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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 8th Mar 2009, 14:34
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teropa, the supposed problem which made this aircraft difficult to control was that the auto trim (AP engaged) continued to trim nose-up to maintain a stable condition. Although the AP was in GS mode, the trim state is a function of airspeed, thus as speed decreased – (pitch control attempts to follow the GS) more nose–up trim would be applied. The trim might not have reached maximum as there is usually a small delay, but the setting appears to have been beyond what would normally be expected during a go around resulting in large (out of trim) control force in the nose-up direction.
This is not to say that the aircraft would be uncontrollable, nor with the added nose-up moment from TOGA thrust; a critical issue is that the force appears to required a two-hand push in an erroneous situation where the thrust levers also require to be held forward due to the failure to disengage AT – retard mode still active due to an erroneous RA1.
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Old 8th Mar 2009, 14:37
  #1842 (permalink)  
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Fred - no and yes.

Teropa - would you like me to post the initial Boeing MOM again (for the 5th time at least) or can you find that?

I suggest you also spend some of your Sunday wading through some of the 'BS' on the Airbus PGF thread too. There are some good answers to your question on trim there.
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Old 8th Mar 2009, 14:48
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Analysis of OpenATC ADS-B Data

Warning: I realise the OpenATC ADS-B reported data is entirely unqualified so the following analysis must be read in this context.

The above flight data is presented at equal data point time intervals. By taking the recorded Latt/Long positions I have calculated the distance travelled between successive data points along the flight track. From this it is then possible to calculate the aircraft groundspeed for each 15 second time interval.

Unfortunately, I don't know how to insert the graphs into this post so a description of how would be appreciated!

Unitl then, I can describe that the graphs show the calculated speed tracking an average of 65 kts slower than the reported ground speed and reaching a minimum value of 130 kts calculated (203 kts reported) at 9 nm before the accident site then increasing to 183 kts calculated (191 kts reported) at 6 nm before the accident where the calculated speed then matches almost exactly the reported speed from then all the way to the accident site.

Simply taking the Starting & Accident Point data yields a track distance travelled of 26.66 nm in a time of 585 seconds (9 mins 45 secs) giving a calculated average aircraft ground speed of 158 kts which seems rather slow to me?

IF the reported Latt/Long points and time stamps are correct (a very, very big IF) then this would suggest the aircraft ground speed was considerably slower than would normally be expected and would suggest something else untoward was happening way before localiser and subsequent glide slope intercepts.

Let me know how and I'd be pleased to publish the graphs.

PPL&Eng

Last edited by PPL&Engineer; 10th Mar 2009 at 08:13. Reason: Spelling Mistake
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Old 8th Mar 2009, 14:49
  #1844 (permalink)  
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I would certainly NOT advocate hitting TOGA in a low level stall! Nor do Boeing.
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Old 8th Mar 2009, 14:53
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PPL& - and other ADS-B'ers -appreciate the effort, but I really do not have much faith in this ADS-B thing as far as useful and reliable data is concerned. The FDR will have all the necessary info and tell the investigation if anything else went awry.

Many thanks to Johngreen for proof reading

Last edited by BOAC; 8th Mar 2009 at 15:20.
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Old 8th Mar 2009, 14:55
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RAlt.

Strange airplane: Dont have radio altímeter comparator light. Neither a Test sw
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Old 8th Mar 2009, 14:56
  #1847 (permalink)  
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I feel another wig order coming on.......................'Seconds out! Round Three'
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Old 8th Mar 2009, 14:58
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Pilots who allegedly have practiced recovery slow and in landing config describe a different picture (wrestling the column forward with both hands).

Fred Bound

They were on a Single Channel approach, no automatic GA available. And since TOGA seems to have been left alone, either the A/P untimely disengaged by itself or they disengaged it using one of the available methods: in this case it could have been pushing the column and trimming forward.
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Old 8th Mar 2009, 15:06
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BOAC
Fred - no and yes
Thanks.

Rainboe
You don't really think it's as easy as that do you?
No, I don't think it's easy. Nor do I expect that designing an aircraft to land itself is easy - but that was done 40 years ago and is considered normal now.

It's just that if the thrust/pitch couple, that has been mentioned dozens of times on here, is an expected result of the application of full or nearly full thrust, it is not unreasonable to expect that a modern aircraft control system might take it into account.

I'm not suggesting that TOGA was used here - just a question regarding the trim issue.

Last edited by Fred Bound; 8th Mar 2009 at 15:17. Reason: Added the last sentence
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Old 8th Mar 2009, 15:09
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question: On the NG does the AP automatically disconnect at stick shaker?
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Old 8th Mar 2009, 15:10
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Fred - can I ask you to try and sift through this thread as well? The a/c is easily controlled with full power in a normal go-round. It was the extreme trim condition which exceeded the elevator authority. As 'certified' for use, the 737 is perfectly safe and easy to fly. Boeing should not be expected to build a system to cater for what appears at this stage to be gross incompetence.

FE - I don't think so. Full automatic g/a remains available from a 2 channel stall, I believe, although it would be ****** exciting and as I said before, I would not encourage selecting TOGA to engage that!
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Old 8th Mar 2009, 15:14
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Thanks BOAC.
On the Embraer 170 it does. That's why I asked.
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Old 8th Mar 2009, 15:22
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Can't find anything saying it does, so it probably doesn't.
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Old 8th Mar 2009, 15:28
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Errare Humanum Est

The advent of daycare, child seats and airbags have combined in a significant number of hyperthermia fatalities where children have been left inside cars parked at work. The article includes discussion of the factors that result in an otherwise conscientious parent forgetting that their child is still in the back.

washingtonpost.com

The article makes for uncomfortable reading, but does a service in reminding us that an otherwise conscientious parent or pilot can make a fatal mistake.
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Old 8th Mar 2009, 15:38
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100% Please,
If you erroneously blame the radalt, then you should also erroneously blame:

The autopilot, for not being programmed to drop out when below a safe speed.
The autothrust, for not having an always-on alpha prot / alpha floor functions, and "Speed speed" callouts.
The displays, for not flashing a radalt discrepancy.
The dome light, for not flashing when peril is detected.
I have many thousands of hours in both seats of the NG (as well as the 320 series). I find the NG to be crude, nasty to fly, ergonomically challenged and generally a bit incapable during significant non-normals.
This is just about the worst bs Ive seen on this entire thread.It really annnoys me.The 737 is a fine workhorse with extremely good dispatch rates.The only reason that its not statistically the safest commercial jet in history is that pilots keep screwing the pooch.You really do have to know what you're doing when you fly it.
Boeing works on the KISS(keep it simple) principle.You,the pilot,must actually fly the thing,theyll help you out when and where they can but they wont hold your hand and if you screw up..dont call.

Dome light should never flash(more bs).I see no reason for including RA's in the comparator warning system(Baro alt,heading and AS are covered already..theyre your primary instruments).As for alpha floor,they have it but again its designed to be flown and controlled by the pilot.
Crude?You mean simple.
Nasty?You mean small flight-deck with no lunch table
Incapable during non-normal?You mean no ECAM checklist where you as a pilot dont actually have to think,reason and decide all on your own.

Back to topic.
Rainboe's comments,whilst correct,should not refer to crew directly or assign blame.The Dutch will work out what went wrong and the probable cause.Rainboe should not underestimate the little traps of automation that can confuse good pilots.The well-known ALT ACQ trap;on a GA if ALT ACQ is captured prior flap retraction the speed will revert to current speed in which case you could end up with flaps UP and not enough speed.Theres another stall scenario.Or if you approach FAF platform in VS and set missed approach alt in the window whilst still in ALT ACQ,the plane will maintain its VS rate and fly right into the ground.CFIT trap.
Personally,the failure to see RETARD instead of the normal MCP SPD on the AT FMA is minor although it would have spoken in volumes;a lot of people would do that.I think Airbus guys wouldnt because they rely more on what they see due feedback in limited channels.Its the failure to monitor A/S that is key.

Stall recovery is second.
i)How immediate was the response?Time in seconds from shaker-onset to recovery attempt.
ii)AT not disengaged?Why not?Startle factor..seat position.

EFSM(elevator feel shift module) hasnt been mentioned.Works above 100'RA with AP off and increases pressure to elevator feel computer to prevent pilots aggravating a stall situation.How much use?Would it have triggered considering the RA false reading?
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Old 8th Mar 2009, 15:53
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having read the thread.......

I don't know what caused this crash - no one does yet, maybe the investigators are close but this is a rumour network, so I think its reasonable to state some possibilities.

1. It wasn't caused by one thing - be it RA failure, pilot error, training flight. We know from life in general, and aviation in particular that a chain of events has developed - nothing broke that developing chain- not crew action, not computer, had that been possible this event would not have occurred.

2. To those who say training should not be allowed on commercial flights, ok, but think it through, the consequences of doing this include many more planes in the air, many of them empty, increased fares for pax, increased global warming for everyone - not acceptable.

3. Everything we do in life is a risk, our job as professionals is to minimize that risk. Note- I'm not suggesting we can eliminate the risk because we can't - the closest we can get to elimination of risk is to stay in bed all day, and even that poses the risk of hypostatic pneumonia.
To minimize risk we need to train (=practice) and make mistakes, remember we learn more from our mistakes than anything. The trick is to make these mistakes in a safe environment- be it simulator or real world.

4. There is a constant tension between cost and thoroughness - and we need to decide where on this continuum we place the acceptable norm. The "bean counters" will try to make us accept more risk in return for cost savings- that is their job, and they are good at it. However, they are not the ones sitting at the pointy end in the middle of a freezing dark night in the middle of nowhere - the pilot carries that burden. The "bean counters" genuinely do not understand - they understand statistics, graphs, spreadsheets, and use these tools to constantly shave off cost in the name of efficiency.
Aviation is very safe, look at the bean counters graphs that prove it. However, that 0.01% on their graphs are real victims in real accidents.
Eventually nothing more can be shaved in the name of efficiency.

5. The human/computer interface isn't quite right yet, at least not in all cases. Pilots initially learn to fly a simple plane with little in the way between the flight controls and the pilot-aviate,navigate,communicate. As we transition through complex singles to twins to jets we are taken further and further away from these basic skills, as we accept more and more help from automation, which most of the time gets it right. The real skill is in understanding how this technology can help us, and maybe more importantly what to do when it fails. If we can't do this we are in trouble, we may never know it because the holes never line up in the cheese, but when they do, the consequences are tragic.

Solutions - generally I think we need to look at increasing our understanding of systems and their failures-diagnosing them, and indeed treating them. If we don't diagnose the problem, then we can't treat it, and the problem will get bigger until it becomes fatal.
In this specific case, had the RA failure been diagnosed correctly, then someone on the flight deck should have known that the automation (AP/AT) was dependent on that RA and the likely consequence was a throttle retard for flare - diagnosis leads to treatment - do something about it - fly the plane. This link in the chain would have been broken, and the accident would have had a much greater chance of being avoided.

The workload at EHAM is a minor link in the chain, maybe lower workload and more time would have helped, but i personally doubt it.

Sadly, the investigation is likely to look for simple answers to complex problems, and the temptation is to blame the pilots-nice and neat, simple recommendations and no one has too much work to do to put the bigger links in the chain right.

I'll get my coat.
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Old 8th Mar 2009, 15:56
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aS BOAC told me, we're turning round in circles and I think this is the closest to the heart of the matter that we're going to get , for the moment, till new relevant information is available.
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Old 8th Mar 2009, 16:36
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theamrad

While we're at it, is there a real safety benefit from having A/T on the type of approach flown here?
Taking all the conditions here into account, weather, and the expectation that this was an autocoupled approach up to becoming vis - then the answer to that question should be blatantly obvious (there being several equally obvious reasons) to anyone claiming to be a qualified (esp. transport jet) jockey! Flying on AP with LOC and G/S and manual throttles (for reasons other than failure) would make for some interesting passenger experiences, esp' given the right weather - but then that was something which Rainboe indirectly mentioned earlier.
So we can perhaps add pax comfort to ease and convenience as reasons for using A/T on the type of approach flown. But I'm having trouble reconciling fairly castigating this crew for their apparent poor monitoring of speed and thrust setting, with a justification for using A/T based on the perceived difficulty of qualified crews to manually coordinate speed/thrust with an autopilot flown approach.
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Old 8th Mar 2009, 16:43
  #1859 (permalink)  
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MU - it is confusing, I grant you.

Firstly, it is easy to fly manual throttles on an autopilot coupled approach - it is just discouraged by operators. I do not agree with theamrad's statement. It requires more monitoring also but does not really adversely affect pax 'comfort'. The autothrottle takes away a lot of the effort but CANNOT be left alone without monitoring.
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Old 8th Mar 2009, 17:32
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I would certainly NOT advocate hitting TOGA in a low level stall! Nor do Boeing.
Other posters have said that although certainly a hard work, TOGA power can be used. Are some of you current pilots saying you would be able to use TOGA in a low level stall and still maintain control the aircraft, whereas others say that you could not use max power? Sounds like I might have to be careful with whom I book my next holiday.

OK. I am probably out of touch now having retired ten years ago. But it does strike me as bizarre that an aircraft can be certified if max (symmetrical) power cannot be used at ALL STAGES OF FLIGHT.

Standing by for the flak.

Last edited by jackharr; 8th Mar 2009 at 17:46.
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