Icing tape - lessons learned.

[Capt. Geoffrey Thorpe]

"Jay Honeck" > wrote in message
ups.com...
> This is the audio tape of a Fed Ex Caravan pilot who tangled with some
> severe icing conditions.
>
> http://www.alexisparkinn.com/photogallery/Videos/2007-1-26_N1278L-Mayday.mp3
>
> (It's a good-sized .mp3 file, so be patient while it downloads...)
>
> This was given to me by our local FAA safety guy, to share with our
> airport user's group. The stark terror in her voice is chilling, and
> really points out how quickly things can go bad.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"

Ok, since the previous thread has degenerated into a urinating contest about
the tone of the pilots voice - I will start a new thread in an attempt to
discuss what could be learned from this incident. (And, yes I was one of
the guilty parties.)

1) I suspect (knowing nothing beyond what I heard) that the pilot failed to
recognize the ice buildup untill control was lost. I ASSUME that she was in
the soup at the time - so the lesson here is pay attention - it's cold, you
are in the clouds, look out the window and watch for ice. Right?

2) Don't give up the ship. Even after loosing control, loosing lots of
altitude, etc. She kept fighting, figgured out what was wrong, applied the
appropriate counter measures (boots and heat - albeit a bit late) and got it
back. She also managed to give the "look out below" warning to ATC.

3) Instruments lie. It sounds like the peito (how the heck do you spell
that - I've tried a dozen different ways and none of them look right) froze
(she said she couldn't control airspeed). Knowing that she had a load of ice
would, I think, make one suspect the IAS and I would think that the sound
and feel of the aircraft should have helped her realize that the actual
airspeed was OK? Of course the ice would have effected the handling and made
it more difficult to know exactly what was lying to her. A quick switch to
alternate static might have been in order (She may or may not have done
that) or a cross check with GPS (which I assume she had) might have been a
good idea too (she may or may not have done that also).
How do you know WHICH instrument is lying to you? You have to ignore your
inner ear, but sound and feel?

What else?

Disclaimer - I ain't never flown with anything more than a hint of ice (the
rain drops stopped moving on the windscreen). And I've never flown in IMC or
with de-ice equipment.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Peter R.]

On 2/6/2007 6:28:30 PM, "Capt. Geoffrey Thorpe" wrote:

> 3) Instruments lie. It sounds like the peito (how the heck do you spell
> that - I've tried a dozen different ways and none of them look right)

pitot

--
Peter

[Peter R.]

On 2/6/2007 6:28:30 PM, "Capt. Geoffrey Thorpe" wrote:

> A quick switch to
> alternate static might have been in order (She may or may not have done
> that) or a cross check with GPS (which I assume she had) might have been a
> good idea too (she may or may not have done that also).
> How do you know WHICH instrument is lying to you? You have to ignore your
> inner ear, but sound and feel?
>

I replied too fast. To comment on your above: I have had my pitot heat fail
during night IMC flight through wet snow in a Bonanza V35. The first
indication to me that there was a problem was that the airspeed indication
slowly but noticably fell from my cruise of 165 its to 140 and continued to
fall.

The first thing I did was check the GPS ground speed to confirm my speed was
still roughly the same as it had been throughout the flight. I then
double-checked and recycled my pitot heat switch to see if perhaps the switch
was not on (it was) or had faulted. With indicated airspeed still falling, I
then swiped the circuit breakers to see if one had popped - None did.

With those cross checks, I came to the conclusion that the pitot heat itself
must have failed and therefore ignored the ASI. This was confirmed after I
landed by the touch test.

Alternate static won't help a frozen or otherwise blocked pitot tube, BTW.

In regards to the pilot of the Caravan, her brain was already oversaturated
by the crisis of the aircraft stalling and falling. It is understandable to
me that her brain did not register that perhaps the pitot heat was not on or
had failed. I had the luxury of only having to deal with that one problem;
the Caravan pilot had a much bigger problem on her hands.

Sound and g-forces are a good secondary indication that the aircraft is in an
unusual attitude, but I am pretty confident that I would not be able to
recover my aircraft by sound and g-forces alone. In her case, again, her
aircraft was probably unrecoverable for a short period due to icing and
perhaps a misconfigured autopilot (a/p was probably flying the majority of
the leg and was allowed to take the aircraft into the stall due to icing
before the pilot noticed), so her instruments, other than her ASI, were not
lying to her. I am surmising that it wasn't until she reached warmer air,
released the a/p, and lost some of the ice that she was able to recover.




--
Peter

[Peter R.]

On 2/6/2007 6:55:26 PM, "Peter R." wrote:

> In her case, again, her
> aircraft was probably unrecoverable for a short period due to icing and
> perhaps a misconfigured autopilot (a/p was probably flying the majority of
> the leg and was allowed to take the aircraft into the stall due to icing
> before the pilot noticed),

Sorry, I should have written: misconfigured TRIM due to a/p...

--
Peter

[JGalban[_14_]]

Peter R. wrote :
>With those cross checks, I came to the conclusion that the pitot heat
itself
>must have failed and therefore ignored the ASI. This was confirmed
after I
>landed by the touch test.

A good way to troubleshoot pitot heat is to watch the ammeter when
you switch it on. Most pitot heat systems have a hefty current draw,
which is readily apparent when you turn it on. No movement on the
ammeter generally equates to no heat.

I also use the ammeter to check my landing light whenever I turn it
on (it's out in front where I can't see it).

John Galban=====>N4BQ (PA28-180)


--
JGalban
Posted at www.flight.org

[Capt. Geoffrey Thorpe]

"Peter R." > wrote in message
...
> On 2/6/2007 6:28:30 PM, "Capt. Geoffrey Thorpe" wrote:
>
<...>.
>
> Alternate static won't help a frozen or otherwise blocked pitot tube, BTW.

Right. But if you aren't sure what the problem is...

>
> In regards to the pilot of the Caravan, her brain was already
> oversaturated
> by the crisis of the aircraft stalling and falling. It is understandable
> to
> me that her brain did not register that perhaps the pitot heat was not on
> or
> had failed. I had the luxury of only having to deal with that one problem;
> the Caravan pilot had a much bigger problem on her hands.
>

No kidding. Gotta give her credit for pulling her butt out of the fire.

> Sound and g-forces are a good secondary indication that the aircraft is in
> an
> unusual attitude, but I am pretty confident that I would not be able to
> recover my aircraft by sound and g-forces alone.

I would agree. I was just thinking if sound and G were "ok" then perhaps it
may have pointed to the airspeed as the bad actor.


> In her case, again, her
> aircraft was probably unrecoverable for a short period due to icing and
> perhaps a misconfigured autopilot (a/p was probably flying the majority of
> the leg and was allowed to take the aircraft into the stall due to icing
> before the pilot noticed), so her instruments, other than her ASI, were
> not
> lying to her. I am surmising that it wasn't until she reached warmer air,
> released the a/p, and lost some of the ice that she was able to recover.

It isn't clear from the tape at what point she switched on the anti-ice, but
she did say she had an OAT of 0 C. after she leveled off - doesn't sound
like a lot of "natural" melting happened. But I could be wrong.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[BDS]

"Capt. Geoffrey Thorpe" <The Sea Hawk at wow way d0t com> wrote

> 1) I suspect (knowing nothing beyond what I heard) that the pilot failed
to
> recognize the ice buildup untill control was lost. I ASSUME that she was
in
> the soup at the time - so the lesson here is pay attention - it's cold,
you
> are in the clouds, look out the window and watch for ice. Right?

Always a good idea - use your flashlight at night to check. Also, keep in
mind that the wings may be the least efficient ice collector on your
particular airplane - the tail may be much more efficient (Mooney as one
example) and be icing up nicely while you see almost nothing on the wing.
So, while you're looking for ice be sure to take a glance back at the tail
too, assuming you or your pax can see it. Tailplane stalls can be a huge
bummer.

BDS

[Marco Leon]

On Feb 6, 9:19 pm, "BDS" > wrote:

> Always a good idea - use your flashlight at night to check. Also, keep in
> mind that the wings may be the least efficient ice collector on your
> particular airplane - the tail may be much more efficient (Mooney as one
> example) and be icing up nicely while you see almost nothing on the wing.
> So, while you're looking for ice be sure to take a glance back at the tail
> too, assuming you or your pax can see it. Tailplane stalls can be a huge
> bummer.

I thought the same thing. The tailplane ice would explain the "out of
control" situation as opposed to an even set of airframe ice and its
associated gradual decline in performance. If the main wings built up
so much ice as to stall and lose control, it would strike me as
unrecoverable or at least severe enough to not allow her to talk on
the radio.

Marco

[BDS[_2_]]

"Marco Leon" > wrote

> I thought the same thing. The tailplane ice would explain the "out of
> control" situation as opposed to an even set of airframe ice and its
> associated gradual decline in performance. If the main wings built up
> so much ice as to stall and lose control, it would strike me as
> unrecoverable or at least severe enough to not allow her to talk on
> the radio.

I didn't listen to the tape but the descriptions that mentioned a sudden out
of control dive sure sound like a tailplane stall to me. It can take a
tremendous amount of force on the yoke to recover, and recovery technique is
not intuitive because it is not the same as the technique(s) used for a
normal wing stall.

NASA has a nice tape on tailplane icing that is well worth watching.

BDS

[Nathan Young]

I think the lesson is stay aware of icing conditions, and if you must
absolutely fly in/near icing conditions - you better put the airframe
into the instrument scan.

Icing cannot be ignored, but that is precisely what this thread has
hypothesized.

First, the Caravan was flying in an area near icing. Strike One.

Second, this thread has hypothesized that the pilot failed to use
pitot heat, boots, and/or let the autopilot fly the plane into the
stall. Strikes 2,3,4.

Avoiding any one of these items likely would have precluded the
incident.

[Dylan Smith]

On 2007-02-07, BDS > wrote:
> I didn't listen to the tape but the descriptions that mentioned a sudden out
> of control dive sure sound like a tailplane stall to me. It can take a
> tremendous amount of force on the yoke to recover, and recovery technique is
> not intuitive because it is not the same as the technique(s) used for a
> normal wing stall.

Other nasty things can happen in icing too. You may remember the
incident with the ATR in Roselawn, Indiana (which has a substantially
similar airfoil to a Caravan, I'd imagine). Ice built up behind the
area behind the deicing boots in a ridge. The aircraft was on autopilot.
When the autopilot disconnected, the ailerons underwent a "hinge moment
reversal" - so instead of wanting to remain neutral, snapped to full
control deflection very suddenly. The plane went inverted, and the crew
split-S'd out of it. Unfortunately, the aircraft disintegrated during
the split S from the G forces.

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

[Mike Young]

"Peter R." > wrote in message
...
> On 2/6/2007 6:28:30 PM, "Capt. Geoffrey Thorpe" wrote:
> In regards to the pilot of the Caravan, her brain was already
> oversaturated
> by the crisis of the aircraft stalling and falling. It is understandable
> to
> me that her brain did not register that perhaps the pitot heat was not on
> or
> had failed. I had the luxury of only having to deal with that one problem;
> the Caravan pilot had a much bigger problem on her hands.

I'm not convinced anything at all happened, except she got disoriented
trying to make sense of her failed instruments, and then "recovered" from
stable, level flight into a diving, screaming series of over reactions and
recoveries. (Ask me how I know. And then tell me how is it you were spared
this particular learning experience. :)