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Continental TurboProp crash inbound for Buffalo

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Continental TurboProp crash inbound for Buffalo

Old 18th Feb 2009, 03:50
  #581 (permalink)  
ftp
 
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Not Adding Power;
Obviously we won't know this is the case until an official report is released. But it sounds plausible to me, how else did the A/C end up so slow?

When working as a FO, I've seen captains who have lot's of experience on other types do this a few times when they are new to an A/C. Especially if the A/C is configured with gear and flaps out. With a few other factors in the mix, it really isn't hard to only add power that would be appropriate for a clean configuration when leveling off.

I know of a case recently where the captain didn't even respond to the two challenge policy, and the first officer took control while the stick shaker went off. This was during the step down portion of an approach. That captain had +7000 hours on turboprops. I'm sure people make this mistake a lot more than we suspect.

Possibility of Severe Icing;
Could have easily happened. Forecasting icing isn't an exact science. But that A/C, at that altitude should have been able to handle almost any icing if the appropriate speed was maintained.

Good post Beafis
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Old 18th Feb 2009, 04:06
  #582 (permalink)  
 
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What are the split upper-surface flight controls just forward of the ailerons?
.
Why are they there?
.
lift-spoilers/dive-brakes/roll-spoilers? (a bit of both?)
.
When are they armed? When flap goes down?
.
Does the -300 or other earlier dash 8's have them (or are they just a -400 add-on?)


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Old 18th Feb 2009, 04:16
  #583 (permalink)  
 
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They're roll spoilers. On the 200 and 300 of which I'm familiar they all operate as roll spoilers below 140 knots and above 140 knots the outboard spoilers are deactivated. They're hydraulically powered and controlled from the captains control column (only relevant if the controls are split.) I'm sure someone will give the details for the 400 but I imagine it is similar.
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Old 18th Feb 2009, 04:17
  #584 (permalink)  
 
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Belgique;

If I can I will answer your first question ____What are the split upper-surface flight controls just forward of the ailerons?

Their air breaks.

Nice drawings.
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Old 18th Feb 2009, 04:18
  #585 (permalink)  
 
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NASA experimented with tail stalls in icing conditions with a turbprop as can be seen on youtube:

YouTube - 1 of 3, Aircraft icing loss of control
YouTube - 2 of 3, Aircraft icing loss of control
YouTube - 3 of 3, Aircraft icing loss of control

NTSB reports to date show circumstances identical with what NASA found.

The last video in particular is a salutary warning to all pilots.

IF the pilot can identify the tail stall AND know what it is AND be dexterous enough to respond in time AND be possibly strong enough to handle the controls AND have sufficient altitude to recover then a tail stall may be survivable.
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Old 18th Feb 2009, 04:28
  #586 (permalink)  
 
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Where are the trim tabs for the horizontal stabalizer?
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Old 18th Feb 2009, 05:30
  #587 (permalink)  
 
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There are no speed brakes on Q400. Spoilers act as roll/ground spoilers only. Stabilizer is fixed and elevator is trimmed via dedicated actuators - there's no trim tab.
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Old 18th Feb 2009, 05:31
  #588 (permalink)  
 
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hey all,

i dont usually add to these threads say it could be this could be that etc after a accident, but i have just watched a youtube video that i found since i am studying Aerodynamics at the moment and was wondering if you could think it could be tail plane stall due to ice...after watching all 3 youtube videos it makes sense that this accident could of been that. Have a look and see what you think

Also sorry if this has already be talked about


YouTube - 1 of 3, Aircraft icing loss of control

Last edited by satmstr; 18th Feb 2009 at 05:31. Reason: missed link
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Old 18th Feb 2009, 05:42
  #589 (permalink)  
 
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Beafis I think you nailed it. Especially with 1200RPM selected (likely if they encountered heavy turbulence in approach) the plane looses speed rapidly when leveling off without power added.

In such a configurationn the time between onset of stick shaker and onset of stick pusher is rather short.

How could the crew have overlooked the speed decrease? One theorie would be, that they both had the wing inspection light on and were looking backwards to watch their respective outer wing section shreding ice.

It is a bad habit found in many DH100 - DH400 Drivers. The ability to watch the ice buildup on the outer wings comes from the DH8-100 (no ice detector) and the old fear of ice bridgeing on the deice boots.

When the policy of wing deicing got changed (deice contantly ON when there is ice buildup) the reason for the wing inspection light disappeared. On the Q-400 there was never a reason but the necessity for Cross Crew Qualification with the older models.

Still many pilots get fascinated by that view of ice comming off their wing. In many thousand hours on DH8 100,300 and 400 I was never ever concerned about icing (and I have seen very heavy ice on approach into the valleys of the alps) But I was often concerned about a FO who kept supervising the right outer wing. Often you have to remind him/her to stay in the instrument scan and let the ice protection do what ist was commissioned for and what it proves able to do in hundreds of flights every day.

Last edited by maxrpm; 18th Feb 2009 at 06:49.
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Old 18th Feb 2009, 05:52
  #590 (permalink)  
 
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My first post here and unfortunately it is to link this article. Pilot Action May Have Led to Crash - WSJ.com
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Old 18th Feb 2009, 06:36
  #591 (permalink)  
 
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Icing

Robert C: "Meteorology is such an exact science, that "severe" icing 50 miles southwest of Buffalo can be discounted since another flight made it on the same path only 27 minutes later."

I respectfully suggest you are wrong on two points there. First, there is no way that meterology -- of all the "sciences" -- can be described as exact, or anything close to it. The reasons for that, and the myriad examples, are for another thread, but to summarise: Accurately predicting the specifics of movement, dynamics, forces, and the resulting actual conditions in the atmosphere is not something we are (yet) good at. Those who know meterology -- along with chaos theory, and how it applies to met -- will tell you that accurate specific predictions of icing (ie: amounts, locations, altitudes) is just not on (if you're interested search: "the butterfly effect" ). General predictions are the best that can be done; the best predictors by far are recent pireps.

Which brings me to point 2: The conditions encountered by another aircraft (even same type) 27 minutes later may indeed be relevant. But they may also be completely irrelevant. In my (way too many) years I have seen aircraft 3 minutes, or 5 mins, or even 10 miles, apart on the same route encounter entirely different conditions. Weather (especially "heavy" weather) is extremely dynamic.

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Old 18th Feb 2009, 06:47
  #592 (permalink)  
 
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Grizzled, try reading that quote with sarcasm, it works better and is how I thought it was intended.
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Old 18th Feb 2009, 06:47
  #593 (permalink)  
 
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From an article in the Wall Street Journal:

The commuter plane slowed to an unsafe speed as it approached the airport, causing an automatic stall warning, these people said. The pilot pulled back sharply on the plane's controls and added power instead of following the proper procedure of pushing forward to lower the plane's nose to regain speed, they said. He held the controls there, locking the airplane into a deadly stall, they added.
Pilot Action May Have Led to Crash - WSJ.com
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Old 18th Feb 2009, 08:19
  #594 (permalink)  
 
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...according to people familiar with the situation.
who here is familiar with the situation?
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Old 18th Feb 2009, 09:09
  #595 (permalink)  
 
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maxrpm

Am not sure I understand your thoughts about the wing inspection light. I think most of us, when flying an aircraft where it is possible to see the leading edge in detail from the cockpit, would very much like to do so. I do not see how you can describe keeping an eye on the wing in icing conditions to be a 'bad habit'?!

To think that because you have your ice protection systems operating you have nothing to worry about seems a rather dangerous attitude to me. Whilst the modern systems are very capable and well designed they are not infallible, and there are conditions out there which they will not cope with. The leading edge can be a very good early indicator of this and when you need to get the hell out of there.

As with most things, there is a time to be doing (or not doing) it though, and as you touch upon, at least one pilot should be monitoring the aircraft flight path at all times.

In many thousand hours on DH8 100,300 and 400 I was never ever concerned about icing
?
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Old 18th Feb 2009, 09:10
  #596 (permalink)  
 
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For those doubting that 2 'experienced' pilots, fully alert and with an a/c operating normally in good weather (let alone bad weather at night) could ever find themselves in a situation where they allow the a/c to slow to a potentially dangerous airspeed by forgetting to add power, allow me to impart some first hand experience.

I did exactly that, in a Q400, approximately 2 years ago, and until then, I would perhaps be equally scathing about such a scenario.

I was the handling pilot, flying a short inter-city sector on a pleasant summer day, and as we approached the holding point for the STAR we were flying, were instructed by ATC to take up the hold. Simple enough. Prior to this, the ATIS had been received, the brief given, and the STAR, hold and arrival programmed into the FMS. A/P was engaged.

As we entered the hold, descending to our cleared level at approx 800fpm, we were informed that the arrival runway had been changed. This necessitated a re-programming of the FMS. For some reason I do not recall, the non-handling pilot was having some difficulty doing so, and rather foolishly I allowed my attention to be distracted from monitoring the a/c and assisted.

Predictably, just as I did so, the A/P captured the selected level, levelled off and continued to fly the hold. No problem at all really, except for the fact that as there is no autothrottle, power was set at a level just above idle. The Q400 is a slippy beast, so it took a short while for the speed to decay significantly below 210kts, but once below perhaps 180kts or so, it decays very rapidly indeed.

As both myself and the other pilot were both heads down, leaning forward in our seats, the increasing deck angle was not immediately apparent. Fortunately, I happened to notice the lack of noise and a seemingly unusual attitude, and immediately recognised what was happening. I set climb power and the a/c responded instantly. The IAS had dropped to something in the order of 150kts!!!

From levelling off to reaching our slowest speed, the whole process had taken perhaps 30-60 seconds, and it took perhaps 10 secs to restore 210kts. It seems incredible looking back that I could ever be so dumb as to find myself in that situation, but it happened anyway. More worrying still is that until the power suddenly increased, the other pilot was equally oblivious to the developing situation.

For the poster earlier who enquired as to what the deck angle would have been, I'm sorry but I honestly couldn't say for sure (perhaps 8-10 degs), but it was sufficiently steep that after recovering the a/c we received an enquiry from our senior CC to ask if we had performed a go-around. She knew we had been descending (the cabin was already secure), felt the a/c level, then noticed a steepening deck angle and then a large application of power. In the cabin this probably felt just like a climb.

Both myself and my even more experienced colleague were very, very, very fortunate to have done little more than learn very valuable and basic lessons that day, but please don't sit there and tell me it can't, doesn't or won't happen in a multi-crew environment.
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Old 18th Feb 2009, 09:29
  #597 (permalink)  
 
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Otto

Good leason learned - and of course you're not alone. I've seen a similar situation develop (to about 175kts - should have been 210) on a busy base leg.. so there but for the grace of etc. etc.

Can quite see the possibility that distraction with the ice build-up could have been the killer in this incident.

Last edited by Loop... Hole; 18th Feb 2009 at 09:41.
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Old 18th Feb 2009, 09:51
  #598 (permalink)  
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Am not sure I understand your thoughts about the wing inspection light. I think most of us, when flying an aircraft where it is possible to see the leading edge in detail from the cockpit, would very much like to do so. I do not see how you can describe keeping an eye on the wing in icing conditions to be a 'bad habit'?!

To think that because you have your ice protection systems operating you have nothing to worry about seems a rather dangerous attitude to me. Whilst the modern systems are very capable and well designed they are not infallible, and there are conditions out there which they will not cope with. The leading edge can be a very good early indicator of this and when you need to get the hell out of there.
I think he means simply that if too much focus is put on monitoring a system that (in his experience) functions properly on its own rather than keeping more focus on a changing situation up front, it could be a very plausible potential reason for overlooking a speed decrease. Not unreasonable to call that a bad habit.

Obviously sans CVR this is all guesswork, but when a Q400 captain flying in the Alps chimes in to say that in his experience the aircraft itself handles icing well but crews are prone to displaying certain behaviour which might distract them, it seems worth considering.

Combined with Otto's anecdote two posts later which shows very vividly what can happen even in good weather and simpler conditions, this direction of thinking seems to be more probable than some of the more obscure mechanical or technical failures put forward in this thread.
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Old 18th Feb 2009, 10:09
  #599 (permalink)  
 
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dbx

I am not denying that it could have been a factor here (although all based upon speculation), and have already acknowledged that indeed it should not distract from flying the aircraft, as nothing should.

When the policy of wing deicing got changed (deice contantly ON when there is ice buildup) the reason for the wing inspection light disappeared
This implies to me that it is being considered not necessary to monitor the build of ice on the airframe if you have your de-ice systems turned on. THIS I find rather bemusing and concerning.
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Old 18th Feb 2009, 10:49
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But it does sound more and more like... 'Aviate, Navigate, Communicate' might have been lost in the moments leading up to the departure.

Am I right in thinking that there are really big differences between the shaker and pusher activation, and the behaviour in a genuine tail-stall? Such as other visual and aural confirmations of stall-recovery activation... it would be tragic indeed if ice/tail-stall 'thinking' had come to dominate, and a fairly straightforward recovery fought against.

The fact that 'speed & power increase' is warned against in some tail-stall recovery instruction also gives pause for thought...

The LHR/Staines Trident accident, whilst different in so many ways, was a case of 'disbelief, question, then fight the pusher' and included elements of poor airspeed monitoring coming close on the tail of configuration change (inadvertent).
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