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Sunday, Nov 28 1992 Today my wife and I journeyed from the San Francisco Bay Area to Van Nuys,
California (near Los Angeles) to visit my
oldest brother, whom I hadn't seen in almost 10 years. I had canceled
this trip two weeks ago because of horrendously high winds and severe
turbulence in Southern California.
DUATS for the past 24 hrs showed a weak system moving in from the Pacific. My route (OAK-PXN-AVE-FIM-VNY)
forecast called for bottoms of 3,000 and tops at 7,000. Freezing level was at
13,000. Conditions were forecast to improve southward. All in all, not a bad
forecast. I filed for 7,000, the MEA over the first half of the route. Although I had
gotten my IFR ticket wet by flying in and out of Hayward, CA, these
were really just brief jousts with our pervasive costal stratus.
Therefore, today's trip would be my first experience with sustained en-route IMC.
We launched at 0935 into light rain and fog, and were solidly in the
muck at 2500. I was vectored around the Bay for several minutes
before being released on my own navigation and turned over to Oakland Center. This added up to about 30 minutes in IMC . This
was my wife's first time in IMC and she was already tired of
being inside the cotton ball. For her benefit, I asked Center if he knew
where the tops were. He gave the old nod-nod-wink-wink
reply, "No sir, but 9,000 is available if you want it." My wife held a
thumb up in front of my scan, and I accepted 9,000. The cabin started
brightening at 7500 and by 8,000 we were on top.
Once on top I tidy up: lean carefully, trim, turn off aux
pump, strobes, pitot heat, etc. After a few
minutes I noticed that the tops ahead were higher, so I
requested and got 11,000. After another five minutes (about 15 nm
north of the Pinoche VOR (PXN), I noticed that the tops ahead were again higher. This
time, though, instead of a solid ridge of clouds across our path, it
looked as if there were a single large cloud whose tops appeared to be about
15,000. The cloud seemed very thin, diaphanous almost, and I fully expected pop through
it in a matter
of seconds.
Immediately upon entering this beast, I felt a strong thump and up we
went. The airspeed indicator pegged at 2,000 fpm. In a flash we were at 12,200. I
reduced power about 300 rpm and pushed the nose down gently;
this provided a slight descent. Center now complained about my
altitude. I confessed and promised to correct. I heard the airplane about
five miles ahead of
me (at 13,000) nervously say , "Center, 41-Romeo is picking up ice and losing airspeed;
request diversion to the east over lower terrain." Center approved his
diversion.
At almost that instant my wife said, "Oh, look at the windshield." It
was completely covered and opaque with ice. The tops of the wings
are painted white, so it was difficult to see the clear ice, but it
in just the right light it was obvious. Then in a matter of seconds the airspeed indicator went from 125 knots to 0 knots. "Gee,
I've read about this before," I thought in a strangely detached way.
"This is the way folks die--icing up and stalling from excess weight
and no lift." The thought of perishing was short-lived, however, as my
survival instincts told me to "work the problem." This is probably
overstating my rational instincts; in fact, two
things argued against catastrophe: first, the drop in indicated airspeed had
been too precipitous; second,
for a stalled airplane, the Tiger was doing a hell of holding
altitude.
Just then I remembered that I had earlier switched the pitot heat off
when I broke out on top. I switched it back on and went back to my
scan. The gentle descent had decayed into level flight at about 12,500.
Without an airspeed indicator I didn't dare fight the updraft more rigorously. As
quickly as it had departed, the airspeed indicator returned--indicating about 105
knots. Noting that I had lost about 30 knots of airspeed in straight
and level, I pulled the power back to the bottom of the green and
pointed the nose down another dot. This established a 500 fpm
descent.
Although it was reassuring to know that I was still flying, I wanted
down--NOW! "Center, 613's picking up ice and requests an immediate
descent to 9,000." There was a pause, then, "613, I have your request;
descent unavailable at this moment. Expect lower in 6 miles."
Is this what a PIREP means when it refers to
"light" icing? Maybe I'm a flying glacier, poised to fall from the
sky in the next instant. With zero experience with ice, and in the
absence of positive information to the contrary, I decided to assume
the worst. "Center, 613 requests vectors to the nearest VFR." I
paused, not anxious to cry wolf, then added, "This is an urgent request." I was
prepared to used the E-word if necessary, and probably should have.
"Roger, 613. Standby." He had been providing VFR advisories to a
Cessna 182 about five miles behind me to the west. "613, suggest right turn
to 270 and a descent to 7,000." I put in a standard rate turn as soon
as I heard the word "right." This was about a 160 degree turn, and
it seemed to take forever. I kept the rate of descent at about 500
fpm just in case I was carrying a lot of ice. At 8,500 the ice on the
windshield began to break up--but still no VFR. What I heard next--loud thunks from the front of the plane--made me think that the
plane was coming apart. After a few moments, however, I assumed that these
must be the sounds of the prop shedding ice against the nose-bowl.
At 8,000 I spotted the ground, applied power, and began a gentle, shallow
spiral. What seems to me to be huge sheets of ice began to melt and
creep back on each wing. The sound of ice from the prop increased. I
informed Center that I'm in VFR and shedding the ice. He asked whether
I'd be continuing on my route IFR or VFR. I told him that I'd advise.
After a couple of circles there was no more evidence of ice. I was still VFR, but just ahead
lay the cloud bank I had just done battle with. What the hell--I'll proceed
on course IFR, but I'll stay low--out of the ice. I apply full power, raise the nose, and am
about to key the mike to talk to Center when I notice something odd:
although
I'm pitched for 90 knots, I'm only climbing at 50 fpm or so; the Tiger usually gives about
400 fpm here. I think about carburetor ice, but the RPM is normal.
Now what? The performance degradation isn't likely due to a downdraft, so I
guess that I might
still be carrying ice--a lot of ice--on surfaces I can't see. If so, the last thing I wanted was to re-enter IMC
in that condition.
With my my shirt soaked with perspiration, my spectacles fogged, and
feeling mentally wrung out, I decided I'd had enough excitement
for one day. "Center, 613 will cancel IFR, and request VFR flight
following to Van Nuys."
We descended to 5,500--just under the clouds--and proceeded uneventfully to a CAVU Van Nuys. Over the next few minutes the
airspeed indication returned to normal.
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