New FACTS from NTSB on Colgan 3407
02-16-2009, 06:47 PM
#111
APC co-founder
Joined APC: Feb 2005
Position: B777
Posts: 5,853
From the first PM message I sent to you:
Thanks for the note although I closed your thread because it was going nowhere fast and only creating work for the moderators. It was apparent that you weren't going to get the answers you were after.
I know only one user on this forum who is active on the current Colgan accident and there is no way he would post here while the investigation is active. Everything else is a guess.
I know only one user on this forum who is active on the current Colgan accident and there is no way he would post here while the investigation is active. Everything else is a guess.
If you have the ear of commercial news networks, I hope you'll urge them to listen to what the NTSB says during the investigation, and not to speculate on what they don't say. Not jumping to conclusions is the hardest part of any investigation...
...I've learned that physical evidence is somewhat straight forward to read, contributing factors are much more elusive and take significantly longer to identify.
...I've learned that physical evidence is somewhat straight forward to read, contributing factors are much more elusive and take significantly longer to identify.
Last edited by HSLD; 02-16-2009 at 07:04 PM.
02-16-2009, 06:48 PM
#112
Line Holder
Joined APC: Feb 2009
Posts: 51
My thoughts on this are.
An airfoil [in this case the horizontal stabilizer] can be stalled in either direction. [think inverted spin entry]
When the flaps are deployed the aircraft will seek it's trim speed and wants to pitch up.
The horizontal stabilizer would than have to generate an upward component of lift to push the nose down.
Even though an increase in airspeed would increase stabilizer authority it would also increase the pitch up tendency the stabilizer had to counteract.
When the stabilizer stalled the aircraft nose pitched upward. The main wing would than stall.
The stick pusher would be ineffective and would probably aggravate the stabilizer stall.
Engine torque would probably make the aircraft roll left.
An airfoil [in this case the horizontal stabilizer] can be stalled in either direction. [think inverted spin entry]
When the flaps are deployed the aircraft will seek it's trim speed and wants to pitch up.
The horizontal stabilizer would than have to generate an upward component of lift to push the nose down.
Even though an increase in airspeed would increase stabilizer authority it would also increase the pitch up tendency the stabilizer had to counteract.
When the stabilizer stalled the aircraft nose pitched upward. The main wing would than stall.
The stick pusher would be ineffective and would probably aggravate the stabilizer stall.
Engine torque would probably make the aircraft roll left.
Last edited by Jetstream 823JS; 02-16-2009 at 08:24 PM.
02-16-2009, 06:51 PM
#113
Gets Weekends Off
Joined APC: Nov 2008
Position: Livin' the dream
Posts: 626
"If the system is operated before ice starts to build up, there is a danger that, when buildup begins, the pulsed inflations of the boot will cause a gap to form between the ice buildup and the deflated boot, so when it re-inflates it has little effect on the ice that can quickly wrap around the entire leading edge to points beyond the boot itself."
Premature ejaculation!!
As the NASA guys point out, modern boot operation susceptibility to bridging, is nil.
Premature ejaculation!!
As the NASA guys point out, modern boot operation susceptibility to bridging, is nil.
I'd hope not- to dissect the available data is tempting, especially to avoid similar problems, but what do we really know so far?
Not to put too fine a point on it though, but is anyone on this thread already ruling out bridging? I'd doubt that this NTSB investigation has ruled out bridging in this accident based on NASA's tests only, as NASA as far as I know has not tested the Q-400 specifically. Keep an open mind here, okay?
The only known facts we actually know right now are not conclusive in themselves.
02-16-2009, 06:53 PM
#114
Gets Weekends Off
Joined APC: Aug 2008
Position: Moving backwards
Posts: 220
Icywings if you do not realize how much you are embarrassing yourself, I am sorry. Please stop trying to fish in these forums.
I have about 2,000 hrs in the Q400. By no means even close enough to be an expert or even an authority on the airplane. But I thought I would add some insight from my limited experience with the airplane.
The airplane is a good icing airplane. I have about 2,000 hrs of 135 time in different types of planes flying around the Northwest (a lot of it during the icy winters). Some of those planes were good in the ice and some were not. The Q400 is the first airplane I feel comfortable flying over the North Cascades with a front passing through. That being said, I have never viewed de-ice/anti-ice systems as allowing me to loiter in icing conditions. They are only there to buy me time to get out of the ice. For this reason, I have never truly 'tested' what the Q400 airplane would be like with significant ice accumulation.
I have been thinking about adding some more specific details about the de-ice/anti-ice system. However, with the apparent fishing on this forum the little good judgment I have left has pushed me to not do so.
With some of the theories floating around I can see why the crew would react the way they did, from my limited experience with the airplane. However, it is still early in the investigation process and everything is still just theories.
As this thread goes forward and you go after the media for arm chair quarterbacking, please think if you are also trying to be a quarterback. I have had professional pilots try to dissect my actions with an icing incident I had with a Navajo about 4 years ago, and it kind of ****ed me off. I was very willing to learn from my mistakes and had a long discussion with my chief pilot about it. However, I kept hearing opinions from others how I should have dealt with it. They were not there to make the decisions in the heat of the moment. And the decisions I did make were what I thought would keep me alive, that I am still alive means at least a few of the decisions pointed me in the correct direction. By the way, I had launched into moderate ice, later had my boots fail and the icing went to severe at the airport I returned to.
When the investigation results come out it might say the crew was at fault. I hope it does not without casual factors attached and with no political influence. It might also say the crew was completely in the right, which I hope for. However, it could also be the results are somewhere in the middle. Whatever it is, the best thing we can do is learn lessons from this accident and not have a repeat; whether this comes about from a change in procedure, or an airplane redesign, or a new approach to ice systems.
I have about 2,000 hrs in the Q400. By no means even close enough to be an expert or even an authority on the airplane. But I thought I would add some insight from my limited experience with the airplane.
The airplane is a good icing airplane. I have about 2,000 hrs of 135 time in different types of planes flying around the Northwest (a lot of it during the icy winters). Some of those planes were good in the ice and some were not. The Q400 is the first airplane I feel comfortable flying over the North Cascades with a front passing through. That being said, I have never viewed de-ice/anti-ice systems as allowing me to loiter in icing conditions. They are only there to buy me time to get out of the ice. For this reason, I have never truly 'tested' what the Q400 airplane would be like with significant ice accumulation.
I have been thinking about adding some more specific details about the de-ice/anti-ice system. However, with the apparent fishing on this forum the little good judgment I have left has pushed me to not do so.
With some of the theories floating around I can see why the crew would react the way they did, from my limited experience with the airplane. However, it is still early in the investigation process and everything is still just theories.
As this thread goes forward and you go after the media for arm chair quarterbacking, please think if you are also trying to be a quarterback. I have had professional pilots try to dissect my actions with an icing incident I had with a Navajo about 4 years ago, and it kind of ****ed me off. I was very willing to learn from my mistakes and had a long discussion with my chief pilot about it. However, I kept hearing opinions from others how I should have dealt with it. They were not there to make the decisions in the heat of the moment. And the decisions I did make were what I thought would keep me alive, that I am still alive means at least a few of the decisions pointed me in the correct direction. By the way, I had launched into moderate ice, later had my boots fail and the icing went to severe at the airport I returned to.
When the investigation results come out it might say the crew was at fault. I hope it does not without casual factors attached and with no political influence. It might also say the crew was completely in the right, which I hope for. However, it could also be the results are somewhere in the middle. Whatever it is, the best thing we can do is learn lessons from this accident and not have a repeat; whether this comes about from a change in procedure, or an airplane redesign, or a new approach to ice systems.
Last edited by Splanky; 02-16-2009 at 07:04 PM.
02-16-2009, 07:00 PM
#115
Gets Weekends Off
Joined APC: Sep 2007
Position: Piloto
Posts: 172
Anyone who knows anything about tailplane icing and tailplane stalls knows the tail produces a tail down force, not an upward force. The center of lift is behind the center of gravity and the taildown force equalizes the nose down pitching moment of that causing positive dynamic stability.
NASA has a great video covering tail plane icing on, if I recall, a twotter. They made a mold of how the ice forms and attatched it to the horizontal stab. It took over 400 lbs of backpressure to recover from the tail stall. The recovery procedure is to pull back on the yoke to decrease the angle of attack on the stab and fly FAST with no flaps. Flaps deflects the airflow in a more downward direction aft of the wing which increases the angle of attack on the tail. If the flaps are extended on an airplane already close to a tail stall that could send it over the edge. When I saw the model of the airplane last moments the abrupt pitch seemed to occur when the A/P disconnect. If the tail was icing up and slowly losing lift the trim may have been winding up and when it disconnect the airplane seemed to pitch up then stall the wing and pitch down afterwards. The first rule of accident investigation is to not speculate but it makes for good conversation here. I remember watching a video of a Bonanza pilot talking about his tailplane icing incident and he flew it at a very high airspeed with no flaps all the way to the runway after recovering from a tail stall with enormous sticks forces.
Also keep in mind that the critical AoA the shaker and stall indicators look at are for a clean wing. The critical AoA of the wing will lower as ice forms therefore the snake, shaker, and pusher may not be totally accurate and may engage after part of the wing it stalling.
NASA has a great video covering tail plane icing on, if I recall, a twotter. They made a mold of how the ice forms and attatched it to the horizontal stab. It took over 400 lbs of backpressure to recover from the tail stall. The recovery procedure is to pull back on the yoke to decrease the angle of attack on the stab and fly FAST with no flaps. Flaps deflects the airflow in a more downward direction aft of the wing which increases the angle of attack on the tail. If the flaps are extended on an airplane already close to a tail stall that could send it over the edge. When I saw the model of the airplane last moments the abrupt pitch seemed to occur when the A/P disconnect. If the tail was icing up and slowly losing lift the trim may have been winding up and when it disconnect the airplane seemed to pitch up then stall the wing and pitch down afterwards. The first rule of accident investigation is to not speculate but it makes for good conversation here. I remember watching a video of a Bonanza pilot talking about his tailplane icing incident and he flew it at a very high airspeed with no flaps all the way to the runway after recovering from a tail stall with enormous sticks forces.
Also keep in mind that the critical AoA the shaker and stall indicators look at are for a clean wing. The critical AoA of the wing will lower as ice forms therefore the snake, shaker, and pusher may not be totally accurate and may engage after part of the wing it stalling.
02-16-2009, 07:02 PM
#116
On Reserve
Joined APC: Feb 2007
Posts: 17
I don't know if anyone has posted or seen this video yet but it's good information for any pilot.
Tailplane Icing
Tailplane Icing
02-16-2009, 07:03 PM
#117
Gets Weekends Off
Joined APC: Jun 2007
Position: Legacy FO
Posts: 4,105
We also must regonize that these intruders may not be journalists (assuming you would want to compliment the modern news media by calling them journalists). They may be lawyers looking for information or possibly family members or friends.
02-16-2009, 07:04 PM
#118
Banned
Joined APC: May 2007
Posts: 152
02-16-2009, 07:14 PM
#119
Gets Weekends Off
Joined APC: Nov 2008
Position: Livin' the dream
Posts: 626
I don't wanna sound like a jerk (although I'm good at it) but I guess thats kind of what is ****ing me off about this accidents coverage. Nowadays we've got so much info (or little, depending on how you look at it) that it is easy for many, especially the media, to "solve" what has happened in an aviation accident before an official investigation involving lots of time and expertise has been allowed to run it's course.
Go look at the thread about this accident on PPRuNe, I can almost guarantee you there's a ton of media types fishing for sensational junk to put in their stories. Ugh.
I guess I'm heartened by some things though. The internet is a great way to find info about things that concern us, and to bounce ideas off of each other.
Stay Safe out there
Respectfully,
Go look at the thread about this accident on PPRuNe, I can almost guarantee you there's a ton of media types fishing for sensational junk to put in their stories. Ugh.
I guess I'm heartened by some things though. The internet is a great way to find info about things that concern us, and to bounce ideas off of each other.
Stay Safe out there
Respectfully,
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