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Turkish airliner crashes at Schiphol

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Turkish airliner crashes at Schiphol

Old 27th Feb 2009, 12:52
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Ankh asked a question

Originally Posted by Lost in Saigon
No, the tail breaking off would not cause the engines to stop.

There are even some examples where the engines continue to run after an accident has occurred.
However does the aircraft have G operated crash switches that might cause a shutdown?
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Old 27th Feb 2009, 12:58
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However does the aircraft have G operated crash switches that might cause a shutdown?
there are no such switches on the 738.
However - in the Amsterdam case you can be sure the engines shut down on touchdown.
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Old 27th Feb 2009, 13:05
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full power in a stall

Hello,

It was low on speed if we thrust the transponder data.

Energy profile suggests not enough power for whatever reason.

Yesterday a witness in the plain confirmed on the dutch news that after the drop (read: stall) full power was given until the crash. Could still be one engine, but power was heard.

If both engines were available pitch control is difficult at low speed due to the very high pitch-up momentum from the engines. Even worse if AP was on and trimmed for low speed.

A low power stall recovery at low altitude is not an easy thing on a 737. Control forces are high. The pith-up momentum of the engines can aggravate the stall condition.

More food for speculation?

Rgds
emjanssen (13 years 737)
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Old 27th Feb 2009, 13:12
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If full thrust was applied at impact, could the 'give' in the mud on the ground be enough to cushion the engines and avoid tip contact with the fan case? The fan blades look pretty much intact which doesn't square with what happens in a conventional high rotational speed engine impact.
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Old 27th Feb 2009, 13:17
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Agree?

What happened thereafter will be guesswork.
Agree and Agreed,

But some educated guesswork might suggest that as it seems we have a less than stable approach, Ochams Razor would point to that, rather than a mechanical problem, being the start of the causative chain.

Our SOPs require that the A/T are never fully disconnected. Yes, we do take out the autopilot, and announce it to the other chap, and also ask the other seat for "Speed Off" which requires speed to be deselected on the MCP. Following these actions, an alarm sounds for the AP disconnect, and the red-flashing warning light for A/T flashes. The Speed Mode is then shown as ARM. In these circumstances, thrust will return automatically when the actual speed falls below the selected MCP speed.
I can assure you that is not universal. We used to do that at Ansett, as well as A/P off, A/T on landings, but other Airlines I worked for discouraged both as Boeing does not reccomend it, their rationale being it can lead to uncommanded thrust increrases and therefore pitch excurtions near the ground.
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Old 27th Feb 2009, 13:20
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"The Speed Mode is then shown as ARM. In these circumstances, thrust will return automatically when the actual speed falls below the selected MCP speed."

And if it doesn't?
------------
protectthehornet -
None of the DC-8s I ever flew had autothrottles. I don't know of any.
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Old 27th Feb 2009, 13:24
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PJ2 - Thank you for your remarks. Could you please tell me the Post # referring to 'moving throttles'. Don't recall talking about them, especially with regard to the DC-8. Are you talking about auto throttles? We never had them on any model that I ever flew.
You're right about cockpit discipline. My contention is that the more automation there is, the more the pilots now-a-days rely on it and don't know what to do when it malfunctions and have forgotten how to "fly" an airplane. That coupled with having their heads inside and low pay and all the other things wrong these days, just leads to unfortunate results.
When those within the industry and those close to the Habsheim accident all agree with the report and how it was handled, I tend to go along with it even though "pilot error" probably played a big part. I've always thought it stupid to do these maneuvers in jet transports anyway. That's not what they were designed for.
BTW, I never had a problem with the 'short' 8 or the 'long' ones either. And, 'steam' gauges didn't kill anyone! Misreading perhaps, but that's a pilot thing, right? Being as how that's the only gauges I ever flew, I never had any trouble reading them for thirty years.
And while this accident doesn't invole a FBW aircraft, I don't think I ever said that they were "difficult or obscure" to fly. I'm sure they (FBW) fly just fine. It's when things are not normal that correcting the issue seems to become a problem.
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Old 27th Feb 2009, 13:26
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Markle: many thanks for the photo links. I wish I had looked at them last night, when I made some bad hypotheses because I did not know where the forward fuselage break was. Those posts of mine are gone now.

Wizofoz: agreed, I've worked on a few FMCs and autopilots and was always told that GS capture from above was a no-no . I was told the same when I did my IR.
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Old 27th Feb 2009, 13:29
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Now that the mode-S derived tracks are available, did more people notice that the intercept of the localizer happened after passing the Final Approach Fix? The FAF is 6.2 nm from the threshold, but the intercept happened at approx. 5 nm. And it seems they were some 300 feet high on the glideslope at that point. And still in the clouds.
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Old 27th Feb 2009, 13:32
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This "Speed Off" thing is NOT RECOMMENDED by mr. Boeing and I don't do this, nor is it allowed in our SOP's.
AP off = AT off simple as that.
and that said, I also prefer FD-off when flying manual.
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Old 27th Feb 2009, 13:45
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If full thrust was applied at impact, could the 'give' in the mud on the ground be enough to cushion the engines and avoid tip contact with the fan case? The fan blades look pretty much intact which doesn't square with what happens in a conventional high rotational speed engine impact.
The mud will not cushion the impact.

The one engine has crushed against the fan blades that's why they are not in perfect alignment with one another.

However the timing of the impact to the fan is critical when one considers that if the tail struck firstly then the fan rotor may have been stopped or slowed down by crushing of its drive turbine.

With only a couple of pictures we can't tell but the on-scene folks already know.

We have to face the fact that we don't have facts yet
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Old 27th Feb 2009, 13:52
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Rainboe, I think the reason for "capture from below" is to avoid capturing a false glideslope, read any ATP theory book for all you can eat on the subject.

Everyone seems to have their own ideas, but I´m sure there was a chain of events which caused this, not some singular cause.

Being Number 3 behind the aircraft in question on the ILS for 18R that day I can offer some insight regarding weather conditions

Cloud base could have been a factor, but unlikely given it was OVC/800´ I believe.

Visibility: was around the 4000m mark, with a TEMPO of 2500m, so again, possible factor but unlikely.

Icing: We had Engine and Airframe Anti-Ice ON, as we were in cloud for some time, however we had no signs of ice, either through the ice detect system or any visible icing whatsoever, and the temperature remained positive throughout our IMC approach and GA.

Winshear: Again at circa 1500´ it was on the nose at 20 knots, and reporting 210/10 on the ground, so hardly windshear territory I´m sure we can agree, again not ruling anything out, but unlikely.

I´m sure a multitude of factors came into play, and while the weather wasn´t BAD, it was murky with no distinct horizon, I could hazard a guess with other events going on inside the flightdeck, the weather wouldn´t be helping.

Regards

Atreyu
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Old 27th Feb 2009, 13:57
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.............

Last edited by Rainboe; 17th May 2009 at 17:41.
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Old 27th Feb 2009, 14:04
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The Air NZ incident with the false GS indication was not an aircraft system failure but a freakish one time (hopefully) maintenance issue at the airport IIRC .

ILS is a VERY reliable system , you can thrust it with almost 0 visibility.

YouTube - CAT III ILS Approach
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Old 27th Feb 2009, 14:07
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I´m sure many an imcompetent pilot has been called upon to capture a G/S from above as well. You´re missing the point, it's not good practice to capture from above, because of false glideslope capture risks. Not everyone is such a SkyGod™ as yourself and feel more comfortable doing it the old fashioned way i.e. G/S capture from below. (especially IMC, not IFR as you say sir, can you not fly Instrument Flight Rules in VMC?)

I think if you handflew an approach in IMC with a glidecapture from above then subsequently mess it up, it wouldn't be looked upon too kindly...

Atreyu
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Old 27th Feb 2009, 14:07
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GS capture from above

Rainboe: in addition to what Topcover said about false GS, if you try to capture true GS from above and do it with a high VS, you may end up in terrain.
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Old 27th Feb 2009, 14:13
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Late getting into this thread.

2 Things that got my interest.

The first is that the posts I have read seem to show some similarity to the 733 incident at EGHH a few years ago. High on the slope, levers at flight idle with A/T off (?), speed reducing, aircraft trimming up, TOGA pressed, thrust increasing, nose thrown up by increased thrust, pitch trim + forwards stick unable to compensate fast enough and the speed reducing further.

The second thing. The fuselage damage looks remarkably similar to G-BYAG at Gerona (LEGE) back in 199?.
Aviation Photos: G-BYAG
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Old 27th Feb 2009, 14:15
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BackPacker, re intercept before FAF

Yes Sir - it has been noticed.

PLS look at posts #579 and 600.
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Old 27th Feb 2009, 14:15
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Rainboe,

I was also a fan of "De-select speed" rather than A/T off, but it was catagorically prohibited in at least one airline I worked for.
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Old 27th Feb 2009, 14:21
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The reality is, in very congested airspace, being vectored, and often at high speed (180kts or greater) then occasionally your beautiful constant descent approach leads you to being slightly high on the glide. It has happened to me at AMS too - and not alot you can really do about it, since it is always difficult knowing exactly where you will be turned on base & intercept, and how fast/slow the controllers want you to be - and it varys at different times of the day, depending on traffic. To throw away an approach because you are 150ft to high at 6 miles would be a nonsense. If you are not stabilized by your specified, company height (1000 or 500 ft) then yes you should throw it away.
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