Challenger Crashe at TEB

Peter R. wrote:

Matt Whiting wrote:


Why? It is acceptable to "polish the frost smooth" per FAR 91.527.


Three words: New paint job


Won't hurt it if the rag is soft and you don't polish the frost clean
through to the paint. Keep in mind that you don't have to remove the
frost, just knock off the roughness. This doesn't take much effort
typically.


Matt

Ron McKinnon wrote:

"Matt Whiting" wrote in message

Peter R. wrote:

...
If deicing were not an option, I would have had to get a hotel and wait
until the frost melted off the next day, or some liquid deicing were
available. In no case would I have attempted to take off with it on the
wing surface.

Why? It is acceptable to "polish the frost smooth" per FAR 91.527.


Interesting. It seems a rather dubious practice to me. It would indeed
appear to be legal in the US - but, FWIW, it isn't legal in Canada.

Why? Smooth frost is less of an aerodynamic issue that a thick layer of
dirt, bugs and dust...


Matt

"Matt Whiting" wrote in message
...
Ron McKinnon wrote:

"Matt Whiting" wrote in message

Peter R. wrote:

...
If deicing were not an option, I would have had to get a hotel and wait
until the frost melted off the next day, or some liquid deicing were
available. In no case would I have attempted to take off with it on the
wing surface.

Why? It is acceptable to "polish the frost smooth" per FAR 91.527.


Interesting. It seems a rather dubious practice to me. It would indeed
appear to be legal in the US - but, FWIW, it isn't legal in Canada.

Why? Smooth frost is less of an aerodynamic issue that a thick layer of
dirt, bugs and dust...


Matt

The last two FAA seminars I have attended indicated
it was no longer considered good practice to fly with
ANY frost, polished or not.

Bob Barker N8749S

From: "Matt Whiting"
Ron McKinnon wrote:

"Matt Whiting" wrote in message
...Why? It is acceptable to "polish the frost smooth" per FAR 91.527.

Interesting. It seems a rather dubious practice to me. It would indeed
appear to be legal in the US - but, FWIW, it isn't legal in Canada.

Why? Smooth frost is less of an aerodynamic issue that a thick layer of
dirt, bugs and dust...

Be that as it may, arguing that its not as bad as something else (that you
shouldn't fly with either), isn't any argument at all for the acceptability
of flying with smooth frost.

Frost, smooth or otherwise, or other contaminants arguably affect the
aerodynamic behaviour. How much does it change with a given
level of contamination?, what level of contamination is significant?
or how significant is such a change? how much is too much? how
smooth is smooth enough? in what way will such change affect the
aerodynamic behaviour of the plane? (does it change the critical
angle of attack for the wings? the control surfaces?, what are
the new critical angles (what's the new stall behaviour? is a
tailplane stall more likely? will it spin easier? how does it change
rudder effectiveness?) for instance) are critical questions. But
these are not questions that a typical pilot is in a position to answer
operationally. This a job for computer simulations, and lab analysis
in controlled test conditions, and for test pilots in controlled test
situations.

Critical surfaces should be clean.

Ron McKinnon wrote:
From: "Matt Whiting"

Ron McKinnon wrote:


"Matt Whiting" wrote in message

...Why? It is acceptable to "polish the frost smooth" per FAR 91.527.

Interesting. It seems a rather dubious practice to me. It would indeed
appear to be legal in the US - but, FWIW, it isn't legal in Canada.

Why? Smooth frost is less of an aerodynamic issue that a thick layer of
dirt, bugs and dust...


Be that as it may, arguing that its not as bad as something else (that you
shouldn't fly with either), isn't any argument at all for the acceptability
of flying with smooth frost.

Frost, smooth or otherwise, or other contaminants arguably affect the
aerodynamic behaviour. How much does it change with a given
level of contamination?, what level of contamination is significant?
or how significant is such a change? how much is too much? how
smooth is smooth enough? in what way will such change affect the
aerodynamic behaviour of the plane? (does it change the critical
angle of attack for the wings? the control surfaces?, what are
the new critical angles (what's the new stall behaviour? is a
tailplane stall more likely? will it spin easier? how does it change
rudder effectiveness?) for instance) are critical questions. But
these are not questions that a typical pilot is in a position to answer
operationally. This a job for computer simulations, and lab analysis
in controlled test conditions, and for test pilots in controlled test
situations.

They only affect the aerodynamic behavior if they significantly affectt
he flow in the boundary layer. On some airfoils this a concern with
fairly small disturbances, but on others it isn't much of a concern at
all. Saying that you should not fly an airplane that has any frost on
it is just as silly as saying you should never take off with less than
full fuel. You have to know your airplane, nobody is arguing that.
Most light airplanes will fly just fine with polished frost on the wings
and even the control surfaces, I know my 182 did.


Critical surfaces should be clean.

Only if being clean is critical. :-) It often isn't.

Do you really wipe your entire airplane completely clean of bugs and
dirt after every flight? If you fly through bugs do you land
immediately to clean them off?


Matt

From: "Matt Whiting"
Sent: Friday, February 04, 2005 1:57 PM


Ron McKinnon wrote:
From: "Matt Whiting"

Ron McKinnon wrote:


"Matt Whiting" wrote in message

...Why? It is acceptable to "polish the frost smooth" per FAR 91.527.

Interesting. It seems a rather dubious practice to me. It would indeed
appear to be legal in the US - but, FWIW, it isn't legal in Canada.

Why? Smooth frost is less of an aerodynamic issue that a thick layer of
dirt, bugs and dust...


Be that as it may, arguing that its not as bad as something else (that
you
shouldn't fly with either), isn't any argument at all for the
acceptability
of flying with smooth frost.

Frost, smooth or otherwise, or other contaminants arguably affect the
aerodynamic behaviour. How much does it change with a given
level of contamination?, what level of contamination is significant?
or how significant is such a change? how much is too much? how
smooth is smooth enough? in what way will such change affect the
aerodynamic behaviour of the plane? (does it change the critical
angle of attack for the wings? the control surfaces?, what are
the new critical angles (what's the new stall behaviour? is a
tailplane stall more likely? will it spin easier? how does it change
rudder effectiveness?) for instance) are critical questions. But
these are not questions that a typical pilot is in a position to answer
operationally. This a job for computer simulations, and lab analysis
in controlled test conditions, and for test pilots in controlled test
situations.

They only affect the aerodynamic behavior if they significantly affectt he
flow in the boundary layer. On some airfoils this a concern with fairly
small disturbances, but on others it isn't much of a concern at all.
Saying that you should not fly an airplane that has any frost on it is
just as silly as saying you should never take off with less than full
fuel. You have to know your airplane, nobody is arguing that. Most light
airplanes will fly just fine with polished frost on the wings and even the
control surfaces, I know my 182 did.

The issue isn't whether it will fly at all, but what happens to its
flying characteristics, and whether you're still operating
with safe margins for error. A few anecdotal cases where it
'flew', does nothing to answer that. There are many other
cases on record where it didn't.

What, exactly is the expected level-flight stalling speed with
this particular amount of frost, 'polished' to this particalar
smoothness? Is it safe with the current loading, the current
density altitute, the current runway (the destination loading,
density altitude, and runway?) - do you have any safety
margin left? or have you used it all up by leaving frost on
the wings? or have you, in these particular circumstances
not affected it at all? What's the new stalling characteristics
of the stablizers, elevator and rudder effectiveness. Are you
going to be in the neigborhood of a tailplane stall on takeoff?
Is the frost layer uniform - does it affect the whole wing in the
same way?

You don't know. .

And its not just about 'knowing your airplane'. How many
pilots can say with assurance how much contamination
will significantly affect the flow in the boundary layer?, or for
which airfoils its a concern with fairly small disturbances?
There are no doubt some that can, I'll grant you. But this is
not the usual rule. (Off the top of your head - What is the
airfoil on your 182? How sensitive is it to contamination.
How much contamination is too much on your 182.
What thickness of frost is too much for this airfoil? How
'smooth' *does* it have to be? And then what about the
stabilizers, elevators and rudder? Exactly what is the new
level flight stalling speed?)

The proposition isn't that you shouldn't fly an airplane that
has *any* frost on it - it is that you shouldn't fly it with any
frost on the critical surfaces: wings, stabilizers, rudder
(propellers).

It is obviously 'legal' in the US (the original FAR citation
shows this), so in the US you may obviously feel free to
use your discretion in the matter. But that doesn't necessarily
mean it is safe.

In other places (Canada, for instance) it isn't even legal.

It doesn't appear that ice was a factor:


http://www.latimes.com/news/nationwo...ck=1&cset=true

The pilot is claiming that something broke:

http://www.wkyt.com/Global/story.asp?S=2902222

A radio report I heard said that the pilot said that he couldn't pull the
yoke back, at which point he discontinued the takeoff.

Of course, all this is almost irrelevant. The ground-huggers are out in
force now, exploiting this accident:

http://www.nj.com/news/ledger/index....0326181070.xml
http://www.nj.com/news/ledger/index....1476833170.xml


"I intend to use this accident to help persuade the FAA
(Federal Aviation Administration) that Teterboro Airport
has reached its capacity and that any additional flights
coming into this region should go through JFK or Newark
airports," said Rep. Steve Rothman (D-9th Dist.).

Of course, he doesn't represent the people around those airports, nor those
that would be impacted by the increased delays. Well, actually, some
people in his district would be impacted, but he'd just find someone else
to blame.

Teterboro Airport was there long before any of these businesses or
residents.

- Andrew

Gary Mishler wrote:

"Capt.Doug"
There was no visible moisture. The sky was crystal clear. The only wing
contamination possible would have been light frost on the bottom of the
wing
where the fuel had cold-soaked after landing- if the plane had made a
quick-turn. No other aircraft had requested de-icing. I doubt that the
cause
was wing ice.

Frost on top of the wings, and more importantly - on top of the T-tail is
highly likely. I have flown a T tail jet for 25 years and you can get frost
on top of the wings and tail very easily in the early morning with the right
conditions.

An AP article stated that the temperature at the time was 20 degrees. I think
that rules out frost, but I'm not sure. Another report today stated that there
was no indication that ice was a factor.

George Patterson
He who would distinguish what is true from what is false must have an
adequate understanding of truth and falsehood.

Ron McKinnon wrote:

From: "Matt Whiting"
Sent: Friday, February 04, 2005 1:57 PM

They only affect the aerodynamic behavior if they significantly affectt he
flow in the boundary layer. On some airfoils this a concern with fairly
small disturbances, but on others it isn't much of a concern at all.
Saying that you should not fly an airplane that has any frost on it is
just as silly as saying you should never take off with less than full
fuel. You have to know your airplane, nobody is arguing that. Most light
airplanes will fly just fine with polished frost on the wings and even the
control surfaces, I know my 182 did.


The issue isn't whether it will fly at all, but what happens to its
flying characteristics, and whether you're still operating
with safe margins for error. A few anecdotal cases where it
'flew', does nothing to answer that. There are many other
cases on record where it didn't.

My 182 flew just fine. I'm not aware of any 182 accidents from polished
frost and I know many people with many thousands of hours operating 182s
in my area and climate.


What, exactly is the expected level-flight stalling speed with
this particular amount of frost, 'polished' to this particalar
smoothness? Is it safe with the current loading, the current
density altitute, the current runway (the destination loading,
density altitude, and runway?) - do you have any safety
margin left? or have you used it all up by leaving frost on
the wings? or have you, in these particular circumstances
not affected it at all? What's the new stalling characteristics
of the stablizers, elevator and rudder effectiveness. Are you
going to be in the neigborhood of a tailplane stall on takeoff?
Is the frost layer uniform - does it affect the whole wing in the
same way?

You don't know. .

Same way you don't know after you fly through a swarm of bugs. Does
this freak you out also? It never bothered me. I can detect a stall
pretty easily in all of the airplanes I've flown. If the stall
commences at 60 knots instead of 50 knots, I don't really care, I just
stay above that airspeed.


And its not just about 'knowing your airplane'. How many
pilots can say with assurance how much contamination
will significantly affect the flow in the boundary layer?, or for
which airfoils its a concern with fairly small disturbances?
There are no doubt some that can, I'll grant you. But this is
not the usual rule. (Off the top of your head - What is the
airfoil on your 182? How sensitive is it to contamination.
How much contamination is too much on your 182.
What thickness of frost is too much for this airfoil? How
'smooth' *does* it have to be? And then what about the
stabilizers, elevators and rudder? Exactly what is the new
level flight stalling speed?)

I don't care exactly what it is as I mentioned above. The stall speed
varies constantly with loading and many other factors. If you fly based
on what the ASI tells you and not what the airplane is telling you, then
you are going to be a statistic some day.


The proposition isn't that you shouldn't fly an airplane that
has *any* frost on it - it is that you shouldn't fly it with any
frost on the critical surfaces: wings, stabilizers, rudder
(propellers).

And I disagree with that proposition and have done so successfully for
27 years. It just requires a little common sense and discussion with
people who have a lot of experience in your make and model.


It is obviously 'legal' in the US (the original FAR citation
shows this), so in the US you may obviously feel free to
use your discretion in the matter. But that doesn't necessarily
mean it is safe.

It is legal and safe if done properly. Just like most other aspects of
aviation. However, I'm not suggesting you should do it. I'm just
saying that for many of us it isn't a big deal.


In other places (Canada, for instance) it isn't even legal.

Then you shouldn't do it in Canada.


Matt

Andrew Gideon wrote:

It doesn't appear that ice was a factor:


http://www.latimes.com/news/nationwo...ck=1&cset=true

The pilot is claiming that something broke:

http://www.wkyt.com/Global/story.asp?S=2902222

A radio report I heard said that the pilot said that he couldn't pull the
yoke back, at which point he discontinued the takeoff.

Probably all that frost on the elevator made it too heavy to lift up for
rotation. :-)

It does sound like something failed that blocked or froze the control
column. Sounds unlikely, but this was an experienced captain (one
source said 15,000 hours) so I trust he knew that the stick wasn't
moving enough for takeoff.

Matt