My first freezing rain encounter

[[email protected]]

The weather was perfect for flying yesterday morning, sunny, mostly
blue sky with about 12000' ceiling and little wind (unlike the day
before when we canceled our flying plan due to 13G24 wind). As usual,
we checked weather sites, TAF/weather map etc before heading to the
airport. Bad weather is moving in but not until later in the day with
3000' ceiling at 3pm and light rain predicted at midnight or so. Our
plan was just to do some local IFR training flights taking turns
wearing foggles or acting as the safety pilot.
After entering the gate, we glanced at the ramp and saw quite a bit
of activities with several vehicles and a small group of people at the
north side of runway 24. In closer look, we saw a plane landed off the
runway in the grassy area with half of the wing stuck in a fence. We
immediately thought that the accident was due to the gusty/windy
condition the day before. It turned out that it was due to an engine
trouble on take off, luckily the pilot walked away unarm. We saw both
the pilot and the owner in the pilot lounge. Both looked quite grave
and were busy checking AIG insurance policy on open pilot cause.
We have always done a thoroughly preflight inspection and
preparation but this incident made us double-checks everything. After
plugging in the Reiff heaters and put on the nose mitten, Rick went and
chatted with a friend who was preheating his with a propane tank. He
also had a new engine and we both felt that preheating was needed even
in temp near 40F. The was quite a lot of activities on the ramp and in
the pattern in this relatively warm January weather. We went to the
mall nearby to pick up some tools at Sears while the engine being
heated. In checking the sky after our shopping, I was somewhat
concerned of the overcast instead of earlier blue sky but Rick assured
me that the ceiling should stay high enough for our practices.
We had planned to take off at before noon, but all the activities
added up and we did not depart until 1pm. The tanks were more than half
full. We thought of topping off but to save time, Rick suggested that
instead of flying northeast to Pawling VOR, he could do his practice on
the way north to Columbia. We could fuel there and I could fly to
Pawling on the swayback for my practice turn. ATIS at taxi time
indicated 5000' ceiling with about 2C spread between temp and dew
point.
While Rick was under the hood, I noticed that both the ceiling and
visibility seemed to get worse as we approached 1B1, so I suggested him
to cut the practice short and just prepared to land. Columbia AWOS
indicated wind at 200, 12 gusting to 18 (in contrast with 6 knots wind
at Dutchess) and with only 1C spread between temp and dew point. We
quickly fueled up, sumped the fuel, did a walk around inspection,
listened to AWOS then took off again. Ceiling had lowered to 3500' and
temp and dew point were both at 3C. I turned on the pitot heat and
made sure that cowl flap was close and the engine was leaned. After
about 15 to 20 minute under the hood, I heard Rick said in a somewhat
alarming voice "Change your plan, we are heading back to Dutchess - It
has started to rain". Then his raised his voice "Full throttle, full
throttle, we have ice on the windshield". Rick immediately put on the
defroster while I flipped on all our lights, landing/taxi/nav and
double checked that the pitot heat was on, cowl flap close, carb heat
off, engine leaned. We wanted the engine to kick off as much heat as
possible. At the same time, I was also trying to descend to a lower
altitude while keeping the speed just below the yellow arc. Rick wanted
me to go down to 2000' both for warmer air and less headwind (we have
something like 40' headwind at 3000') but I settled for 2500'thinking
altitude was my friend. Rick told me the GPS showed the nearest airport
was Kingston at 7nm and asked me whether I wanted to land there. Our
encounter with freezing rain was quite brief probably less than a
minute, because the windshield ice seemed to start melting where the
defroster hit at the pilot's side and there was no evidence of
additional ice build up. I had plenty of lift at full throttle, had to
pull back the power to stay at 2500' and not getting in the yellow arc.
I told Rick that I would continue south to Dutchess toward better
weather. KPOU ATIS indicated ceiling of 4000' with 1C spread between
temp and dew point. I contacted the tower for landing and also
reported our light icing encountered. The tower told us that they would
notify flight service. By this time, my side of the windshield was
clear enough for VFR. In my vague recollection, I probably relied
mostly on the instrument panel trying to keep straight and level,
descent at steady rate, following the VOR radial back to KPOU. I have
not officially started my instrument training but had done dozens of
foggles hours and had just spent the entire week playing with my
Christmas present, Elite v.8 with the IFR training manual. The
practices really came in handy.
In setting up for landing, I tried to stay high and slipped in with
only 10-degree flap. Over the fence, I was still pretty high and
somewhat fast so I dropped to 20-degree flap and reduced power to near
idle to make sure that I would not land long on the 3000 feet runway.
The landing was good and I was able to turn left to Alpha taxiway right
to our tie-down area.
The windshield was totally clear by the time we landed. I immediately
got out and check the wings. They were still coated with a clear thin
layer of ice which was melting quickly at 38F ground temperature.
After my icing report to the tower, there were two planes taking off
northbound. On our way out of the airport, we noticed several people
standing near the ramp area having their picture taken. Rick stopped
and asked whether they planned to go up soon. They nodded with big
smiles. The pilot was on the ramp getting the plane ready. Rick told
the passengers about the freezing rain/icing and suggested that should
not go up. I am not sure whether they comprehend the danger of the
situation by the look on their faces. I just hope that they would tell
the pilot of our advice.
In reviewing the incidence, we realized that we have made several
small errors. First, we should leave a wider margin of time for the
incoming bad weather. Secondly, we should not have changed our flight
plan at the last minute. If we had planned to go north to Columbia, we
would have paid closer attention to Albany TAF and weather report.
After our flight, I checked my mail and found an urgent winter storm
watch and warning for Albany region which remained in effect from noon
to 5pm:
"WARM MOIST AIR AHEAD OF A WARM FRONT MOVING INTO THE NORTHEAST FROM
THE OHIO VALLEY WILL RIDE OVER VERY COLD AIR TRAPPED NEAR THE
SURFACE. A MIXTURE OF FREEZING RAIN AND SLEET WILL OVERSPREAD THE
REGION FROM WEST TO EAST DURING THE AFTERNOON AS TEMPERATURES
GRADUALLY RISE THROUGH THE 20S AND TOWARD THE FREEZING MARK"
It I had seen this warning of the temperature inversion, we would not
done this flight!
Doing my logbook after the flight, I noticed that this flight
completed my 400th hour in 4 years. Paul Craig's "The Killing Zone"
book identified the dangerous zone being between 50-350hrs. I don't
really believe that I am safe being outside of this zone. Piloting is
lifelong learning experience. We were just being a bit too complacent
with our local flights. This incident was a great wakeup call.
Hai Longworth

[Jose]

> In setting up for landing, I tried to stay high and slipped in with
> only 10-degree flap. Over the fence, I was still pretty high and
> somewhat fast so I dropped to 20-degree flap and reduced power to near
> idle to make sure that I would not land long on the 3000 feet runway.
> The landing was good and I was able to turn left to Alpha taxiway right
> to our tie-down area.

Good work, but when iced up, (I hear) it's important not to make big
changes in airfoil when landing. The iced up wing is more sensitive
to such changes and the disturbed airflow may separate, leading to a
low altitude stall. I've never landed with ice, so all this is from
what I've heard and read (and seen in FAA videos); others will
certainly fill in.

It can sure happen quickly.

Jose
r.a.student trimmed
--
Freedom. It seemed like a good idea at the time.
for Email, make the obvious change in the address.

[Colin W Kingsbury]

"Jose" > wrote in message
m...
> > In setting up for landing, I tried to stay high and slipped in with
> > only 10-degree flap. Over the fence, I was still pretty high and
>
> Good work, but when iced up, (I hear) it's important not to make big
> changes in airfoil when landing. The iced up wing is more sensitive
> to such changes and the disturbed airflow may separate, leading to a
> low altitude stall.

As I understand there's an evolving body of thought that the real culprit in
many of these cases is a tailplane stall rather thna a wing stall. Flap
deployment seems to be a decisive factor in precipitating these. The fun
part is that if you get into one the recovery procedure is the
opposite--nose up--than for a wing stall. This was all in a recent AOPA
Pilot issue IIRC. All the more reason to avoid the situation in the first
place.

-cwk.

[Jay Honeck]

> The weather was perfect for flying yesterday morning, sunny,

Good job, Hai. A little ice goes a long ways toward making you want to be
on the ground.

The one time we ran into significant icing, we had been trying to flank a
cold front that stretched from Illinois to Mexico on a flight from Florida
to Iowa. We kept the cold front off our left wing the whole day, as we made
our way north, flying just far enough east to stay in the clear. When we
got to the "top" of the front, in Illinois, we momentarily penetrated a rain
shower that made our windshield go completely opaque just like *that* -- no
warning at all. It was quite a shock.

Luckily, as we descended toward the nearest airport the ice began
sublimating, and we were suddenly on the backside of the front in the clear,
cold air. With that, all was well -- but it's an experience we'll never
forget.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Bob Gardner]

Because ice accretion is inverse to the radius of the collecting surface,
you will have about three times as much ice on the leading edge of the
horizontal stabilizer compared to the wing's leading edge. Best current
guidance is to avoid flap extension if icing is suspected because of the
possibility of tailplane stall.

Other than that, you done good!!!

Bob Gardner

> wrote in message
oups.com...
> The weather was perfect for flying yesterday morning, sunny, mostly
> blue sky with about 12000' ceiling and little wind (unlike the day
> before when we canceled our flying plan due to 13G24 wind). As usual,
> we checked weather sites, TAF/weather map etc before heading to the
> airport. Bad weather is moving in but not until later in the day with
> 3000' ceiling at 3pm and light rain predicted at midnight or so. Our
> plan was just to do some local IFR training flights taking turns
> wearing foggles or acting as the safety pilot.
> After entering the gate, we glanced at the ramp and saw quite a bit
> of activities with several vehicles and a small group of people at the
> north side of runway 24. In closer look, we saw a plane landed off the
> runway in the grassy area with half of the wing stuck in a fence. We
> immediately thought that the accident was due to the gusty/windy
> condition the day before. It turned out that it was due to an engine
> trouble on take off, luckily the pilot walked away unarm. We saw both
> the pilot and the owner in the pilot lounge. Both looked quite grave
> and were busy checking AIG insurance policy on open pilot cause.
> We have always done a thoroughly preflight inspection and
> preparation but this incident made us double-checks everything. After
> plugging in the Reiff heaters and put on the nose mitten, Rick went and
> chatted with a friend who was preheating his with a propane tank. He
> also had a new engine and we both felt that preheating was needed even
> in temp near 40F. The was quite a lot of activities on the ramp and in
> the pattern in this relatively warm January weather. We went to the
> mall nearby to pick up some tools at Sears while the engine being
> heated. In checking the sky after our shopping, I was somewhat
> concerned of the overcast instead of earlier blue sky but Rick assured
> me that the ceiling should stay high enough for our practices.
> We had planned to take off at before noon, but all the activities
> added up and we did not depart until 1pm. The tanks were more than half
> full. We thought of topping off but to save time, Rick suggested that
> instead of flying northeast to Pawling VOR, he could do his practice on
> the way north to Columbia. We could fuel there and I could fly to
> Pawling on the swayback for my practice turn. ATIS at taxi time
> indicated 5000' ceiling with about 2C spread between temp and dew
> point.
> While Rick was under the hood, I noticed that both the ceiling and
> visibility seemed to get worse as we approached 1B1, so I suggested him
> to cut the practice short and just prepared to land. Columbia AWOS
> indicated wind at 200, 12 gusting to 18 (in contrast with 6 knots wind
> at Dutchess) and with only 1C spread between temp and dew point. We
> quickly fueled up, sumped the fuel, did a walk around inspection,
> listened to AWOS then took off again. Ceiling had lowered to 3500' and
> temp and dew point were both at 3C. I turned on the pitot heat and
> made sure that cowl flap was close and the engine was leaned. After
> about 15 to 20 minute under the hood, I heard Rick said in a somewhat
> alarming voice "Change your plan, we are heading back to Dutchess - It
> has started to rain". Then his raised his voice "Full throttle, full
> throttle, we have ice on the windshield". Rick immediately put on the
> defroster while I flipped on all our lights, landing/taxi/nav and
> double checked that the pitot heat was on, cowl flap close, carb heat
> off, engine leaned. We wanted the engine to kick off as much heat as
> possible. At the same time, I was also trying to descend to a lower
> altitude while keeping the speed just below the yellow arc. Rick wanted
> me to go down to 2000' both for warmer air and less headwind (we have
> something like 40' headwind at 3000') but I settled for 2500'thinking
> altitude was my friend. Rick told me the GPS showed the nearest airport
> was Kingston at 7nm and asked me whether I wanted to land there. Our
> encounter with freezing rain was quite brief probably less than a
> minute, because the windshield ice seemed to start melting where the
> defroster hit at the pilot's side and there was no evidence of
> additional ice build up. I had plenty of lift at full throttle, had to
> pull back the power to stay at 2500' and not getting in the yellow arc.
> I told Rick that I would continue south to Dutchess toward better
> weather. KPOU ATIS indicated ceiling of 4000' with 1C spread between
> temp and dew point. I contacted the tower for landing and also
> reported our light icing encountered. The tower told us that they would
> notify flight service. By this time, my side of the windshield was
> clear enough for VFR. In my vague recollection, I probably relied
> mostly on the instrument panel trying to keep straight and level,
> descent at steady rate, following the VOR radial back to KPOU. I have
> not officially started my instrument training but had done dozens of
> foggles hours and had just spent the entire week playing with my
> Christmas present, Elite v.8 with the IFR training manual. The
> practices really came in handy.
> In setting up for landing, I tried to stay high and slipped in with
> only 10-degree flap. Over the fence, I was still pretty high and
> somewhat fast so I dropped to 20-degree flap and reduced power to near
> idle to make sure that I would not land long on the 3000 feet runway.
> The landing was good and I was able to turn left to Alpha taxiway right
> to our tie-down area.
> The windshield was totally clear by the time we landed. I immediately
> got out and check the wings. They were still coated with a clear thin
> layer of ice which was melting quickly at 38F ground temperature.
> After my icing report to the tower, there were two planes taking off
> northbound. On our way out of the airport, we noticed several people
> standing near the ramp area having their picture taken. Rick stopped
> and asked whether they planned to go up soon. They nodded with big
> smiles. The pilot was on the ramp getting the plane ready. Rick told
> the passengers about the freezing rain/icing and suggested that should
> not go up. I am not sure whether they comprehend the danger of the
> situation by the look on their faces. I just hope that they would tell
> the pilot of our advice.
> In reviewing the incidence, we realized that we have made several
> small errors. First, we should leave a wider margin of time for the
> incoming bad weather. Secondly, we should not have changed our flight
> plan at the last minute. If we had planned to go north to Columbia, we
> would have paid closer attention to Albany TAF and weather report.
> After our flight, I checked my mail and found an urgent winter storm
> watch and warning for Albany region which remained in effect from noon
> to 5pm:
> "WARM MOIST AIR AHEAD OF A WARM FRONT MOVING INTO THE NORTHEAST FROM
> THE OHIO VALLEY WILL RIDE OVER VERY COLD AIR TRAPPED NEAR THE
> SURFACE. A MIXTURE OF FREEZING RAIN AND SLEET WILL OVERSPREAD THE
> REGION FROM WEST TO EAST DURING THE AFTERNOON AS TEMPERATURES
> GRADUALLY RISE THROUGH THE 20S AND TOWARD THE FREEZING MARK"
> It I had seen this warning of the temperature inversion, we would not
> done this flight!
> Doing my logbook after the flight, I noticed that this flight
> completed my 400th hour in 4 years. Paul Craig's "The Killing Zone"
> book identified the dangerous zone being between 50-350hrs. I don't
> really believe that I am safe being outside of this zone. Piloting is
> lifelong learning experience. We were just being a bit too complacent
> with our local flights. This incident was a great wakeup call.
> Hai Longworth
>

[steve.t]

The tail plane stall that all keep talking about, isn't it caused by
icing over a stablizer that is at or just below the plane of the wing?
Then when the flaps are deployed, the air is disturbed sufficiently
that the tail stalls?

Therefore, if flying a T tail (or similar), deployment of flaps should
not affect the tail. Is this correct?

I'm asking because of flying a Piper wherein the wing is actually below
the stabliator. Deployment of 15 degrees of flaps should not
sufficiently disturb the airflow to cause the tail plane stall in this
case. Is this correct?

Later,
Steve.T
PP ASEL/Instrument

ps. I'm almost at that 350hr mark some one else mentioned. T-storms,
fog and ice conditions are automatic no-go situations for me. Too much
at stake.

[Denny]

It is not just the flap deployment altering airflow over the stabilizer
that causes a tail plane stall - though that is a major problem for
many airplanes - but it is also the slowing up with flap deployment
which forces the horizontal stabilizer to fly at a higher angle of
attack (downward attack, of course)... So T-tails need to be flown
exactly the same way as straight tails... If the ship has a load of ice
(weight) forcing the airfoils to fly at a higher angle of attack to
begin with and the stab has ice distorting it's airfoil, then
increasing the angle of attack even further by slowing up will/can be
the final straw leading to an accelerated tail plane stall followed
instantly by the nose pitching downward sharply..... If you are iced
up, forget the flaps and keep the speed up until the wheels are just
above the runway... It is far better to deal with a possible low speed
over run off the end of the runway, than a pitch over at a few hundred
feet of altitude where death is certain...

Thunder bumpers, fog, and icing, are ABSOLUTE no-go situations for
me...

Remember this old saw, because it is absolutely true:
There are old pilots...
There are bold pilots...
But there are no old-bold pilots...

Denny

[[email protected]]

Bob,

Thank you very much for your tailplane stall explanation. We
attended a Wing Safety Seminar last November on Winter Operations where
it was mentioned but only in term of symptoms and recovery process. I
did not realize that there would be more chance of a tailplane stall
than wing stall due to heavier ice accumulation.

Before landing, I had discussed with my husband, Rick on whether I
should have landed with no flaps or with 10 degree flap. Since the
standard Cardinal takeoff procedure calls for 10 degree flap, we
thought it would provide more lift. We did not think of the possiblity
of tailplane stall. Although I had practiced landings with different
flap configurations every few months, I generally dislike the noflap
approach due to extremely nose high position. I hate not being able to
see a darn thing ahead while landing. The practices did come in handy
late last fall in our long cross country trip from New York to northern
Minnesota. Within an hour of flying, we had complete electrical
failuires due to a bad crimp job on one ot the alternator wires. We
have owned our plane for about 1 1/2 years and put over 200hrs on it.
It was our luck that we landed at Seaman airport and the folks at O&N
aviation (the home of the Silver Eagle) were open on Saturday. They
found the problem right away and get us going within few hours. The
owner did not write up a bill and told us just to give a tip to his
mechanics. Fantastic folks!. (Note to Jay: In our short flying
career, this was our first 'emergency' situation, the icing incidence
was the second. Luckily ;-) , I was the PIC in both cases and Rick
mainly offered assistance and did not insist on taking over. Just
wonder how you and Mary handle your flying responsibilities?).

On an aside note, for our instrument training, I bought at least
half a dozen books on the subject. Rick was ahead of me so he had
reviewed all of them. His main text book was your book, "The Complete
Advanced Pilot". He got 98 on his written and recommend me to start
right away with your book using others as supplemental readings. We
have also made good use of your "Say Again, Please" book. Thank you so
much for imparting your years of aviation skills, experiendce, wisdom
and insight to many next generations of pilots.
Best regards,
Hai Longworth

[[email protected]]

Denny,

Is is our modus operandi too. As I mentioned in my reply to Bob
Gardner, we attended the Wing Safety Seminar on Winter Operation last
November. Our thought was that we would never let it happen to us !
Little did we know that we would encounter icing in a short local
excursion on a day which we thought was perfect for flying. BTW, the
urgent weather warning which I received was through my-cast, a
'regular' and not aviation weather servcie. The TAF for Albany area
mentioned drizzle rain but much later in the day. POU TAFdid not
indicate any precipitation, 1B1 is between the two airports. The very
short duration of the freezing rain indicated that it could be very
local, just under a rain cloud. We might not have encountered it if
we were few miles East or West.

[Frank Ch. Eigler]

" > writes:

> [...] Before landing, I had discussed with my husband, Rick on
> whether I should have landed with no flaps or with 10 degree
> flap. [...] I generally dislike the noflap approach due to
> extremely nose high position. I hate not being able to see a darn
> thing ahead while landing. [...]

Next time this happens, consider not only landing flapless, but
touching down at well above normal stall airspeed, basically doing an
airliner (or floatplane still-water) style flying-to-the-ground
landing. The pitch angle won't be so high, and you won't be at the
mercy of the possibly nastier stall characteristics with ice on the
wings. You would need a longer runway.

- FChE

[[email protected]]

Steve,

Bob is correct, never, ever use flaps on landing if you have any ice on
the airplane, it does not matter a bit about the position of the
horizontal stabilizer. Flaps change the airflow in the area of the
tail and also move the center of lift aft, both of which increase the
angle of attack of the tail, moving it closer to the stalling angle of
attack should it have any ice at all.

You might want to go to NASA's website and find the information there
on icing and tailplane stalls; it's eyewatering. They also sell a DVD
of inflight footage of their testing. Also go to AVweb
(www.avweb.com), click on "columns" then on "The Pilot's Lounge" and
scroll down to the column on tailplane stalls. If you get IFR
Magazine, there is an article on dealing with inflight icing in the
November 2004 issue.

If in ice, leave the flaps up. Cessna POHs make this clear, I'm not
sure whether Piper POH's mention it. Touch down fast, and do NOT
reduce power at all until the wheels are rolling as the power reduction
may take you from flying at above the power on stall speed to
descending fast at below the power off stall speed.
All the best,
Rick

[[email protected]]

Rick,
I just checked my Cardinal POH and it does state leaving wing flaps
retracted.
I have few questions: for this particular case whether icing is
very mimimum (thin layer of clear ice) and the runway is relatively
short (3000') and there appeared no loss of any lift power, do you
think that I still should have used no flaps and no power reduction
until touch down?
Another question is with the cabin heat and defroster knobs? We left
both on full blast and the POH indicated the same thing but if we want
to melt the windshield ice quickly, shouldn't we close off the cabin
heat to divert all the heat to to the windshield area first?
Hai

[Bob Gardner]

AC 23.143-1, which deals with tailplane stalls due to icing, mentions tail
configuration as one of the considerations but does not distinguish between
T-tails and conventional tails in its advice to avoid flap extension if
icing is suspected. No free pass for T-tails or cruciform tails.

Bob Gardner

"steve.t" > wrote in message
oups.com...
> The tail plane stall that all keep talking about, isn't it caused by
> icing over a stablizer that is at or just below the plane of the wing?
> Then when the flaps are deployed, the air is disturbed sufficiently
> that the tail stalls?
>
> Therefore, if flying a T tail (or similar), deployment of flaps should
> not affect the tail. Is this correct?
>
> I'm asking because of flying a Piper wherein the wing is actually below
> the stabliator. Deployment of 15 degrees of flaps should not
> sufficiently disturb the airflow to cause the tail plane stall in this
> case. Is this correct?
>
> Later,
> Steve.T
> PP ASEL/Instrument
>
> ps. I'm almost at that 350hr mark some one else mentioned. T-storms,
> fog and ice conditions are automatic no-go situations for me. Too much
> at stake.
>

[Bob Gardner]

Thanks for the kind words, Hai. As is the case with all warnings about ice,
it is not the weight of the ice so much as the distortion of the airfoil due
to ice accretion. On final, chances are that the horizontal stab is going to
be tilted forward (leading edge down), improving the chances of ice
collection on the upper surface. Since the horizontal stab develops a
downward force, ice on the upper surface is the equivalent of ice on the
bottom of the wing's leading edge.

The problem with tailplane icing is twofold: First, you can't see it very
well and must assume the 3-to-1 ratio I mentioned before. Second, when the
tailplane stalls and the nose pitches down when flaps are extended, there is
no time to react. We had a commuter twin dive in from 600 feet over in
Eastern Washington a few years ago with no survivors.

The problem with icing, period, is that it is not predictable or repeatable.
Fly two airplanes through the same cloud at the same speed and the ice forms
will be different; fly the same airplane through the same conditions twice
and the ice forms will be different. The drawings of clear, mixed, and rime
ice in FAA publications don't even come close to reality. Scary stuff, to be
avoided at all costs.

Here is part of AS 23.143.1:

e. Ice Contaminated Tailplane Stall (ICTS). ICTS occurs due to airflow
separation on the lower surface of the tailplane that is caused by the
angle-of-attack of the horizontal tailplane being increased above the
reduced stall angle-of-attack that can result when even small quantities of
ice have formed on the tailplane leading edge. The increase in tailplane
angle-of-attack can result from airplane configuration (for example,
increased flap extension increasing the downwash angle or trim required for
the CG position) and/or flight conditions (for example, high approach speed
resulting in an increased flap downwash angle and reduced angle-of-attack,
gusts, maneuvering or engine power changes). ICTS is characterized by a
reduction or loss, sometimes sudden, of pitch control or stability while
operating in, or recently departing from, icing conditions. For airplanes
with longitudinal control systems that are not powered (reversible control
systems), the pressure differential between the upper and lower surfaces of
the stalled tailplane may result in a high elevator hinge moment, forcing
the elevator trailing edge down. This elevator hinge moment reversal can be
of sufficient magnitude to draw the control column forward with a level of
force that is beyond the combined efforts of the flightcrew to overcome. On
some airplanes, ICTS has been caused by a lateral flow component coming from
the vertical stabilizer, as may occur in sideslip conditions or due to a
gust with a lateral component. An evaluation should be made to determine if
this unsafe flight condition is likely to occur. Susceptible airplanes are
those having a near zero or negative stall margin with contamination. Flight
test procedures for determining susceptibility to ICTS are included in AC
23.143-1, "Ice Contaminated Tailplane Stall (ICTS)".


Bob Gardner



> wrote in message
oups.com...
> Bob,
>
> Thank you very much for your tailplane stall explanation. We
> attended a Wing Safety Seminar last November on Winter Operations where
> it was mentioned but only in term of symptoms and recovery process. I
> did not realize that there would be more chance of a tailplane stall
> than wing stall due to heavier ice accumulation.
>
> Before landing, I had discussed with my husband, Rick on whether I
> should have landed with no flaps or with 10 degree flap. Since the
> standard Cardinal takeoff procedure calls for 10 degree flap, we
> thought it would provide more lift. We did not think of the possiblity
> of tailplane stall. Although I had practiced landings with different
> flap configurations every few months, I generally dislike the noflap
> approach due to extremely nose high position. I hate not being able to
> see a darn thing ahead while landing. The practices did come in handy
> late last fall in our long cross country trip from New York to northern
> Minnesota. Within an hour of flying, we had complete electrical
> failuires due to a bad crimp job on one ot the alternator wires. We
> have owned our plane for about 1 1/2 years and put over 200hrs on it.
> It was our luck that we landed at Seaman airport and the folks at O&N
> aviation (the home of the Silver Eagle) were open on Saturday. They
> found the problem right away and get us going within few hours. The
> owner did not write up a bill and told us just to give a tip to his
> mechanics. Fantastic folks!. (Note to Jay: In our short flying
> career, this was our first 'emergency' situation, the icing incidence
> was the second. Luckily ;-) , I was the PIC in both cases and Rick
> mainly offered assistance and did not insist on taking over. Just
> wonder how you and Mary handle your flying responsibilities?).
>
> On an aside note, for our instrument training, I bought at least
> half a dozen books on the subject. Rick was ahead of me so he had
> reviewed all of them. His main text book was your book, "The Complete
> Advanced Pilot". He got 98 on his written and recommend me to start
> right away with your book using others as supplemental readings. We
> have also made good use of your "Say Again, Please" book. Thank you so
> much for imparting your years of aviation skills, experiendce, wisdom
> and insight to many next generations of pilots.
> Best regards,
> Hai Longworth
>

[Blueskies]

> wrote in message oups.com...
> Rick,
> I just checked my Cardinal POH and it does state leaving wing flaps
> retracted.
<snip>
> Hai
>


Original Cardinals had problems with horizontal tail stall, thus the slot on the LE. I can only imagine landing one iced
up...

[SP3]

"steve.t" > wrote in message
oups.com...
> The tail plane stall that all keep talking about, isn't it caused by
> icing over a stablizer that is at or just below the plane of the wing?
> Then when the flaps are deployed, the air is disturbed sufficiently
> that the tail stalls?
>
> Therefore, if flying a T tail (or similar), deployment of flaps should
> not affect the tail. Is this correct?
>
> I'm asking because of flying a Piper wherein the wing is actually below
> the stabliator. Deployment of 15 degrees of flaps should not
> sufficiently disturb the airflow to cause the tail plane stall in this
> case. Is this correct?
>
> Later,
> Steve.T
> PP ASEL/Instrument
>
> ps. I'm almost at that 350hr mark some one else mentioned. T-storms,
> fog and ice conditions are automatic no-go situations for me. Too much
> at stake.


The tailplane stall, in the iceing case, is caused by leading edge
contamination by ice.
The scenerio goes something like this:
Leading edge ice causes less tail lift (or tail download ) to be available
at at particular elevator angle. To maintain trim the pilot flies with an
increased elevator angle. When flaps are selected the nose down pitching
moment (NOT TRIM CHANGE) is controlled by more elevator deflection. In the
iceing case this extra elevator deflection may cause the tailplane alpha to
exceed the stalling angle (with ice). Tail download is then much reduced
and the aircraft pitches nose down uncontrollably.
My experience with tailplane stall in a turboprop twin (during flight test)
is that the pitch down is sudden and dramatic - 0g or less, a height loss
of 1500 to 2500 ft, and usually overspeed gear and flaps. In this case the
elevator hinge moments reduced markedly and full aft stick could be easily
applied but with no effect. Recovery was rapid if the airflow re-attached
to the tailplane with full aft stick applied ie very easy to overstress the
aircraft.
Cheers,

[[email protected]]

Geez, it's amazing how things become old wives tales. Only a small
number of the very first model 177s (original 1968 model year
airplanes) left the factory before it was noticed that with full flaps
and when slipping toward a landing the pilot could experience an
intermittent "tug" on the control wheel. It was traced to the airflow
over the stabilator in those conditions and the stabilator nearing the
stall angle of attack. It was decided to put the slots in the
stabilator to allow it to fly at a higher angle of attack. It solved
the problem. The ones in the field that didn't have them were modified
and all subsequent airplanes (rest of the 177s, all of the 177As and
177Bs) left the factory with the slots. It also resulted in removing
the recommendation against slips with full flaps from the Owner's
Manual.

Totally separate issue from tailplane stall in icing.
All the best,
Rick

[[email protected]]

Hai,

You've just defined the classic icing problem for general aviation
airplanes: the need to come down final fast, with flaps up, toward a
runway that isn't terribly long and may be contaminated. (Get the
November issue of IFR Magazine for a long discussion on it). On top of
things, you need to allow a little altitude over the threshold if there
is any snow in the area because the plow driver may have piled snow at
the end of the runway (which is not appropriate but sometimes happens).


Once you get any ice whatsoever on the airplane you become a test
pilot. At some point you will have enough that if you deploy the flaps
the tail will stall and the airplane will pitch down radically...as has
happened on a number of well-publicized commuter crashes. As a result,
you don't know what the wing and tail are doing, so the only safe
approach is to fly final fast, flaps up, with power (I owned a 117B
Cardinal for a while and would come down final at 90-100 knots, flaps
up, if I had ice). You don't know when the wing will stall, either.
On the times I had to land the airplane with ice, I set up so that I
would be in a position to see whether there is any snow pile at the end
of the runway, and then land as near the threshold as conditions
permit, flare slightly (at that speed with flaps up the airplane is
pitched up anyway, so you don't need to worry about landing on the
nosewheel) and put the wheels on the ground. Close the thottle
immediately on touchdown and gently start applying the brakes to see
what you've got. If the runway is contaminated, it's going to be
challenging to keep the airplane straight and get it stopped. In 3,000
feet you should be able to do so unless it's icy. The reality is that
you may go off the end of the runway. However, you have just been in a
classic emergency: the airplane is iced up and you were at risk of
loss of control while in the air at 90-110 knots; the impact from that
would probably be fatal. If the choice is a loss of control at 100
knots or sliding off the end of a runway at 20 knots, I'll take the low
speed impact every time. That's why we have insurance.

With ice, avoid setting up high on final; when you have an emergency
try to make everything else as normal as possible, so that you see a
sight picture that is consistent with what you are used to. The
problems I've seen include pilots who are high on final and don't touch
down in the first part of the runway and then try to go around with a
load of ice. It doesn't work. Set up for a normal approach, just
fast. In fact, practice some no flap landings so it's not a new
experience when you have to do it for real.

Yes, get the defroster going full blast. You may even want to block
off the copilot's defroster to put more on your side of the windshield.
Divert all cabin heat to the defroster if you can. In the Cardinal
you can also open the little window on your side at approach speed and
use it to help you see forward. Yes, the cold air and snow or rain
coming in won't be fun, but the idea is to see the runway.
All the best,
Rick

[Jay Honeck]

>(Note to Jay: In our short flying
> career, this was our first 'emergency' situation, the icing incidence
> was the second. Luckily ;-) , I was the PIC in both cases and Rick
> mainly offered assistance and did not insist on taking over. Just
> wonder how you and Mary handle your flying responsibilities?).

We have discussed this issue at length, and we handle cockpit resource
management in the same way you do. Whoever is in the left seat is
pilot-in-command, and has absolute authority to make decisions. (This, of
course, doesn't stop us from offering advice or making snide remarks about
certain landings... :-)

The right seater is only allowed to take the controls in the event of an
emergency that threatens imminent danger. In Mary's 500 or so hours, I've
taken the controls just once from the right seat, and that was when a NORDO
Stinson tried to trade paint with us in the pattern. The plane was coming
in from behind Mary's left shoulder, in her blind spot, and breaking hard
right seemed the wise thing to do.

It was sheer luck that I spotted it at all. As the Stinson flew through the
spot we had just occupied, moments before, Mary didn't argue!

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[[email protected]]

Rick,
I was quite lucky to have a safe landing inspite of my complacency
and naivety. Since my windshield had became clear and there was no
apparent loss of lift, I assumed that I could almost land 'normally'.
I did have some concerns about not being to perform a go-around hence
the decision to drop 20 degree flap and reduced power after crossing
over the fence to make sure that I would not have landed long.

If I had realized the potential for tailplane stall and the
unpredictability of icing condition, I would have been more cautious
and woud have seeked out better options. I could have asked the tower
for a longer runway (rwy 24 with 5000'). The crosswind was quite mild
(only 6 or 7 knots! The Cardinal has no trouble handling 15-20 knots
xwinds). The other option is to fly to KSWF just across the river but
with 9600' runway.

The valuable advices that I received here from you, Bob and others
along with an email that I received today from FAA RON on Ice
contamination (quoted below) gave me a healthy respect for ice!

"Greetings, This is important info. NTSB Issues Warning on Wing Ice
As a result of its ongoing investigation of the Nov. 28, 2004 fatal
takeoff accident involving a Challenger 604 in Montrose, Colo., the
NTSB
on December 29 issued a special alert involving the detection and
effects of ice accumulation on the wing. "It has become apparent that
many
pilots do not recognize that minute amounts of ice adhering to a wing
can
result in severe control penalties," the Safety Board said. "Some
pilots believe that if they cannot see ice or frost on the wing from a
distance, or maybe through a cockpit or cabin window, it must not be
there-or if it is there and they cannot see it under those
circumstances, then
the accumulation must be too minute to be of any consequence."
Despite
evidence to the contrary, the NTSB emphasized, "These beliefs may
still
exist because many pilots have seen their aircraft operate with large
amounts of ice adhering to the leading edges and consider a thin layer
of ice or frost on the wing upper surface to be more benign."
However,
the Safety Board noted, "Research has shown that small amounts
of ice accumulation on the upper surface of a wing can result in
aerodynamic degradation as severe as that caused by much larger (and
more
visible) ice accumulations." Fine particles of frost or ice, the size
of a
grain of table salt and distributed as sparsely as one per square
centimeter over a wing's upper surface, can destroy enough lift to
prevent
an airplane from taking off, according to the agency. "The bottom
line
is that pilots should be aware that no amount of snow, ice or frost
accumulation on the wing upper surface can be considered safe for
takeoff."
..

[Blueskies]

> wrote in message ups.com...
> Geez, it's amazing how things become old wives tales. Only a small
> number of the very first model 177s (original 1968 model year
> airplanes) left the factory before it was noticed that with full flaps
> and when slipping toward a landing the pilot could experience an
> intermittent "tug" on the control wheel. It was traced to the airflow
> over the stabilator in those conditions and the stabilator nearing the
> stall angle of attack. It was decided to put the slots in the
> stabilator to allow it to fly at a higher angle of attack. It solved
> the problem. The ones in the field that didn't have them were modified
> and all subsequent airplanes (rest of the 177s, all of the 177As and
> 177Bs) left the factory with the slots. It also resulted in removing
> the recommendation against slips with full flaps from the Owner's
> Manual.
>
> Totally separate issue from tailplane stall in icing.
> All the best,
> Rick
>

Horizontal tail effectiveness and tailplane stall just the same...There were instances of landing gear damage due to
hard landings by folks running out of elevator that was attributed to this also. Don't get me wrong, the 177 RG (or no
RG) is a fine instrument platform and a fine flier.

BTW, I may be getting old but I am not an old wife! ;-)

[[email protected]]

Indeed, you are not an old wife, and are not old...age is a state of
mind <g>.

In fact, there were no instances of landing gear damage due to hard
landings in the Cardinal due to "running out of elevator" yet another
old wive's tale; the nosewheel damage incidents on Cardinals were due
to the extremely effective stabilator (Cardinal stabilators are
effective to far lower speeds than virtually any other general aviation
airplane, which is why they have the longest c.g. range of any four
place airplanes ever made). Pilots overcontroled in the flare - where
they were used to airplanes that lost elevator effectiveness at low
speeds, the Cardinal did not, and PIO was the result as pilots moved
the yoke fore and aft and the airplane responded very rapidly in pitch.
The upshot was that the pilot either went around or hit hard on the
nosewheel due to his yoke inputs. That's why any prepurchase
inspection of a Cardinal includes a careful examination of the firewall
for wrinkles to see if the nosegear has been smacked and the repairs
not done correctly. Source: Aviation Consumer Used Airplane Buyer
Guide and 1,500 hours in Cardinals as PIC and flight instructor as well
as NTSB reports on Cardinal accidents. Interestingly, Cardinal
nosewheel damage accidents started to decrease in the mid '70s when the
Grumman Traveler, Cheetah and Tiger series came out and had an
extremely effective elevator at low speed .... but also suffered from
nosewheel impacts and bent firewalls.

In the late '80s I was involved in a series of flight tests on
Cardinals for reasons that would take too long to go into here, the
interesting thing was that the airplanes could do some amazing things
and had much more responsive controls than others in the general class
- as a result, they could handle much stronger crosswinds than other
nosewheel airplanes and had some pretty amazing low speed handling
abilities, with pitch, roll and yaw rates that could be induced near
the stall that were much faster than the Cherokee 180/Archer, Cessna
172/182 and Beech Musketeer/Sierra series. The downside was that most
pilots weren't trained to handle a responsive airplane, which lead to a
higher than average incident rate, particularly on landing. You
probably know all that as you fly a 177RG, which has impecable manners
and is a ball to land in very strong crosswinds when everyone else has
hidden behind the hangar.

All the best,
Rick