Wing De-Icing Question

On Feb 15, 11:59*am, Gezellig wrote:
On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

On Feb 15, 4:23*pm, Dudley Henriques wrote:
On Feb 15, 11:59*am, Gezellig wrote:



On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

Maybe a silly notion/question buuuut...if this (pitching/roll -this
from new reports as of 2/16) had occurred at a higher altitude, 7000
ft say, would the plane have entered a 'flat' spin? Was the impact
indicative of such?

wrote in message
...
On Feb 15, 4:23 pm, Dudley Henriques wrote:

Cool! Let's speculate on speculation.

On Feb 16, 8:01*am, wrote:
On Feb 15, 4:23*pm, Dudley Henriques wrote:



On Feb 15, 11:59*am, Gezellig wrote:

On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

Maybe a silly notion/question buuuut...if this (pitching/roll -this
from new reports as of 2/16) had occurred at a higher altitude, 7000
ft say, would the plane have entered a 'flat' spin? *Was the impact
indicative of such?

Difficult to say. I'm far from being the expert on transport aircraft.
My understanding is that if, and that is still a big IF, tailplane
icing was involved in the Buffalo accident, it was the lowering of the
flaps and the cfg change to the wing increasing the aoa on the tail
that was the factor actually taking them into stall. If that was the
cause, the actual breaking of the stall caused by the ice on various
leading edges could very well have taken them into uncontrolled auto
rotation. For that to happen, yaw had to be present at the stall.
The scenario above assumes low altitude due to the flap extension
factor.
At this stage in any accident investigation, it's always conjecture.
Already however, the seldom discussed issue of tailplane icing is
getting a lot of attention throughout the entire aviation community
and that alone is good for flight safety. The NTSB investigation will
provide the answer I'm sure.
Dudley Henriques

On Sun, 15 Feb 2009 14:23:43 -0800 (PST), Dudley Henriques wrote:

On Feb 15, 11:59*am, Gezellig wrote:
On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

Following the theory, for the sake of discussion, is this pilot error
and is it avoidable?

I realize they can't see the tail but icing on the windshield was
reported.

I have icing, weather, an aircraft with a history of tail icing (due to
its design)....even if they had no stick inputs, do you go to flaps
knowing that you could possibly cause a sever pitch down and the
inevitable results?

On Mon, 16 Feb 2009 11:18:45 -0500, Gezellig wrote:

On Sun, 15 Feb 2009 14:23:43 -0800 (PST), Dudley Henriques wrote:

On Feb 15, 11:59*am, Gezellig wrote:
On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44*pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: *On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

Following the theory, for the sake of discussion, is this pilot error
and is it avoidable?

I realize they can't see the tail but icing on the windshield was
reported.

I have icing, weather, an aircraft with a history of tail icing (due to
its design)....even if they had no stick inputs, do you go to flaps
knowing that you could possibly cause a sever pitch down and the
inevitable results?

NTSB: Flight 3407 Was On Autopilot Before Accident

Mon, 16 Feb '09
Practice Violated Company Policy For Icing Conditions

A National Transportation Safety Board official confirmed Sunday that
downed Continental Express flight 3407 was being flown on autopilot at
the time of the crash, contrary to normal procedures.

In conjuction with FAA recommendations, NTSB spokesman Steve Chealander
said Colgan Air, the plane's operator, recommends that pilots manually
fly during all conditions... and requires them to do so when there's
evidence of severe icing.

"You may be able in a manual mode to sense something sooner than the
autopilot can sense it," Chealander told the Associated Press,
emphasizing the need to hand-fly the airplane to better feel how it's
really flying when conditions are critical.

An autopilot will trim out an aircraft, within its capabilities, to
compensate for changing conditions -- including airflow disturbances
caused by icing -- without the flight crew necessarily becoming aware of
any abnormalities.

On Feb 16, 9:18*am, Gezellig wrote:
On Sun, 15 Feb 2009 14:23:43 -0800 (PST), Dudley Henriques wrote:
On Feb 15, 11:59 am, Gezellig wrote:
On Sun, 15 Feb 2009 06:00:13 -0800 (PST), Dudley Henriques wrote:
On Feb 13, 4:44 pm, "Robert11" wrote:
Hello,

I guess de-icing is going to be a popular subject.

Question, please: On commercial jet airliners like, e.g., a 767 or 757, is
there any in-flight deicing system for the wing and tail surfaces, other
than a leading edge pneumatic boot ?

What about the "main," large upper surfaces ?

How in general is wing de-icing accomplished on these new, modern jets ?

Thanks,
Bob

There's a very good chance the Boston crash might have been tailplane
icing.
DH

To explain the erratic flight behavior?

It's just a guess, but yes. I viewed a NASA film only this morning on
this issue. The key if correct would be that whatever happened
happened immediately after they went to 15 degrees of flaps. That
would have increased the aoa on the tail surface leading edge. That
leading edge is sharper than the wing leading edge and very
susceptible to icing. Assuming the boundary layer sep point was moving
aft on the stabilizer already, when they lowered the flaps they could
have easily exceeded the CLmax for the tail.
Even if this theory is correct, I'd be looking for additional factors
related to icing coupling to cause the autorotation they seemed to
have entered prior to impact.
It's all theory anyway. The NTSB will come up with something as they
progress with the investigation.
DH

Following the theory, for the sake of discussion, is this pilot error
and is it avoidable?

I realize they can't see the tail but icing on the windshield was
reported.

I have icing, weather, an aircraft with a history of tail icing (due to
its design)....even if they had no stick inputs, do you go to flaps
knowing that you could possibly cause a sever pitch down and the
inevitable results?

Now they're looking at the pilot's possibly having the
autopilot on during the descent into and during the icing conditions,
against company policy. Anyone who has flown an autopilot will know
that it isn't the smartest beast and can cause problems. See
http://www.google.com/hostednews/ap/...BGCYgD96CNPN81

Dan

This discussion is rapidly running in the wrong direction.
While I do not share the admonition of some that it is "taboo" to speculate
about causes of an airplane accident before all of the factual information is
in, it is certainly unhelpful and disrespectful to start crying "pilot error"
and lamenting all of the things they should or should not have done, before any
of the salient facts of the scenario are in place. Similarly, it is reckless to
start decrying insufficiencies in any of the aircraft's systems or their use
without a solid factual basis for these assumptions.

It may be useful to discuss airframe icing and tailplane icing, and it is
perhaps pertinent to speculate about its role in the current case, but to go
much further can only foster misunderstanding and misinformation. Have instead
some respect for the people who lost their lives, and for their families, as
well as for the flight crew who just may have known a thing or two about how to
fly their airplane. . .

On Feb 16, 7:51*pm, VOR-DME wrote:
This discussion is rapidly running in the wrong direction.
While I do not share the admonition of some that it is "taboo" to speculate
about causes of an airplane accident before all of the factual information is
in, it is certainly unhelpful and disrespectful to start crying "pilot error"
and lamenting all of the things they should or should not have done, before any
of the salient facts of the scenario are in place. Similarly, it is reckless to
start decrying insufficiencies in any of the aircraft's systems or their use
without a solid factual basis for these assumptions.

It may be useful to discuss airframe icing and tailplane icing, and it is
perhaps *pertinent to speculate about its role in the current case, but to go
much further can only foster misunderstanding and misinformation. Have instead
some respect for the people who lost their lives, and for their families, as
well as for the flight crew who just may have known a thing or two about how to
fly their airplane. . .

Keep in mind that this is a pilot's discussion group. Some of us fly
in conditions similar to that in existence for the Buffalo crash. As
with all such events, there are things to be learned. I subscribe to
"learn from your mistakes, but it's better to learn from the mistakes
of others because you won't live long enough to make all the mistakes
yourself."

As each new bit of information about this event comes available, I try
to imagine myself in the same situation and try to figure out what was
going on.

I had previously been shown the NASA video on tailplane icing while
attending a Flight Safety Inc recurrent training course for the
Citation. Previously, I'd never heard of this before. Hearing some
of the preliminary information about the Buffalo event reminded me of
this video so I found it on-line and watched it again and I'm glad I
did because I was remembering some of it incorrectly.

Anyway, more recent information is a bit inconsistent with the
"tailplane icing" theory, namely, that the flight data recorder says
that both the stick shaker and stick pusher were activated. This are
activated (at least in the Citation) by angle of attack sensors which
are electrically anti-iced. I can't see how this could happen in the
tailplane ice induced stall scenario.

The information about excessive bank angle would also be inconsistent
with this, except that if it really were tailplane stall due to ice,
the yoke might have been yanked forward and out of the hands of the
pilot. Attempting to pull it back might have resulted in inadvertent
aileron deflection, causing the roll.

K l e i n

VOR-DME wrote:
This discussion is rapidly running in the wrong direction.
certainly unhelpful ... disrespectful ... reckless ... foster
misunderstanding and misinformation

Yeah I don't really disagree, but egads, this is Usenet and for that
sake r.a.p. The epitome of inconsequential. Who cares what's said here?