Emergency

It was the 3rd leg of an Angel Flight and I wasn't even supposed to be
flying it. I'd already flown the second leg from Natchez, MS to
Monroeville, AL, but the 3rd leg pilot had mysteriously failed to show--no
call, no nothin'. It was late, I was tired and I was mad. I had two pax
aboard.

We were in the clouds and in the dark in a Cutlass RG approaching Macon, GA
(MCN). The outside temperature was 13 C and moisture was streaming back on
the windshield. The throttle was fully open, the RPM was set for 2500 and
the mixture was leaned to 10.5 gph. The autopilot was holding course and
altitude. I was studying the ILS approach plate when I noticed the AP's
"up" trim warning light illuminate.

A quick scan of the instruments showed the IAS at 100 and falling; normally
it would indicate 125 at that altitude. I had detected no change in the
engine sound. I immediately hit the AP disable switch to prevent its
stalling the airplane. This was right and wrong, as I now had to do all the
flying while troubleshooting the problem. What I should have done was
disable the altitude hold and allow the AP to continue keeping us on course
and wings level.

Any attempt to lift the nose resulted in a sickening drop in airspeed. The
situation was now officially scary: we were going down on a dark, rainy
night over central Georgia.

I shoved the prop and mixture full forward, confirmed the throttle was wide
open and the primer was in. No improvement. There was no unusual
vibration. The engine still sounded good and was still making 2500 rpm, but
the prop was probably in flat pitch to do it. I tried the electric fuel
pump: no joy. I glanced at the JPI engine analyzer and saw that all four
cylinders showed roughly even EGTs. All this took much less than a minute;
maybe only 30 seconds.

Finally, I pulled the carb heat. Within a few seconds I felt a surge of
power and we began to climb. I don't know for sure what a death row inmate
feels like when the governor calls at the last minute, but I'm guessing it
feels something like that.

My heart was pounding in my chest and I was so stoked on adrenalin my hands
were shaking. The front seat passenger was looking at me wide-eyed--he
didn't know what was happening, but he had figured out *something* wasn't
right. I had wandered 40 deg. off course and Atlanta Approach was repeating
a frequency change instruction. In a few moments I had us back on course
and altitude but I was still somewhat rattled and blew the readback on
Atlanta's initial approach instructions. Got that sorted out and made an
uneventful ILS approach to runway 5 at MCN.

Not a totally satisfying performance. I ended up doing the right thing and
we lived; that's the good news. The bad news is that allowed myself to rush
things. A moment's thought would have prevented the autopilot mistake. A
calmer, more orderly flow through the engine controls would have led me to
the carb heat sooner and saved a few unnecessary extra seconds of high
anxiety. Next time I have an emergency (please: NO next time!) I'll try to
take it a little slower.

I'm still surprised that the carb iced up at full throttle. Conditions were
in the bad area of the carb ice chart, but my engine has never seemed prone
to the problem. In 650+ hours I've only detected carb ice once before, and
that was after a long taxi on a cool, rainy day.

--
Dan
C172RG at BFM