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