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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 7th Mar 2009, 04:53
  #1701 (permalink)  
 
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Sorry for the delay in responding only been keeping half an eye on this thread as its been a bit of a shambles at the start.
rainboe:

I think software developers reading this thread, and people who have suddenly decided they could make software developers, should understand that far, far better software developers than you thought long and hard, and worked on this system design, and developed it in the light of experience, and have produced a system that has worked fine for all the world for 25 years.........except for 1 flight.
There is alot of truth in what rainboe has said here. As a programmer with 19 years experience across many industries I would expect you to shoot me down in flames if I told you how to fly and recover a plane as much as I would if you told me how best to write a bit of code. But thats besides the point.

Computers do make wrong decisions, but not often, it is the humans interpretation of the problem the computer is working to - if the parameters encountered are outside of those allowed for or expected then the computer will do the best it can given the information provided. People adapt alot easier than computers do to real time situations and can pull on experience - computers only follow a linear set of instructions. (For those interested in artificial intelligence pls start a seperate thread in jet blast to discuss as the result is the same).

My interpretation of what has been said so far is that the autopilot should have saved the day or at not least screwed up - computers dont think - they do - which is why we have the term GIGO (Garbage in Garbage out). Many a time a computer will function correctly but if the peripherals feeding it are feeding it garbage - a computer cannot make an educated guess based upon accumalted knowledge and experience - it can only do what it was instructed to do.

I personally have declined contracts in aviation, military and medical areas purely for this reason. I dont want it on my conscience to be blamed for an incident whereby the computer was relied upon where as it should have been used as a tool. Perhaps we can read this in me not being confident in what I do - or as I see it I am confident in what I write and test but not in how its implemented and sold (relied upon).

It is very important that you guys realise that all automatic aids such as the autpilot, gps, etc etc are just that in being aids. Hindsight is the only way parameters are going to be added to the software at which point test pilots are required to gain that hindsight and as sad as it is this incident could be an example of an unwilling test pilot adding to the knowledge pool. Yes it may sound to you like I am telling you how to do your job in some respects but hindsight to me tells me to enforce on to you as pilots to not rely upon systems as gospel as they rely on what was the understanding at best the last time the software was updated.

I would underline in any project we undertake, we can only simulate and facilitate your work load - but we are a long way from replacing you.

I do hope I have added value to at least some's understanding

regards

Jof
p.s. We must remember the computer is bound by the laws of physics also

Last edited by Jofm5; 7th Mar 2009 at 06:31. Reason: the sentence confused me on reading so nobody else had a hope ! lol
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Old 7th Mar 2009, 05:58
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CAMEL.

All professional pilots are very well versed in stall recovery techniques, however, there is no chance of complete recovery from a fully developed stall from the height in question at Amsterdam on a medium sized jet aircraft.
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Old 7th Mar 2009, 06:33
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Ams/mad

Interesting contrast between the way this investigation is being managed in comparison to MAD?
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Old 7th Mar 2009, 07:34
  #1704 (permalink)  
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I wonder how these armchair "experts" and purveyors of absolute garbage feel when the root cause of this accident is published?
Rainboe in post #61 stated:
So why not everybody just NOT post unless you have something positive or informative to say? Otherwise yet another important thread becomes unreadable. And PLEASE leave out the floral RIPs! We all feel sorry if there are casulaties, but this is not the place for tributes.
Even an alleged 737-800 pilot theorizes that perhaps the auto throttle was disengaged and went un-noticed by the crew.

No fuel was bandied around as well.

Press reported port engine separated in flight.

Dual flameout.

Aircraft flipped over before coming to rest.

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Old 7th Mar 2009, 07:44
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An absolute tragedy. Fatalities caused by the domination of automation `to make flying aeroplanes easier and safer`at the expense of retaining the generic ability to fly an aeroplane using good old fashioned human skill. This will not be the last time that we read about `carbon units` being killed by computers.
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Old 7th Mar 2009, 08:13
  #1706 (permalink)  
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Well, there's quite a lot to wake up to!

ant1 - I saw your Tech manual post at 1703 - it is still there. Mine too at 1705.

737av - remember MEL is company specific subject to the over-riding regulatory minimums. My post was RadAlt related. MEL for autothrottle is not relevant, I feel? I am not aware of the info you post on the No2 RA and autothrottle link.

Anyway, picking through the vitriol here, someone made what I think is a good suggestion about the autotrim, both in limits and in warning.

For cargun - I know of no effect of a faulty No1 RA on TOGA, based on the info available in out tech manuals. It should
a) select TOGA power
b) demand g/a attitude on the Flight Directors regardless of RA (as long as you are below 2000'RA which this one 'was')
c) over-ride the RETARD command issued to the A/T

Can you also tell me how I can look at that Synoptic ref you have posted?

Originally Posted by iceman
there is no chance of complete recovery from a fully developed stall from the height in question at Amsterdam on a medium sized jet aircraft.
- I disagree. Not saying it will be easy, mind!

Just to recap - it is looking pretty certain that any current aircraft with lowslung engines will NOT have enough elevator authority to overcome a fully aft trimmed tail with full power. The Boeing 737 upset recovery stresses that reduction of power, application of nosedown trim AND roll may be required to avoid excessive pitch up.

Worth restressing, I feel.
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Old 7th Mar 2009, 08:23
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Now, Reverend.....
Even an alleged 737-800 pilot theorizes that perhaps the auto throttle was disengaged and went un-noticed by the crew.
and your point being....?
In amongst the many posts, there has been some intelligent and informed comment, which has without doubt enhanced the awareness/perceptions of the many professionals who have both viewed and contributed.
Falling into the trap of 'dissing' everyone as armchair experts will deny you that opportunity.
I'm sure we'd all be interested to hear from your perspective, after you've acquainted yourself with the information available thus far.
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Old 7th Mar 2009, 08:24
  #1708 (permalink)  

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Jofm5,

My interpretation of what has been said so far is that the autopilot should have saved the day or at not least screwed up -
As I said previously, the choice here was pretty stark - see my previous Post http://www.pprune.org/rumours-news/3...ml#post4766442

If the logic had traded the GS profile for speed, the hole in the ground would presumably have been that much further from the threshold.

As you said, the machine did the best it could with the information provided. A bit like the A320 in Brazil...

One of the more subtle problems operators of sophisticated electronic systems have to deal with is knowing when to trust your senses and when to trust your instruments.

Disambiguating between the two is difficult because of what we're generally taught about their relative reliabilities, but it might just save your life.

It is sometimes difficult for the modern generation (myself included) to remember you are a Monitor not just another passenger...
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Old 7th Mar 2009, 08:38
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Profit Max wrote:

The change in radio altitude is not equal to the sink rate! Think of terrain - tall buildings, cliffs, hills, etc. If steep enough, this could lead to very high "sink rates" according to your calculation.
Right! I still think it should be possible to apply some kind of sanity check here. Anyway, getting rid of auto-retard in a single channel approach is IMHO the best solution (unless someone gives me a good reason to keep it).
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Old 7th Mar 2009, 08:43
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Originally Posted by SR71
As you said, the machine did the best it could with the information provided. A bit like the A320 in Brazil...

One of the more subtle problems operators of sophisticated electronic systems have to deal with is knowing when to trust your senses and when to trust your instruments.
That is why it is essential for the PF to be monitoring the raw data of the flight, so that he is effectively "mentally" flying the aircraft and "in the loop", even though the automatics are engaged. It is precisely when this "difference" occurs in the mind's eye of the pilot, that there must be immediate intervention by the pilot, by either correction to the automatics or reversion to manual flight, in order to preserve the safety of the operation.

In my view, there is just insufficient mention of pilot involvement in the required monitoring/feedback loop for this discussion to remain properly balanced.

Fly the aircraft !!!


JD


PS Incidentally, an excellent earlier post (#1751) by Jofm5 - well said indeed, I agree entirely

Last edited by Jumbo Driver; 7th Mar 2009 at 09:17. Reason: PS
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Old 7th Mar 2009, 08:52
  #1711 (permalink)  
 
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The change in radio altitude is not equal to the sink rate! Think of terrain - tall buildings, cliffs, hills, etc. If steep enough, this could lead to very high "sink rates" according to your calculation.
Not if you average over a few successive readings.

In any case we are talking about the final approach. High buildings and ground features like the Yosemite half dome will not come as surprises.
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Old 7th Mar 2009, 08:58
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Amsterdam - flat as a pancake!!!! Don't think there would be any terrain caused high rod's over the Netherlands. The highest terrain around is some tall dutch fella with platform clogs on!!!!
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Old 7th Mar 2009, 09:12
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An RA sends a radiopulse with a transmit antenna, it bounces off the ground and the atennuated pulse is picked up by the receive antenna, the time between those events is measured and the altitude equals that time*speed of light/2 MINUS ANTENNA HEIGHT AT TOUCHDOWN.

Given the exact value of the faulty altitude of -7 - -8 feet, does that value correspond to the receive antenna picking up the (strong) primary pulse without bouncing off the ground? The signal going straight from the transmit antenna into the receive antenna and the primary pulse being (mis)identified as a reflection?

It does not seem impossible to me that the transmit and the receive antenna are close together and some 2 meter from the ground... resulting in -7 - -8 ft... Does someone know the position of the antennas wrt each other and the ground?

Last edited by StuntPilot; 7th Mar 2009 at 17:45.
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Old 7th Mar 2009, 09:14
  #1714 (permalink)  
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Originally Posted by bobcat
Anyway, getting rid of auto-retard in a single channel approach is IMHO the best solution
For all the aces out there who want to be left to sort it out themselves, we should, in the interest of the fare-paying public, surely be catering for the 100's of pilots who cannot and who may allow the automatics to put them into a position where the recovery demands exceed their abilities.

Bobcat's idea is good in my book. I would go further and suggest that Boeing should dispense with the landing RETARD command and go along the AB route of an audio prompt. After all, we do not need auto retard, we can autoland without it and I can see no purpose in having it especially on single channel or manual flight.

Secondly, should we now be looking at imposing some further restriction on the amount an automatic system can trim nose up? In the case of a 737, stopping it earlier, at a point where we are still above Vss, and lighting the 'stab out of trim light' should give a tactile input that things are not right and require remedial action to continue stable flight. I don't know if this is also being looked at in the PGF accident by Airbus.
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Old 7th Mar 2009, 09:23
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BOAC I suspect there are many current NG pilots like myself who are finding the thread most informative, but do not have the time to contribute as much as some others.

I for one am not very surprised that the aircraft may well have been unrecoverable at the point at which it was attempted. 40 knots below VREF , combined with the back trim and pitch up moment from selecting high thrust and aircraft height make for an extreme situation. As you say it might just be possible, but from the performance of this crew up to that point very unlikely.

I am also not surprised that the Turks are trying to put as positive a spin on things as they can. Although I suspect that you would struggle to find any current 737 pilots who would place the main blame on the aircraft systems and design.

The open atc data is interesting but obviously needs validating. I await with interest a detailed description of the final approach and aircraft configuration. I am curious why the aircraft appears to have made such a shallow intercept of the localiser which led to a glide slope intercept closer in than ideal and from above the glide. The latter point is conspicuously absent in official reports to date so maybe things happened differently.

The aircraft required a considerable rate of descent to get on the glide while configuring and reducing speed at the same time. It is a reasonable assumption that the trainee must have been at a reasonably early stage in his training otherwise he would not have needed a safety FO. If this was the case then given what we now know it would have been prudent for the training captain to have taken control at an earlier stage. He certainly could have expected some foqa (flight operational quality assurance recording/think spy in the cab for those not familiar) busts at the very least.

I raised automation complacency in an earlier post. There was obviously other overconfidence. The crew had an impressive number of hours between them, although it would be interesting to know how many were on the NG. Finally I would add the old saying 'there is no such thing as a stupid question, only stupid answers'.
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Old 7th Mar 2009, 09:25
  #1716 (permalink)  
 
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BOAC,
The Bus still retards thrust to idle during an autoland, the retard call is just to remind you to position the thrust levers to idle, otherwise you will not get ground spoilers & autobrake.
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Old 7th Mar 2009, 09:27
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Originally Posted by BOAC
For all the aces out there who want to be left to sort it out themselves, we should, in the interest of the fare-paying public, surely be catering for the 100's of pilots who cannot and who may allow the automatics to put them into a position where the recovery demands exceed their abilities.
With the greatest respect to you, BOAC, I believe you are looking though the wrong end of the telescope.

Surely, we should be looking at increasing the ability of the "100's" you mention, so they can either keep up with what the automatics are doing or, alternatively, manage to properly deal with the consequences?

It's rather like saying that too many boys and girls are failing their GCSEs, so we will lower the standards ...


JD

Last edited by Jumbo Driver; 7th Mar 2009 at 09:44. Reason: quote inclusion
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Old 7th Mar 2009, 09:33
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I have a question for you Pilots.

This was a single channel approach. To me this means that they were briefed to do a manual landing. If they were going to do an autoland, then the second AP would have been engaged by the time of the RA subtle failure.
So what happened to the manual landing? I see no evidence that the AP/AT was ever disconnected.

If you were flying an auto approach to a manual landing, when is the latest that you take over? With this low cloudbase, would you wait until you can see the runway, or would that be too late. Would an autoland have been better?
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Old 7th Mar 2009, 09:39
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Ice man stated that there is no way to fully recover from a stall at the height in questionin AMS. Really?
Some years ago, whilst undertaking -800 conversion I was asked to fly this very same scaenario, Gear down, Flap forty, idle thrust and maintaining the glideslope, allowing the autopilot to trim the aircraft.
Recovery was initiated at the onset of the stick shaker following Boeing procedures, i.e. agressively apply FULL thrust, pitch to 20 degrees and then push to maintain the pitch.
The height loss was around 200 feet from the onset of stck-shaker to the initiation of a steady climb.
Whilst I admit we were primed and ready for the manoeuvre, it is not correct to say that you cannot fully recover from this situation.
Had the throttles remained at the forward stop and had the Captain been able to maintain a pitch of around 20 degrees, the results would have been very different, I'm sure. As it was, the design of the A/T, coupled with the 'minor' fault caused the power to be reduced yet again, just when they needed it most.
Even a partial recovery might have resulted in a lot lower rate of decent at impact.
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Old 7th Mar 2009, 09:41
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Where there is discord...

The hoary old Sullenbergers are surely right that adherence to the basic tenets of the profession would have prevented this accident. If there is one lesson to be learned that is it.

But given that every lesson learned may save lives, why not learn more than one lesson? The logic boffins are quite correct that the system handled a subsystem failure in an needlessly unhelpful manner.

There has been much discussion in the past of the risks of automation 'mode' errors. These, from a psychologist's point of view (my former field), tend to lead to 'cognitive misdirection' (if you doubt the power of cognitive misdirection go see an expert up-close magician).

Aspects of this incident bear comparison psychologically with such 'mode' situations. The system took two actions which it takes sophisticated cognition to make sense of - it annunciated 'gear' (directing attention to 'gear') and subsequently closed throttles (without directing attention to 'throttles'). Simply annunciating 'RadAlt Mismatch' would have caught the error upstream both systems-wise and human cognition-wise. That remains a salutary fact, whether or not it's ultimately considered to justify changes to current or future aircraft.
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