conjecture. What is known is that the aircraft rolled and the copilot applied full rudder and full back stick right through the stick shaker. The controls remained that way until impact.

Boeing had to do their research like anyone else. It takes time.

If you want to point fingers at corporate mishandling or directly trying to influence the outcome of an investigation, you need look no further than the AirBus handling of the Habsheim crash. There's all the untidyness revolving around the incomplete control of access to the undamaged CVR and CDR boxes. The delivery took seven hours more than it should have and when the tapes were reportedly examined they had been spliced. The CVR and VDR to this day do not match up. Grab a copy of the Syndicat National des Pilotes de Lignes dated August 1990. It will blow you away. I got mine from a UAL representative who after trying to visit the factory in France to do an article on the new A-320 that UA was about to buy, was called in his hotel room by the head of Airbus and told, "to leave the country immeduately" --which he did.

Not to mention the legion of stories like one I witnessed myself here in the States where an A-320 (Northwest I believe at DTW in 1988) went around and the tower asked, "Where you going?" The crew responded, "We don't know." The aircraft entered holding at the MAP holding fix only to be recovered by a phone patch to France and the sequential pulling of 70 odd circuit breakers. Thank God for extra gas on that one.

How about the footage of the AirBus over France experiencing vast pitch oscillations --with passengers onboard, reportedly due to a software glitch.

I think Boeing's track record in being forthright during accident/incident investigations has been shown to be totally open and honest. The facts in AirBus' behalf clearly speak otherwise.

PT

lomapaseo
30th May 2003, 01:22
PT

You twist and misrepresent the facts to suit your opinions.

nuf said

PlaneTruth
30th May 2003, 04:59
IO,

"You twist and misrepresent the facts to suit your opinions."

And you sir evidently operate solely on emotion. You cast aspersions without any factual or creditable evidence nor any pretense thereto.

If you'd like to discuss any of the "facts" I presented that you think are incorrect, I'd be glad to.


Nuff Said.

PT

:ok:

Wino
30th May 2003, 11:38
The problem with the A300605R is the rudder load limiter.

If you do the controll check on the ground you will take about 80 pounds and 4 inches of travel on each pedal to get full travel on the rudder.

2 minutes after takeoff something happens and you put what you think is a measured and restrained 1.25 inch or so input with 22 pounds of force on the rudder pedals and what you think was an extremely restrained mild input turns out to put the rudder on its stops QUICKLY! It is pretty normal to put a 25 percent control input in on a flight control on a transport catagory jet. I do that every day with the elevator during the flare and often enough with the ailerons... What you thought was a similar restrained input in the rudder (something you don't often use) will scare and startle you leading to rapid overcontroll.

Its a trap for POI and is why the A300 600 leads the entire industry in loss of controls in the yaw access. Pretty impressive for such a small fleet of a couple of hundred aircraft.

Cheers
Wino

AhhhVC813
30th May 2003, 15:52
Ah, the old, we can't make it stop what it's doing stories. Legion in the minds of many people and all too unbelievable to be true. In the U.K. when the 737-300 EFIS turned up at Aer Lingus it was alleged that a go around commenced and the crew supposedly said they didn't know what it was doing. Cobblers!! These stories are great bar talk, but little else. As for having to reset 70 circuit breakers to get out of a hold, well that story has been around as long as the A320. It also supposedly happened to an A340, which also apparently, shuts its own engines down in flight, jettisons fuel when it feels like it, etc., etc.
Such garbage, it defies belief; and the more one hears it the funnier it gets, because, presumably, some people actually believe these things happen.
Above all, any pilot who is not capable of disconnecting an autopilot and flying an aircraft to where he wants it to go, if such alleged incidents as the hold one ever took place, should perhaps be in another job. Or I suppose conveniently, the autopilot was sulking as well and refused to disconnect.
Oh boy, I can't wait for the next story, you never know it might, just might one day be based around fact rather than fiction.

Buran
30th May 2003, 20:52
There was a program on british tv about Flight 587 and it mentioned the previous incidents of airbus fin loads going over the ultimate load. The transcript of the program is here:

http://www.bbc.co.uk/science/horizon/2003/flight587trans.shtml

Basically the AA pilots said they no idea that rudder reversals were possibly damaging, and in fact their training told them to use rudder when caught in wake vortices (which might turn a/c upside down).
Airbus said their recommendations are that ailerons are totally sufficient to correct any aircraft upset in a wake vortex (max bank angle 40 deg).

Also, the AA pilots said that they had no idea that the airbus has rudder travel limiters.
From my own experience in maintenance i know that our training went to great pains to explain the travel limiters and how it all works, i find it hard to imaging no-one would tell the pilots.
Then again, i know pilots tend not to get told (or want to know) all lot of things.
Can any A300 pilots out there let us know, were you told?

PlaneTruth
30th May 2003, 21:32
AhhhVC813,

I guess those guys in front of me just went around to log more time on the pay clock. That makes more sense.

Question for an AirBus operator (Wino?): Is it true that the Captain and The F/O each get a vote into the flight control system (along with several other computers) and if the computers decide your input is outside the laws of their programming perameters, they reject your vote?

I was under the opinion as expressed to me by AWest AirBus operators that the "autopilot" was essentially always on. The pilot merely opted for a direct input mode, which was still subject to override by the flight control computer and its programming. Is this correct?

Thanks for the first-hand information Wino.

PT

AhhhVC813
31st May 2003, 01:58
The A300-600 is not fly by wire, although the spoilers are computer controlled. The A320 is fly by wire, but the autopilot is the same as any other aircrafts. Take it out and within the parameters of the control laws you put the aircraft wherever you want it. The control system with the A/P out is the same as any other type, albeit the stabilizer trim is automatic and there is no feel feedback apart from the progressive spring in the sidestick.

PlaneTruth
31st May 2003, 07:35
AhhhVC813,

Thanks for the information. Still though, as per your explanation, the pilot input is still subject to approval by the Flight Control Computers and their determination of what is "in the envelope."

The reason I ask is due to puzzling accidents like the East African poorly executed go-around a few years back where the Captain flew into the ground. Evidently the GPWS doesn't override the Flight Control Computers when gear down and close to the ground. (Otherwise, how could you land?)

Thanks for your input.

PT

pom
31st May 2003, 07:53
The B737 has an autopilot mode called CWS, when you operate the autopilot through the yoke. The A320 flight control system is operated through the sidestick, but basically it is the same as 737 CWS. You cannot turn the autopilot off - the sidestick is connected to computers, not control surfaces and there is no manual reversion. During conversion, everyone practises landing the aircraft using thrust levers for pitch and rudder trim for yaw. It works nicely in the simulator. Anyone who has "flown" the A320 outside the design envelope will know that the aircraft will then respond in a random fashion to control inputs. Landing in gusty conditions it is not unusual to run out of elevator authority. In really bad conditions aileron authority will also go. The A320 is a good first attempt at fbw, nothing more.

:rolleyes: :rolleyes: :rolleyes:

PlaneTruth
31st May 2003, 23:00
pom,

Thank you, my point precisely. Once the aircraft Flight Control Computer decides to do it's thing, the pilots input is ignored. The pilot never flies the aircraft, but simply suggests to the computer what direction to go.

There were far too many stories early in the A-320 introduction describing the computers flying a profile far different than that suggested by the pilot. I am told that the cockpit video of the Habsheim crash clearly shows the throttles rammed full forward many seconds prior to impact. Why else would the engines not respond? Unless the pilot simply wanted to fly into the trees, there is only one other explanation: Computer malfunction.

The video of the A-320 pitching wildly over France horrified me, It has been shown here in the States several times and is chilling. Reportedly, it was a revenue flight with people on board.

Anyone out there have first hand knowledge about these incidents? Or others? Or are you willing to speak out?

I'll be the first to admit that Boeing has made it's share of mistakes in the past, but being less than forthright when questions arise about safety is not one of them. The hull loss records for the Classic 737 fleet are half that of the rest of the industry. Half! The 737 has hauled a number of people equal to the Earth's population -over two billion passengers. Given the sparse few accidents in it's past, I think anyone would have to agree it is a proven and safe design. Can it be improved upon? Surely and in many areas, the NG aircraft are light years ahead of the Classic airframes. I have flown Boeing 737 (200,300,500,700) equipment for over 17,000 hours and I have a list of features and design elements that I think could be improved upon. But, the basic airframe is marvelously well engineered. I have had the opportunity to fly at extreme ends of the envelope and have found no vices. We had instances of runaway throttles in the early days of the -700 (they are fbw. Big fun when your engine tries to go to takeoff power as you park at the gate!). A software problem was found and resolved --and that was 1997 software! Similarly, I am sure most of the early software for the fbw in the AirBus had some glitches. How can it not have had a few?

I am not berating the engineers at AirBus, the have made a remarkable fleet of aircraft in a short amount of time. I just think AirBus has been less than honest when issues about their equipment arise. The AA 300 crash is just the latest example. If history is any indication, there will be more.

PT

theblipdriver
1st Jun 2003, 03:52
The 737 has hauled a number of people equal to the Earth's population -over two billion passengers

the earth population is some 5 billions. so, you don't count china, india and some other well populated countries to this earth? ;)

i still prefer flying airbus, if just as passengers. if i have a look at the american hire-and-fire philosophy, i prefer the aircrafts i'm flying in to be built by skilled people, and not by those rapidly available on the labor market...

or how many airbus do YOU know of just exploded midair?

by,
al

cedarjet747
1st Jun 2003, 05:24
Has anyone looked at the animated reconstruction on the USA Today of the (commanded, I assume) rudder movements during the upset over the Atlantic in 1997? Just ignoring the fact that the incident began with a stall, the rudder movements seem pretty incidental to recovering the situation - indeed exacerbate it, and this was clearly the case over Rockaway as well. Where is the airmanship and professionalism in flailing away in such a random (and violent) manner on the rudder pedals? It's all very well to blame the French authorities, their US counterparts, composite materials used in primary flight surfaces et al, but the A300 and all other airliners are built to withstand (I believe) 150% of their max design load. In both the AA incidents this was exceeded fairly dramatically.

Three words come to mind reviewing these maneouvres and especially the control inputs in both incidents. Pilot Induced Oscillation.

wsherif1
1st Jun 2003, 06:00
AA 903 Pilot creates his own wind shear.!

The application of radical rudder inputs, besides bringing the wing up, also induces yaw transitions which create wind shear forces across the openings of the pitot-static sensors. The resultant low pressures cause erroneous flight instrument indications.

The pilot instinctively reacts to what he believes to be rapid altitude and rate of climb increases and a decrease in airspeed, by shoving the nose down, into a diving attitude, (Projecting the baby out of its mothers arms and the mother up against the ceiling of the aircraft, knocking her unconscious and breaking four of her ribs.!

The instantaneous acceleration, in the dive, at the rate of G, can exceed the aircraft's velocity for a safe recovery.! e.g. NWA 705, EgyptAir 990, United 585, USAir 427, UA 826, ATR 42 in Morroco, SilkAir MI 185, China Airlines 611, COPA Airlines over Tucuti, Panama, etc.!

Excerpt from NTSB letter dated January 21, 1998, "In many cases, as you correctly surmised, pilot reaction to turbulence, mostly inadvertent, does cause more problems than the jolt of turbulence itself."

Wsherif1

PlaneTruth
1st Jun 2003, 06:27
theblipdriver,

If you are referring to TWA 800, the jury is still out on that one. While the "O-Ficial" final report identifies hot tank fumes ignited by a wiring spark, I must tell you this:

I had an FAA checkride one day about two years after the explosion. The FAA examiner told me flat out he believed it was a missile. One of his life long friends and associates was a TWA MX technician assigned to the investigation and this gentleman had stated, without a doubt, it was a missile. Others in his area agreed but were censored. He said that in the middle of the metal bending outward (tank explosion mode) there was a clear pireced entry point where the metal was bent inwards, presumably by some object which struck the bottom of the aircraft. Now, that's pretty interesting. (Granted this guy is not an explosives/crash expert.) Furthermore, there are hundreds of witnesses from Long Island who reported seeing a streak of light seconds before the explosion. Perplexing indeed.

I am not a big fan of conspiracies but this one does leave a few untidy questions lingering. Do I think the tank could have exploded per the investigative report? It is a most plausible hypothesis. Still though, the fact that a trained mechanic who examined the wreckage believes otherwise is telling. Where the missile came from is unknown but a shouler launched missile could have been fired from a small boat not far off shore. I'm on the fence on this one myself.

Re:"the american hire-and-fire philosophy" Interesting point. As for the 2 Billion issue, I'll grant you that one. The number I quoted was a few years old and only dealt with the 300/400/500 family. :) Latest population update: 07/01/03 6,302,309,691 -all potential customers.

cedarjet747

I asked myself the same question: Why would you get on the rudders during a wake encounter. In my younger days I flew the "Four Fan Trash Can" (C-130H -"Props are for Boats") We used to regularly do minimal interval takeoffs (15 second separation between brake release). You'd have the aileron rolled to the stop and still get spit out of the tip vortices the other direction. NEVER did the aircraft yaw appreciably to cause "rudder flailing" or anything close to it. I have had chance to sample a 767, 747 and other wakes in my 737 and none of them required rudder application. Of course, I was above stall speed in each encounter.

In the '97 event, I think they were trying to aid the apparent aileron effectiveness with some help from the rudder. Problem is, deep into the stall all you do for the low wing when you stomp on the rudder is to accelerate the lower (stalled) wing and get it flying --at the cost of stalling the other wing. If you read the timeline, you can see that was the apparent outcome. The stop-to-stop flailing was clearly an act of deperation by a pilot far behind the power curve. (When we did stalls in the 737, we were warned : NO RUDDER after the break! The slightest yaw at the point of stall can launch you into a spin. A friend from 130's told me about a typhoon chaser C-130 from Guam which survived a 2 turn spin only to land with no wingtips: The outer fuel tanks had taken leave of their outer walls and the wingtips had departed the aircraft. ("It was like that when I got it. Really'")

My only quetion is, "Where the heck was the zoot telegraphed by "radar power" on the throttles? Took awhile to get the turbines wound up it seems. Very odd indeed.

Thanks for the good discussion gentlemen.

PT

:ok:

edit for population update

Ignition Override
1st Jun 2003, 11:54
Is there still some confusion out there about which Airbus types have fly-by-wire? Only the A-320/319 through the 330/340 types have the sidestick and strictly computerized inputs to all primary control surfaces (except some trim back-up?), although I've never trained on any Airbus (only jumpseated on the 300 and 320) :D .

theblipdriver
1st Jun 2003, 20:24
Hello,
I also heard of the theory of a missile. There were several aircraft which did some "strange things" in this region. TWA800, SWR111, Egyptair, etc. The only reason I don't believe the missile theory is the simple fact that the metal should be bent inward, if the explosion occured outside of the aircraft. Only few missiles have "hit-to-kill"-capabilities, such as the Patriot PAC3. Most missiles have proximity fuses, which will cause hundreds of holes in the fuselage. as for shoulder-launched missiles - they are infrared, so they will aim at the engines, and they have a max. altitude of max. 2-3 miles. the "streak of light" could have been fumes exploding a fraction of a second before the whole aircraft exploded.
In my point of view, a missile hit would simply be too obvious and therefor too difficoult to hide. would it be so difficoult to take some pictures of the metal bent inward and send it to the press? on the other hand - the USN did this before, like the iranian airbus some years ago :sad:

but time will hopefully tell...

cheers,
al

wsherif1
2nd Jun 2003, 08:30
Cause of TWA 800 crash: Aircraft Wake Turbulence in smooth air.!

Huge NTSB coverup.! No Missile.! NTSB removed essential data from oficial Flight Data Recorder (FDR) Chart.! Evidence proves TWA 800 experienced initial structural breakup 8 seconds prior to explosion.! FDR and cockpit clocks stopped 8 seconds after the NTSB's "End of Data time line".

Copies of before and after NTSB modified, FDR Charts, enlarged FDR chart, pictures of breakup damage prior to explosion and other irrefutable evidence available for proof.

If the true facts had been known we could possibly have saved those in the AA 587 accident.!

There are a number of other aircraft accidents, in which the NTSB has covered up the true facts, intentionally or through incompetence.

cedarjet747
2nd Jun 2003, 23:10
PlaneTruth, no sooner did you compliment us all for the good discussion when a load of old nonsense started coming up about TW800 and missiles. Pur-lease.

Just to add to the discussion about the questionable logic of 'getting on the rudders' after a wake encounter, I have to ask myself how good the aviating skills of some line pilots at commercial airlines actually are. Obviously that's a contentious statement at Pprune, but I just replied to another thread in here about cruise pilots, and I was reminded of an incident that was so close to being an accident that it will make your hair stand up. To recount briefly, an engine on a UAL 744 failed on rotation at SFO. The F/O who was flying used ailerons instead of rudder to correct the yaw / drift, which turned out be almost fatal since the amount of control input required lifted the spoilers along one wing, with an engine out on the other. Even with full power on the remaining engines, the aircraft decelerated as it was fully loaded with "freight, both self-loading and the good kind", plus full tanks for the 15 hour flight to Sydney. They drifted off course as they slowed down, heading right for a hill covered in highrise apartment buildings (invisible in mist). Things really started to go wrong when they got a stall warning and a ground proximity warning at the same time, and swooped over the residential district with only feet to spare, control surfaces all pointing in the wrong directions, unable to climb. The reports of hundreds of car alarms being set off is graphic enough to give you an idea how close they came to disaster (ATC thought the plane had actually gone in).

This is a well documented case, but the reason I tell it here (as well as giving us all a vicarious shiver) is to raise once again the problem of pilots becoming mere systems managers and not real aviators. The UAL pilot at the wheel above had performed a take off the previous week, but before that hadn't done one on a real 747 for a YEAR. Maybe a good pilot can become so flabby that a routine level-off can become a stall and a simple (if unusual) stall recovery can be dangerously botched; and maybe a simple wake encounter can become a catastrophe; and a simple engine failure can almost become a precursor to 9/11.

We're edging into a discussion about automation / duty time / etc here. But these AA situations and indeed the UAL incident as well have nothing to do with Airbus or composites or whatever (let alone missiles) and everything to do with well trained, able pilots in non-threatening, routine, elemental situations taking the kind of action that would get a PPL wannabe chucked out of flight school.

Thoughts?

PlaneTruth
4th Jun 2003, 11:14
Cedarjst,

Ahhh, The Untied incident!

I talked to a UA guy who had a buddy on the jumpseat (there were two jumpseaters reportedly onboard that day.) The hill was actually covered by one and two story homes. As the stickshaker was wailing the jumpeaters were yelling "PUSH!! PUSH!!" at the Captain who was flying but it was unclear whether they could see the close proximity to the hillside. Reportedly, some 70 windows were damage due to noise and jetblast along that street. Guesstimates were that the radar altimeter would have been below 100 feet had anyone noticed.

The first question is why didn't the guy use rudder. The United ALPA folks initially came out with an statement that United does their engine-out procedure differently than other airlines. When this hit the streets, they quickly changed their story. Obviously their method was inept. Or, their story was.

The main question I have is: Where was the Captain during the first 45 degrees of yaw off course? No doubt about it, he waited far too long to exercise his authority to take the jet.

I think there is a definite propensity to loose piloting skills as automation becomes the norm. At my company, we will never hook up VNAV because it requires that we stay in the loop. We have computer VNAV path information available in the form of a glideslope indicator but we actually hand fly the climbs and descents. It definitely keeps you involved.

Having only worked at this airline I cannot speak for others. I flew five legs today and six yesterday, for a total of 15 for the three-day. With that kind of frequency, you either get up to speed quickly or you are a dolt and we don't have too many of those here. I have heard from buds at other carriers (and observed on jumpseats) that many pilots first instinct is to start typing when things need attention. My first inclination is to punch off the autopilot and operate the plane.

Cheers,

PT:ok:

B767300ER
17th Jun 2003, 01:25
PlaneTruth...there were not 2 jumpseaters on board that UAL 744 flight, they were F/Os assigned to the trip as "International Relief Officers", or as UAL calls them---"bunkies". UAL normally assigns 1 Captain and 3 F/Os to their long-haul 744 flights (over 12 hours). These 2 pilots sitting on the jumpseats were members of the crew and rightfully spoke up during the GPWS terrain warning and subsequent stick-shaker activation. They helped save the aircraft, and are to be commended. For some reason, the Captain just sat there, until the airplane was under control and climbing away from the hills.

Any company with long-haul flights that staff relief pilots can learn from this incident. Pilots that never fly and have to re-qualify in the simulator are obviously rusty and over time lose their proficiency in skills such as engine-out climb.

Also, you referred earlier to the Air France A320 accident at Habshiem, in 1988, as a revenue flight. Not true. It was a fly-past for demonstration purposes to show off the new Airbus, and obviously resulted in a fatal accident. 3 fatalities and 27 injured, but all onboard were joyriding for the fly-past at the airshow.