Author Topic: Continental (Colgan)-3407 -8 Crash in Buffalo  (Read 307292 times)

Offline frantzy

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #125 on: February 14, 2009, 12:26:16 PM »
As the flaps extend the airflow aft of the wings creates a greater downwash(angle of attack) on the horizontal tail that may stall if the tail surface is contaminated with ice.

I have a hard time envisioning  how the disturbed air from lowered flaps would affect the horizontal stab of this particular aircraft, given how much higher the horizontal stab is above the main wings.  I am not an engineer so clearly I must be missing something but it seems to me that the horizontal stab is well above the downwash of the main wings, flaps or no flaps.  Explanations welcome.



I wouldn't think it would be downwash, but extending flaps would change the pitch of the plane, and thus the angle of attack for the horizontal stabilizer.    Deformed with ice, it might be barely creating lift in a clean configuration, and then lose all its lift in the dirty configuration.

Offline GuessWho08

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #126 on: February 14, 2009, 12:28:24 PM »
As the flaps extend the airflow aft of the wings creates a greater downwash(angle of attack) on the horizontal tail that may stall if the tail surface is contaminated with ice.

I have a hard time envisioning  how the disturbed air from lowered flaps would affect the horizontal stab of this particular aircraft, given how much higher the horizontal stab is above the main wings.  I am not an engineer so clearly I must be missing something but it seems to me that the horizontal stab is well above the downwash of the main wings, flaps or no flaps.  Explanations welcome.




in any effect, it would at the very least increase the Angle of attack on the tail. If there is already Icing, this could increase the chance of a Tail Stall.

Offline iskyfly

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #127 on: February 14, 2009, 12:42:35 PM »

http://www.airdisaster.info/forums/viewtopic.php?f=6&t=2054&st=0&sk=t&sd=a&start=25#p26656

Quote
According to the NTSB briefing, shortly after flap movement, the plane experienced large and rapid pitch excursions.....onset of pitch instabilty in conjunction with flap movement is a classic tail stall symptom.

Offline KSYR-pjr

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #128 on: February 14, 2009, 12:48:41 PM »
I wouldn't think it would be downwash, but extending flaps would change the pitch of the plane, and thus the angle of attack for the horizontal stabilizer.    Deformed with ice, it might be barely creating lift in a clean configuration, and then lose all its lift in the dirty configuration.

Ah, makes sense now. 

Offline iskyfly

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Offline joeyb747

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #130 on: February 14, 2009, 02:21:15 PM »
Hello everyone. I am an aircraft mx. Turbo-props are more suseptable to icing, as they only use pneumatic boots insted of heated bleed air. The engine inlets are very prone to ice as they are much smaller then a jet engine intake.  It is a sad situation. I wonder if the crew knew about the ice, and if there anti-ice system was activated. Other airplanes made the airport, why not Colgan? Mt guess is a combo of Icing and Crew Error. Ice on the wings will make an airplane, particularly a high wing like the dash 8, or ATR 42 or 72, or a Fokker series, rapidly become uncontrolable. Ive listened to the audio several times and no indication of mechanical issue is evident. What ever it was happened fast, there was no stress in the co-pilots voice as she worked the radio.

Offline iflyhi

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #131 on: February 14, 2009, 02:35:01 PM »
a prior poster alluded to   carb  icing.     please enlighten me.  what kind of carburators are used on a jet engine ?    HUH?

Offline joeyb747

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #132 on: February 14, 2009, 03:12:16 PM »
Its not "Carb Ice" in a turbo prop. You get carb ice in a light single or light twin. Its similar. Ice or water vapor gets inside the powerplant and shuts the engine down, basically puts out the fire. Aircraft are equipped with two ignition systems. ground ignition, witch is used for starting, and flight ignition, witch is used in flight in rain, snow, sleet, or any "wet air" condition. After starting, the ignition system is usually in the "OFF" position. The flight ignition system acts like a sparkplug in your car and keeps re-lighting the fire. If the air is dry, the engine will continue to burn without additional spark. If you listen to any jet fuel powered aircraft star you will hear the compressor spin up and once the fuel valve opens you will hear a seried of "clicks". Thats the ignition system firing. Once the fuel lights, you will hear a "wosh" sound as the engine spools up. When the flight ignition system is activated, the "clicking" will continue until the system is turned off. The flight ignition system will also attempt to re-start the engine if a flame-out occurs. I hope that answers your question.   

Offline joeyb747

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #133 on: February 14, 2009, 03:16:16 PM »
Turbo prop or jet engines dont have a "carb" per say. mostly its your lighter airplanes. Cessna 180s', Pipers, Mooneys, and light twins, such as a Baron, or a Navajo have a carb very similar to one on you typical classic car.

Offline LeoBern

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #134 on: February 14, 2009, 04:31:23 PM »
Just listening to the NTSB briefing. A couple of interesting things that may throw a little doubt into the tailstall theory (apologies for speculation but it seems we're all doing it to some extent).
1) Appears as though the de-ice [boot-system inlcuding tail] was on auto and properly working--no indication though as to when it was turned on.
2) The orientation of the A/C revealed a couple of intereting things a) pointing AWAY from runway B) reasonably flat [i.e. not nose first].
3) Flaps did not make it down to 15, made it as far as 10. <--this actually may support tailstall though since any change of aa can amplfy tail iciing.

Maybe some of us where too quick (myself included to jump on the tailstall being the only culprit).
Looks like we'll find out more as the analysis continues.

Thanks for all the good comments and learned responses. My heart goes out to the crew and passengers. 

         

Offline sdorshan

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #135 on: February 14, 2009, 05:26:35 PM »
What an awful tragedy. It almost seems disrespectful discussing the causes of this crash while families are grieving. If any of you are reading this, my condolences.

The reason we do discuss the causes of any crash so dispassionately is to prevent the same thing from happening again. These same planes are flying through these same conditions every day.

What I haven't seen mentioned as a contributing factore is the location of the CG. While having a CG too far rearward is a known cause of accidents, if the tail loses effectiveness, having the CG too far forward could make the difference between recovery and disaster. Remember that the tail pushes down and keeps the nose from flipping forward.

What is very important to find out is what the current safety margin is in aircraft flying through ice. Are airplanes flying right on the verge of crashing, or are they well within the margin of safety for the conditions they are in?

If an airplane is lightly loaded and collecting ice, should the crew move the passengers rearward? I think that CG location will be found to play a part in such crashes.

Scott

Offline KSYR-pjr

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #136 on: February 14, 2009, 05:58:45 PM »
2) The orientation of the A/C revealed a couple of intereting things a) pointing AWAY from runway B) reasonably flat [i.e. not nose first].

I attributed this to a stall and partial recovery.  If indeed the eyewitness reports are true (and we all know how inaccurate they tend to be), then most likely an aircraft that rolled, lost a thousand feet, and partially recovered could very easily be on another, even opposite heading.

Offline napper505

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #137 on: February 14, 2009, 06:42:40 PM »
Hey

I looked at the video and then at google earth. A/C 4200  (3407)appeared to come down facing perpindicular to the runway that it was approaching.

It came down with flight controls intact. In the videos/images I can see the Inboard flaps.  Outboard flaps are visible on the ground beside the burned our hull. MLG, tires intact are prominent in one image.

Initial vertical fire was in fact port side wing burning raised in the air.

you can see the orientation by looking at this video

http://watch.ctv.ca/news/latest/chopper-footage/#clip139735

Compare this to the original video and notice the elevators in the climb position. As Hydraulic fluid is lost the Elevators have gone to neutral. in previous vid.

http://www.cnn.com/2009/US/02/14/plane.crash.newyork/index.html#cnnSTCVideo

Is that ice I see on the boot?  No it is damage . The bullet fairing where H-stab and v-stab meet is damaged as well.

Looks like she rolled pitched, applied power and didn't make it.. (controller left her too long at 4000 ft asl)

It is a very powerful A/C hard to believe.  4500 Hp. per engine.

Napper505







Offline iskyfly

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #138 on: February 14, 2009, 07:10:56 PM »
(controller left her too long at 4000 ft asl)
huh? ultimately the PIC determines course / altitude if in a dangerours situation. not the controller.

Offline iskyfly

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #139 on: February 14, 2009, 07:12:20 PM »
NTSB says that all "4 corners" of the plane were found in a matter indicating that the plane impacted the ground flat. not a nose dive.

Offline joeyb747

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #140 on: February 14, 2009, 08:13:26 PM »
Here is the full story from my service provider. The most isteresting part to me is in the first line. The airplane was pointed away from the airport.

CLARENCE, N.Y. — A commuter plane that smashed into a house was pointed away from the airport it was trying to reach, investigators said Saturday, noting that it apparently fell flat.

Flight data showed the plane's safety systems warned the pilot that the aircraft was perilously close to losing lift and plummeting from the sky. The ensuing crash killed 49 people on the plane and one in the house.

Continental Connection Flight 3407 didn't nose-dive into the house, as initially reported by some witnesses, said Steve Chealander, a National Transportation Safety Board member.

The Newark, N.J.,-to-Buffalo flight was cleared to land on a runway pointing to the southwest, but it crashed with its nose pointed northeast, Chealander said. It will take as many as four days to remove human remains from the site, which he called an "excavation."

"Keep in mind, there's an airplane that fell on top of a house, and they're now intermingled," he said.

The plane — on its descent to Buffalo Niagara International Airport in a light snow and mist — plunged suddenly about six miles shy of the runway and exploded.

A "stick shaker" and "stick pusher" mechanism had activated to warn Capt. Marvin Renslow that the plane was about to lose aerodynamic lift, a condition called a stall that means there's not enough air under the wings to keep the plane elevated.

When the "stick pusher" engaged, it would have pointed the nose of the plane toward the ground to try to keep air under the wings, the last moments before it stalled and plunged to the ground.

Crash investigators picked through incinerated wreckage Saturday, gathering evidence to determine what brought down the plane. Icing on the aircraft is suspected to have played a role, but officials have stopped short of calling that the cause.

Experts were analyzing data from the black boxes, including statements by crew members about a buildup of ice on the wings and windshield of the plane, Chealander said.

Other aircraft in the area Thursday night told air traffic controllers they also experienced icing around the time that the plane went down.

Icing is one of several elements being examined by investigators, Chealander said, adding that a full report will probably take a year.

DNA and dental records will be used to identify the bodies, he said.

One aspect of the investigation will focus on the crew, how they were trained and whether they had enough time to rest between flights. Other investigators focused on the weather, the mechanics of the plane and whether the engine, wings and various mechanics of the plane operated as they were designed to.

Initial visual inspection of the engines indicates they were working properly, Chealander said.

Offline napper505

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #141 on: February 14, 2009, 08:57:24 PM »
Hey..

 
3407 X'd  out and then  and only then did the controller ask about icing.

wouldn't it be prudent to to declare "icing conditions" on any approach or any Departure.

Not blaming the Controller!!..  Not 1  a/c even mentioned it to the controller until after the incident.

between Altitude 500 and say 230 asl.  I am pretty sure most modern A/C have weather radar.

So Whats the problem if your flying on Auto..  Was there someone in the jump seat distracting them?


Napper505




Offline paldriver

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #142 on: February 14, 2009, 09:11:34 PM »
Here's the Flightaware log showing decent of ~1000 ft/min after 9:58pm

http://flightaware.com/live/flight/CJC3407/history/20090213/0220Z/KEWR/KBUF/tracklog
is that unusual?

Not even close.  I routinely descend in my Bonanza at 1,000 fpm when there are no passengers on board (non-pressurized aircraft tends to blow out eardrums of passengers at rates greater than 600fpm).   Pressurized airline transport aircraft will routinely descend between 2,000 and 4,000 fpm, depending on ATC's instructions.

Never in turbo-props more than 1500-2000ft unless necessary..4000fpm is not safe or necessary. Norm in Dash8 pax service would be +/- 1000 to 1500 for enroute descents
« Last Edit: February 14, 2009, 09:13:13 PM by paldriver »

Offline paldriver

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #143 on: February 14, 2009, 09:16:06 PM »
If there are any dash-8 drivers out there here are a couple of questions regarding your ils profile.  When do you start confirguring? Does the tail have boots aswell? I ask because if there was alot of ice on the tail once you start putting out flaps you can stall the tail which can lead to a departure from pitch control. Usually causes an abrupt pitch down movement. The recovery is to return to the last config before the stall occurred, apply max power and pull the nose up.

My prayers go out to crew and passengers of 3407. God Speed.

There are Elevator Boots, flaps usually go to first setting while on LoC, below GS. Gear and ldg flaps are extended when GS indicator is 1 dot above, so when the autopilot or pilot flying begins flying the GS in the descent...the airplane is configured for smooth appch. Every company can set thier own SOP's,
but all would be similar.  I in my experience...with all de-ice equipment on/or off...have never encountered a tail stall. The icing reported is really no cause for concern, but it all depends on how a crew decides to handle it or how well the equipment is working. As always, there is no such thing as a little iCE!
« Last Edit: February 14, 2009, 09:21:07 PM by paldriver »

Offline KSYR-pjr

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #144 on: February 15, 2009, 11:34:52 AM »
Never in turbo-props more than 1500-2000ft unless necessary..4000fpm is not safe or necessary. Norm in Dash8 pax service would be +/- 1000 to 1500 for enroute descents

I was considering jet transport aircraft in that as well.   In NY airspace I overheard ATC ask a pilot of a regional jet what rate at which he was descending, and after replying the pilot offered up 3,500 fpm to expedite the descent.   

Offline Jason

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #145 on: February 15, 2009, 01:33:23 PM »
I was considering jet transport aircraft in that as well.   In NY airspace I overheard ATC ask a pilot of a regional jet what rate at which he was descending, and after replying the pilot offered up 3,500 fpm to expedite the descent.

If we're light (and don't have pax), we can do as great as 6,000 fpm on a cold day in the CJ3.  On live legs, any more than 3,000 or 3,500 fpm is uncomfortable for most pax in the back.
« Last Edit: February 15, 2009, 01:34:59 PM by Jason »

Offline KSYR-pjr

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #146 on: February 15, 2009, 01:35:55 PM »
On live legs, any more than 3,000 or 3,500 fpm is uncomfortable for most pax in the back.

In what way, Jason?  I thought the pressurized cabin neutralized the pressure differences caused by dropping that fast?

Offline cessna157

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #147 on: February 15, 2009, 01:54:34 PM »
In the -700s I flew, idle descent with the brakes out would usually give a descent rate between 3500-4500 fpm above 10000, and about 2000-2500 below 10000.  The -900 would usually be a little less since it is much heavier and sleaner aircraft (very hard to slow down).  It's not very fun for the passengers though, as the pitch angle is so low (sometimes would be almost 15 degrees nose down).  Remember, don't spill the folks' drinks!

Offline Jason

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #148 on: February 15, 2009, 02:10:33 PM »
In what way, Jason?  I thought the pressurized cabin neutralized the pressure differences caused by dropping that fast?

That high a rate of climb or descent is uncomfortable in the sense that the pitch angle is rather pronounced, not necessarily having to do with the pressurization system.

Offline Tripp

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Re: Continental (Colgan)-3407 -8 Crash in Buffalo
« Reply #149 on: February 15, 2009, 03:40:07 PM »
>Latest on the Colgan crash is that they were on autopilot when control was lost.<
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OK, so we may have more to think about than just a tail stall.  This was posted on another forum by a very experienced airline pilot that I know:

They also have said the stall warning/stick shaker sounded.  This should have kicked the A/P off.  Some inconsistencies here I think.  I think that it is sounding more and more like less of a weather event and more of a pilot issue.  I bet they leveled off and never added power, and stalled, and that the very inexperienced FO was flying, and the Capt. was dealing with other issues, and lost track of what was happening until it was too late.  That’s my speculation as of right now, as I have seen this happen many times to much less of a catastrophic end.  Sad.