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Continental TurboProp crash inbound for Buffalo

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Continental TurboProp crash inbound for Buffalo

Old 19th Feb 2009, 21:33
  #741 (permalink)  
 
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The bombardier statement in post #753 describes the event sequence that I (and many of you guys) have expected. There are however a few items within it that puzzles me.

I would have expected the flaps 5 configuration earlier in the fatal speed-drop (even before). Even if they were using non-icing speeds the clean pattern speed would have been their reference and that should be about 160 kts. I definitely agree with all of you stating that a power increase could be neglected due to some distraction but I have much harder to see that happening while changing flaps configuration, twice (to flaps 5 and to flaps 15) since in my mind this more or less automatically triggers speed awareness. What do you think?

I would also have expected a different sequence of shaker/pusher and elevator input from pilot and at a slightly higher speed than 105 given that the incr. ref speed was on. At what time did the a/c performed nz=2g, my thinking is that this is in the initial pull-up (could otherwise be later just before reaching ground) and this also means that there is still air-flow to generate lift, however this would also increase drag and AoA causing the secondary stall. The point is that the shaker/pusher system with incr. ref. speed on could have triggered while there was still good control authority and the timing of the pusher in the sequence could be a design issue especially since I believe that 20 kts increment is far too much compared to the actual aerodynamic impact in most "normal" operation icing conditions.
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Old 19th Feb 2009, 23:12
  #742 (permalink)  
 
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A bit of history on tail plane stall

I don't have a direct source, but I've heard that Bombardier has basically said that the Dash-8 is not susceptable to icing induced tail-stalls.
Tail plane stall accidents have been occurring for decades, with several aircraft types showing particular susceptibility to the problem. DeHavilland Canada and Transport Canada got bit pretty bad by tail plane stall on the Twin Otter. There were a number of accidents and incidents after flight in icing where the tail stalled after selecting full flap. The problem was addressed on the Twin Otter, if I recall correctly, by a Flight Manual limitation against landing with full flap after flight in icing conditions.

Having learned from the Twin Otter experience, Transport Canada became the first major aviation authority to require certification flight tests to verify no susceptibility to tail plane stall. The test, as flown in Canada, requires simulated ice shapes to be installed, to create the worst case condition that would be found in FAR 25 Appendix C icing conditions. The aircraft is flown at VFE for each flap angle at forward CG, and extremely aggressive nose down pitch inputs are made, targeting 0.5g or lower. Typical tests use close to full nose down elevator, and the lowest load factor hits 0.2 or 0.3g. All Dash-8 models would have passed these tail plane stall tests.

Of course, we must keep in mind that certification tests only address conditions within the FAR 25 Appendix C icing envelope. There is good data to show that some parts of the world frequently have icing conditions that are much more severe than this (the area south of the Great Lakes is one of these areas). There are discussions to create an updated icing envelope that covers a larger percentage of the conditions that actually exist.

Based on all the info I have received, some of which is not yet public, I am certain that this aircraft did not experience a tail plane stall, and that the icing conditions were not a direct cause of the accident, except possibly as a distraction.
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Old 20th Feb 2009, 00:45
  #743 (permalink)  
 
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Under the USA NTSB Party System

Members of the assiting parties may act as advisors and may not make statements external to the NTSB about findings in the investigation.

This does not prevent these parties from fulfilling their obligation to advise in the safe operation of the product outside the investigation.

Some of the words I have seen associated with the parties do not seem to fit this modus operandi and must be taken with a grain of salt that they are "planted" stories external from the official investigation.
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Old 20th Feb 2009, 03:26
  #744 (permalink)  
 
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Originally Posted by khorton
Based on all the info I have received, some of which is not yet public, I am certain that this aircraft did not experience a tail plane stall, and that the icing conditions were not a direct cause of the accident, except possibly as a distraction.

Thank you for your input.

I agree, that in fact, icing had no part in this accident.
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Old 20th Feb 2009, 09:08
  #745 (permalink)  
 
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This accident ASN Aircraft accident NAMC YS-11A-300F N128MP Lafayette-Purdue University Airport, IN (LAF) seems to me to be similar to the accident in question.

That said, I'm making no judgement on the cause of the accident in question. That is the NTSB's job.
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Old 20th Feb 2009, 09:41
  #746 (permalink)  
 
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The only comparison is that there has been TALK about icing being a factor in this one (not proven yet).

But the one you're referring to was at 400 ft and already had flap 35 and speed was not abnormal, so many differences....
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Old 20th Feb 2009, 11:13
  #747 (permalink)  
 
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So why does a pilot fight a stick-pusher?

Comment from Flight Safety, "we only rent out the flight simulators, Colgon uses its own instructor and syllabus." Seems like everyone is now distancing themselves from this accident.

I heard that the Captain had about 3,200 flight time, I'm assuming it's total time. In my opinion that is note a lot of experience. The human toll of this accident is awesome. 50 families are affected by this and their lives will never be the same. One lady was doing humanitarian work in Africa and making lives better over there.

Perhaps this accident will put an end of the old line, "pilots are overpaid."
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Old 20th Feb 2009, 11:23
  #748 (permalink)  
 
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Originally Posted by ATPMBA
So why does a pilot fight a stick-pusher?
Good question. Possibly because he didn't realise it was the stick pusher.

Edit: On the assumption that the Q400 stick pusher is similar to the Q300 pusher (someone can confirm if this is the case), if he doesn't want the stick pusher, i.e., he believes it's activated in error, he doesn't need to fight it, he can de-power the stick pusher with a button on the glare shield, or have the PNF do it.

Comment from Flight Safety, "we only rent out the flight simulators, Colgon uses its own instructor and syllabus." Seems like everyone is now distancing themselves from this accident.
That's a fair comment from Flight Safety. Our company has used Flight Safety simulators in the past but Flight Safety themselves had nothing to do with the training, they didn't even own the sim.
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Old 20th Feb 2009, 12:34
  #749 (permalink)  
 
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The spoon-fed data the NTSB has released is a bit confusing and I would expect that we don't know the exact sequence of flight dynamics.

I think the pitch up prior to the stick pusher could have happened even without the PF over-riding it. If the crew called for max/firewall power at the stick shaker when they became aware of the low speed situation, the plane would pitch up quite quickly with no manual inputs. This is because the aircraft would have had significant nose up trim to maintain the slow speed and now the autopilot is kicked off. With the combination of increased prop wash over the elevator and the aircraft literally "powering" it's way to the nose-up attitude, I can easily see the aircraft attaining a 31 degree nose-up attitude prior to stick-pusher activation....and all this without any input from the pilot.
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Old 20th Feb 2009, 13:04
  #750 (permalink)  
 
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Here's an interesting and diverse list of turboprop icing incidents and/or accidents in chronological order (starting from 1990). I think it illustrates some of the NTSB's evolved thinking on icing and turboprops.

2006
LAX06IA076
2002
DCA01MA031
2001
FTW01IA051
1997
DCA97MA017
1996
SEA96IA074
FTW96IA045
1995
LAX95IA128
1994
DCA95MA001
CHI93IA140
ATL94IA092
1993
DCA93IA027
CHI93MA061
1991
DCA91MA019

Last edited by Flight Safety; 20th Feb 2009 at 13:48. Reason: With time to read them, this list appears more useful than I thought.
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Old 20th Feb 2009, 13:19
  #751 (permalink)  
 
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Chealander Leaving Ntsb At End Of Month


FOR IMMEDIATE RELEASE: February 20, 2009
SB-09-08
MEMBER STEVEN R. CHEALANDER TO LEAVE NTSB AT END OF MONTH
Washington, DC - National Transportation Safety Board Member Steven R. Chealander has announced his resignation from the Board, effective February 28.
Chealander has been a Board Member since January 3, 2007. During his tenure at the Board he was the Board Member on scene for three major transportation accident investigations - a mid-air collision between two news helicopters in Phoenix, Arizona in 2007, the crash of a corporate aircraft in Owatonna, Minnesota in 2008, and last week's crash of a turboprop airliner near Buffalo, New York.
Member Chealander testified before the Texas State Senate in April 2007 on sobriety checkpoints, and before the Tennessee House of Representatives in October of that year on drunk driving laws. In April 2008, he testified before a subcommittee of the United States Senate Commerce Committee on the NTSB's most wanted aviation safety issues.
Before coming to the Board, Member Chealander was a fighter jet pilot for the United States Air Force, at which time he was a member of the famed U.S. Air Force Thunderbirds, and was a captain for American Airlines.
In his letter to President Barack Obama yesterday, Chealander said, "I wish you and your administration well as you lead America through the challenges facing this great Nation of ours... It has been one of the most rewarding experiences of my professional life to work with the professional career employees of the NTSB, not to mention the four other dedicated Presidential appointees that constitute the Board."
Chealander has accepted a position in Miami, Florida with Airbus Americas as Vice President, Technical Training.

- 30 -
NTSB Press Contact: Ted Lopatkiewicz
(202) 314-6100
[email protected]

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Old 20th Feb 2009, 13:27
  #752 (permalink)  
 
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Capt. Chealander Leaving N T S B

************************************************************
NTSB PRESS RELEASE
************************************************************

National Transportation Safety Board
Washington, DC 20594

FOR IMMEDIATE RELEASE: February 20, 2009
SB-09-08

************************************************************

MEMBER STEVEN R. CHEALANDER TO LEAVE NTSB AT END OF MONTH

************************************************************

National Transportation Safety Board Member Steven R.
Chealander has announced his resignation from the Board,
effective February 28.

Chealander has been a Board Member since January 3,
2007. During his tenure at the Board he was the Board
Member on scene for three major transportation accident
investigations - a mid-air collision between two news
helicopters in Phoenix, Arizona in 2007, the crash of a
corporate aircraft in Owatonna, Minnesota in 2008, and last
week's crash of a turboprop airliner near Buffalo, New York.

Member Chealander testified before the Texas State
Senate in April 2007 on sobriety checkpoints, and before the
Tennessee House of Representatives in October of that year
on drunk driving laws. In April 2008, he testified before a
subcommittee of the United States Senate Commerce Committee
on the NTSB's most wanted aviation safety issues.

Before coming to the Board, Member Chealander was a
fighter jet pilot for the United States Air Force, at which
time he was a member of the famed U.S. Air Force
Thunderbirds, and was a captain for American Airlines.

In his letter to President Barack Obama yesterday,
Chealander said, "I wish you and your administration well as
you lead America through the challenges facing this great
Nation of ours...It has been one of the most rewarding
experiences of my professional life to work with the
professional career employees of the NTSB, not to mention
the four other dedicated Presidential appointees that
constitute the Board."

Chealander has accepted a position in Miami, Florida
with Airbus Americas as Vice President, Technical Training.


- 30 -

NTSB Press Contact: Ted Lopatkiewicz
(202) 314-6100
[email protected]







************************************************************
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Old 20th Feb 2009, 13:35
  #753 (permalink)  
 
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Did the FDR capture the control inputs?
The a/c went through some wild pitch and bank movements and I was wondering if the pilot control movements were sync or was he fighting it.
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Old 20th Feb 2009, 13:50
  #754 (permalink)  
 
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Did the FDR capture the control inputs?
Yes it did, and we await that information.
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Old 20th Feb 2009, 15:43
  #755 (permalink)  
 
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On the assumption that the Q400 stick pusher is similar to the Q300 pusher (someone can confirm if this is the case), if he doesn't want the stick pusher, i.e., he believes it's activated in error, he doesn't need to fight it, he can de-power the stick pusher with a button on the glare shield, or have the PNF do it.
It's been a while, but I'm positive the Q400 also has a stick pusher cutout pushbutton on the glareshield.

Whilst you raise a fair point about being able to use the cutout, I'm not convinced that in the likely circumstances at play here, that doing so would have achieved anything more beneficial.

Unlike a situation flagged up by a system problem, where the cutout pushbutton is used as part of a checklist procedure, where the stick pusher suddenly fires and catches the crew unaware, it is completely natural to use force to override it as a first instinct.

I would be fairly certain that the Colgan crew were not expecting or prepared for the stick pusher. Add to that a presumably dark night, and equally likely a dark cockpit, combined with that horrible moment of "what the ****?" and you have a situation where asking either pilot to go fishing about trying to hit a small pushbutton on a badly illuminated glareshield is not a great option.

I don't know what the panel illumination was like on the 300, but on the 400 it was extremely poor. Even at max illumination, the overhead panel in particular was almost unreadable, and I would assume that the Colgan crew had no additional illumination (such as storm lighting or dome lights) to assist with an instantaneous identification of glareshield pushbuttons. Remember, this is a pushbutton that most pilots will never use outside of the simulator, and so there is no 'muscle memory' associated with finding it in the same way as the every day selections on the panel.

It is also worth considering as one of those hindsight issues, that had this been done (a non-standard, non-checklist, unbriefed action), what view would the investigating authorities take if there had still been an accident, but with some survivors? I'm not convinced they wouldn't try to find a way of hanging the crew out to dry.
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Old 20th Feb 2009, 16:04
  #756 (permalink)  
 
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I'm not suggesting they should have pushed the shutoff, just that if they had it would be an indication of a deliberate planned action. With them not pushing it, it gives more support to the (pretty obvious) view that they were reacting to a rapidly developing situation. You're right that it's difficult to see in the dark. When we were playing with it in the sim I pushed the EGPWS inhibit instead which wasn't much use at all. So yeah, even if they recognised the stick pusher and thought it was operating in error they probably still wouldn't have gone for the shut-off switch.
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Old 20th Feb 2009, 16:12
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Quote:
Did the FDR capture the control inputs?

Yes it did, and we await that information.
I don't feel comfortable about this lack of information in the midst of the press all over the crew error reports being released under the table by folks close to the investigation. We've got to stop holding kangaroo courts in the press and do technical facts first and analysis second.
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Old 20th Feb 2009, 16:32
  #758 (permalink)  
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Comment from Flight Safety, "we only rent out the flight simulators, Colgon uses its own instructor and syllabus." Seems like everyone is now distancing themselves from this accident. My bolding

Not least of all the head honcho of Continental, who in a broadcast statement, repeatedly mentioned the operators name. My feeling then was that if you contract another operator to take your passengers, you have to carry at least a proportion of the can. A large proportion.

DHC6tropics said: (sorry, but I don't feel taking a small part out of context would be right. This I feel is quite an important post.

I think the pitch up prior to the stick pusher could have happened even without the PF over-riding it. If the crew called for max/firewall power at the stick shaker when they became aware of the low speed situation, the plane would pitch up quite quickly with no manual inputs. This is because the aircraft would have had significant nose up trim to maintain the slow speed and now the autopilot is kicked off. With the combination of increased prop wash over the elevator and the aircraft literally "powering" it's way to the nose-up attitude, I can easily see the aircraft attaining a 31 degree nose-up attitude prior to stick-pusher activation....and all this without any input from the pilot.


Very significant I would think. However, going along with the original thoughts for a moment:

On the issue of fighting, or even disabling the Pusher AFTER the event, I don't think it matters very much. Having trained on the real aircraft, (1-11) for some years, I found the push quite relaxed - and once it had pushed, you had control again. I'm assuming the Q doesn't hold the stick forward for a given time.

Of course, we weren't near the ground, so the pressure to 'un-push' was nowhere near as great. But at the end of the day, it really did just shove the nose to where it needed to be. My understanding of the P.I. (Stains) accident is that the controls were pulled back several times without a hope of the aircraft gaining height.

Yes, the average pusher can be overridden, but to do so will surely negate the function of a vital safety device.
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Old 20th Feb 2009, 17:40
  #759 (permalink)  
 
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Loose Rivets

As I posted yesterday (or 2 days ago), the Q400 stick pusher operates with 36kg of stick push force, it requires 36kg of reverse pressure to stop this push, and then a further 30kg of constant pressure to override the pusher clutch.
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Old 20th Feb 2009, 17:55
  #760 (permalink)  
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Trying to acquire or maintain the "correct" Pitch against a mechanical pusher, must be quite a feat. If the Pitch up was Captain's success at overcoming the Push, he may have been pushing rudder unequally to gain footing, hence the Roll and re-Roll. (Pull with your Hand, Push with your feet). If he removed his feet to place them on the floor, and lost purchase on the SP, this may explain the Nose Down. Seventy odd pounds maintained while seeking the Button to defeat and a foot rearrangement in a Dark (fairly new) cockpit, having been attentive to LOC, nav. Tower freq switch, etc. etc. God Almighty.

Last edited by airfoilmod; 21st Feb 2009 at 00:44.
 

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