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Originally posted by Gabriel
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Do you think they messed with the navigation beams again?Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut. -
[QUOTE.The flat deck angle (low pitch angle) can mean one of two things (or a combination of them).][/QUOTE]
Ok, Ill bite. What are those two things?
Or a "combination of two things" , still adds up to two things... let us in, Einstein. Do tell.......Comment
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Read the sentence immediately following that one, Einstein.Originally posted by TheKiecker View Post
Of course, as said, it could be a combination of those two things too: a bit of a steeper descent and a bit of a smaller AoA.The flat deck angle (low pitch angle) can mean one of two things (or a combination of them).
The pitch angle equals the flight path angle (which is negative in this case) plus the AoA angle, so the lower than normal pitch angle means that the approach is too steep or that the AoA is too small (the latter means that the speed is too fast).
Clear now, Einstein?
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The technical directive suggests that forward thrust was (inadvertently) applied instead of reverse thrust.
My instinct is that the effects of taking little short cuts taken here and there have joined together to produce this unfortunate outcome. Short Cuts may have been taken in any or all of these areas;
- design
- pilot training
- production of procedures, manuals & check lists
- quality maintenance and spare parts
- audits (of maintenance and operating procedures)
All of the above issues are more likely to occur in a corrupt state.Comment
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Sounds like TAM3054 in Brazil: http://en.wikipedia.org/wiki/TAM_Bra...es_Flight_3054Originally posted by tsv View PostYet another AD.com convert!Comment
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Short cut in design I really doubt. The Tu-204 is a well designed aircraft. Only the problem with aircraft in general, sometimes systems don't work flawlessly when in full operation.Originally posted by tsv View Post
We have new E-190 in our fleet and they still have toothing problems but they are effectivly taken care off with the correct action; ie maintenance/modification etc.
The main problem seems to be how to handle such an error. It's seems that despite warnings Red Wings did nothing to correct a known problem.Comment
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...Originally posted by gabriel
...Originally posted by kieker
Originally posted by the short versionLes règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.Comment
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That idea naturally comes to mind. However, the TAM accident was NOT a case of forward thrust (inadvertently) applied instead of reverse thrust.Originally posted by mawheatley View Post
In the TAM accident, one thrust reverser was intentionally disabled (MEL'd) according to procedures before the flight. The crew was aware of that to the point that they briefed this issue before landing. The procedure to disable the reverser is 1) to disconnect the switch that activate the reverser when the thrust lever is set into reverse, 2) to physically lock the reverser in the engine blocking it with a pin so it can't be deployed, and 3) during landing to set both thrust levers to reverse as usual. The effect is that the engine with the good reverser will act as normal, while the engine with the MEL'd reverser will do remain at idle. The disconnection of the switch and the physical lock of the reverser, together with the reverser software logic that that won't command an increase in power when reverse is selected until the reversers are physically deployed in the reverse position, ensures that forward thrust won't be inadvertently applied because the reverser failed to deploy or the crew forgot that the reverser was disabled. The operational procedure of using both reversers as normal is defined this way so the crew has no special actions to take. All these measures were implemented as corrective actions where some planes overran and crashed as the result of forward thrust being inadvertently applied with a disabled reverser or when the reverser failed to deploy.
However, in the TAM accident, not only that the crew didn't select reverse (as they should) in the engine with the disabled reverser, but they even didn't retard the thrust lever of that engine at 20ft, as per the normal Airbus landing procedure (where the plane calls "Retard, Retard!"). Why? We'll never know. The plane was not fitted with a brain recording device. However, I personally suspect the pilot knew about the previous accidents with the disabled reversers but was either not aware of the solutions that were made or was not aware or confident of the right procedure (the investigation found that while the "official" procedure in that airline was the right one, it was not being applied consistently across the crew, finding cases where it was applied correctly, others where no reverse was used, and others where reverse was applied only in the good engine), and that he had his mind set that he had to remember not to apply reverse in the "bad" engine, but that he was so focused on "not touch this lever in the landing" that he inadvertently went one step farther and he didn't even retard it.
Whatever the reason for this action (or better inaction), the result was quite bad: Not only that engine was left with the thrust that it had during the approach, but having both levers retarded is part of the logic that the plane uses to ensure that you intend to stop and not to go around, so having one lever above idle made that this logic was not fulfilled, so the autobrakes didn't activate (not a big problem), the spoilers didn't deploy (this IS a big problem, because a very significant bunch of the braking performance depends on the increase in weight-on-wheels and traction that results from extending the spoilers, and in this type the spoilers cannot be manually extended on ground), and that the autothrottle didn't deactivate so it kept increasing the thrust in the "bad" (non-retarded) engine trying to keep the selected speed.
So it was not a case of forward thrust applied when reverse was selected, but of forward thrust increased because the thrust lever was left in forward thrust.
I think it's unliekly that we are seeing the same case here, however I do wonder if the Tu-204 has all those provisions in place to prevent that forward thrust is inadvertently applied if the reverser fails to deploy when selected.
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I don't know all the facts but I agree - Design is the least likely issue here.Originally posted by ErwinS View Post
The spate of recent overuns on a relatively mature a/c is disturbing.
Pure speculation but I have to wonder if non genuine parts are being used. Alternatively how clean is their maintenance work?Comment
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There are 40 Tu-204 in service (39 now). 8 of them are operated by Red Wings (7 now). In less than two months, Red Wings overran an Tu-204 three times.Originally posted by tsv View Post
I don't have all the numbers to make the statistical analysis (and I don't know if I would be able to do it if I had the numbers). But at first, second, and third sight this rate of overrun incidents is statistically very significantly above the "typical" rates. For example, there have not been anywhere close to three overruns in two month every 8 airplanes in other airlines operating other types in the same time of the year and in similar geographical zones and weather)
This means that it's very unlikely the result of casual, random, chance, or luck factors. Rather, it seems to point out that either the airline, the type itself, or the interaction between these two factors (how this airline operates this airplane in particular) are in the core of the cause(s) of this accident.
In other words, the type (design), the airline (operation, training, maintenance) or both did it. I mean, did them, all three of them.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
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Crash investigations also examine possible human factor effects - including fatigue, rushing to meet schedules, physicals, and booze/drugs.Comment
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"Also" meaning "other that" what?Originally posted by Highkeas View Post
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so latest info is that failure of the left wow switch caused no spoilers, no wheel brakes on that bogey, and not only no reverse but max forward thrust when max reverse was commanded, not sure i like the way this system was designed. he was fast and landed a little long but still he went off at 215km/hr due to the system issuesmoving quickly in airComment
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So one landing sensor nullifies every way to stop the plane?Comment
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Did this airplane ger european and FAA certification?Originally posted by orangehuggy View Post
If the failure of one single sensor can cause this, I can't believe that it is comliant with such an issue. The plane must be protected against catastrophic single-point failures either by making them highly unlikelly (a chance less that 1 in 10 millions) or by redundance (a signle failure would not be catastrophic).
Furthermore, now the FAR requires that the reverers system has provision to prevent thrust from being increased until it is phisically verified that the reverse mechanism achieved the reverse position. So if the reversers fail to deploy (for whatever reason including a failed "on-ground" sensor) the thrust would not go beyond iddle even after selecting full reverse thrust.
While both are cases of significant forward thrust applied during landing, this accident is different from the TAM accident in Sao Paulo where the problem was that the thrust lever was left in a forward thrust position.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---Comment
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