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