MAYDAY in the Everglades

Marty from Sunny Florida wrote:

The sky was clear, and when I got my pre-flight briefing, the temp was 26
and dew point 16. It was unseasonably cool and very dry for Florida. At
altitude, I knew the air had almost no moisture, but on the way up, we did
have a typical hazy layer.

Temp 26 and dewpoint 16 puts you well outside the icing region on this chart:

http://www.ez.org/carb_ice.htm

The temperature at altitude was probably well below 26, but even so you seem to
be pretty well outside the temperature / dewpoint danger zone.

Nevertheless, I agree with the consensus that carb ice is the best explanation.

I'm mystified that the chart doesn't confirm.

Dave

On 5/4/2005 08:20, Dave Butler wrote:

Marty from Sunny Florida wrote:

The sky was clear, and when I got my pre-flight briefing, the temp was 26
and dew point 16. It was unseasonably cool and very dry for Florida. At
altitude, I knew the air had almost no moisture, but on the way up, we did
have a typical hazy layer.

Temp 26 and dewpoint 16 puts you well outside the icing region on this chart:

http://www.ez.org/carb_ice.htm

I assumed the temperatures provided by the original poster were in
centigrade. That puts the temp at 79 deg F and the dew point at 61 deg F.

Assuming 2 deg C drop per thousand feet, that puts the temperature
at 57 deg F and the dew point at 35 deg F. Very close to the blue
"Icing at glide and cruise power" band.


The temperature at altitude was probably well below 26, but even so you seem to
be pretty well outside the temperature / dewpoint danger zone.

Nevertheless, I agree with the consensus that carb ice is the best explanation.

I'm mystified that the chart doesn't confirm.

Dave


--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA

Mark Hansen wrote:
On 5/4/2005 08:20, Dave Butler wrote:

Marty from Sunny Florida wrote:

The sky was clear, and when I got my pre-flight briefing, the temp
was 26
and dew point 16. It was unseasonably cool and very dry for Florida. At
altitude, I knew the air had almost no moisture, but on the way up,
we did
have a typical hazy layer.


Temp 26 and dewpoint 16 puts you well outside the icing region on this
chart:

http://www.ez.org/carb_ice.htm


I assumed the temperatures provided by the original poster were in
centigrade. That puts the temp at 79 deg F and the dew point at 61 deg F.

Assuming 2 deg C drop per thousand feet, that puts the temperature
at 57 deg F and the dew point at 35 deg F. Very close to the blue
"Icing at glide and cruise power" band.

You're right. I did the unit conversion correctly on one axis, but somehow
muffed the other axis. Thanks.

I'm extremely impressed with the response I've gotten to this post. I know
as a given fact that I will not get hurt in a general aviation aircraft that
I'm flying during daylight hours. It's just a fact that comes with a great
respect for the unexpected (I have a healthy fear of what I don't know). I'm
a pre-flight nut case. I sump the fuel always, even after a 10 minute stop
without re-fueling. The plane has an almost zero time status (now at 125
hours since major OH). I'd had an oil change a couple of days earlier and
wondered if my mechanic had nicked the fuel line, or in some odd manner made
a change to the fuel system, but that didn't and still doesn't make sense.

Regarding my flight plan- I have been tossed out of Miami's Bravo airspace
about as often as girls turned me down when I was a teenager. Not being shy,
that's a lot. The only choice is over the ocean below 3,000, over MIA's
airspace at 7,000 or the swamp to the west. I take the swamp because it's
quiet (except for a few minutes when the big jets are turning final while
West of MIA). At all times I check to make certain I have enough altitude
(except when climbing out, of course), to make solid ground. This time I
knew I could make the interstate, but would truly choose this as a last
resort. The NTSB would get involved, and I'd have to get the plane trucked
out of the everglades. To save my wife and I, I would do this in a
heartbeat. My preference, of course, would be to put down at an airfield,
which I did.

Someone asked me what I'd do differently, and my wife and I have discussed
this several times since Friday. The answer comes up every time - Nothing. I
did and would still do exactly as before, but probably swap the first thing
= full rich to first thing = carb heat. Other than that, no other change. I
didn't touch the mags for concern I'd kill the engine. A dead mag will rob
you of power, but it won't cause a rough sputter. I've been trained to make
as little change to a failing engine as possible. Even an aiplane that's
lost it's oil will continue to fly a lot longer if you don't touch the
throttle or mixture. It's when you make a change that an opportunity to
seize occurs. I did, however, push and poke everything else (or what litter
there is to push in a C152).

My wife who's not a pilot, but spends a lot of time in the right seat
telling me where to go, concluded carb ice. She did this when we first
touched down at Dade-Collier airport. My mechanic on the phone explained
that a bad cylinder wouldn't fix itself, but water in the tanks would
eventually blow through the system. The mechanic I met on the ramp also said
bad fuel. My buddy and CFI back in Lantana (I called everyone), said bad
gas. My wife insisted carb ice.

So whadayall' say. Should I give my pilots license to Lynda or what?

Marty

Marty from Florida wrote:

I didn't touch the mags for concern I'd kill the engine.

I agree with you completely. Switching to one mag would help only in a situation
in which a mag has jumped time. Your description of the symptoms doesn't match
what happens when a mag's mistimed (backfiring usually comes into the picture in
this case). I would not have touched the ignition switch.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.

"Marty from Florida" marty@-x-x-x- remove -x-x- worth.net writes:

[...] I know as a given fact that I will not get hurt in a general
aviation aircraft that I'm flying during daylight hours. It's just a
fact that comes with a great respect for the unexpected (I have a
healthy fear of what I don't know). [..]

I hate to say this, but all that respect and pre-flight attention is
just not a guarantee that you won't be hurt. There are unfortunately
many ways to get hurt in an airplane, some foreseeable, some
preventable, and some neither. I don't want to scare you by dreaming
up scenario after scenario, but rest assured that they exist.

- FChE

You should show this story in RAS. I think it is a good story for student
pilots to hear.

Toks Desalu
PP-ASEL
"Dyin' to soar"

"Marty from Sunny Florida" wrote in message
...
Hello everyone.



The end of my story is this; We landed safely in the middle of the Florida
Everglades and didn't get a single Alligator bite. Here's what happened;



On Friday, April 29th, we took our Cessna 152 from Lantana, Florida to the
center of the State for gas and start our trek south to Key West. The
total
journey is a little over 2 hours.



Forty five minutes after filling with gas in Pahokee, we were just below
Alligator Alley (highway 75). Our engine hiccupped. A few minutes later,
it
hiccupped again, this time losing a couple of hundred RPM. We were at
6,800
feet, strait and level flight running at 75% power (about 2350 RPM). The
mixture had been leaned back about 30 minutes earlier, and none of the
engine instruments had changed from the time we made our cruise altitude.



As the hiccups got closer together engine power dropped off significantly,
grabbing our total attention. My first move was pulling up on the yoke to
maintain altitude. I trimmed to our plane's best glide of 60 kts When the
sputtering became a constant rough drone, the engine still held some
power,
and we could see nothing but marsh. I though about the choice between
ditching in green or brown muck, not sure where the biggest alligators
live.
There was absolutely no solid ground as far as the eye could see.
Solemnly,
I rolled the 'standby' frequency to 121.5 acknowledging the severity of
our
predicament.

Acting on the premise that the engine could quit at any moment and our
best
option was behind us on highway I75, I started a very gentle 180 degree
turn.



Oil pressure was in the green. Oil temp was in the green. Mags were on
BOTH.
The fuel showed close to full (I had at least 18 gallons useable). My only
immediate change was to push the mixture to full rich, which had no
effect.
When I touched the throttle to add power, the RPM dropped. Gently, I
returned the throttle and the power evened out.



The sky was clear, and when I got my pre-flight briefing, the temp was 26
and dew point 16. It was unseasonably cool and very dry for Florida. At
altitude, I knew the air had almost no moisture, but on the way up, we did
have a typical hazy layer. My next move was carb heat, even though there
was
absolutely no visible moisture. It did smooth out the roughness slightly,
but did nothing for the power loss.



The engine was dying, and the math was simple. Sink at 500 fpt, 6,800 feet
gives me about 13 minutes and at 60 kts, I'd get about 15 statute miles. I
knew I could make the highway without an engine.



I've personally had experience looking for downed aircraft in the Florida
swamp, and know how difficult it is to spot a small plane. We needed to
let
someone know our position and situation. We had the skill to find the
closest airport but every moment was precious. ATC could save valuable
minutes and that might make the difference. With this in mind, I hit the
radio's flip-flop button and announced our tail number on the emergency
frequency.



The Controller was a true professional. He asked me a few questions and
instructed me to "ident" before assigning a squawk code. The radio
reception
was not clear, which generated a stream of "say agains". This, of course
added to the general stress of the situation.



Efficiently, he ascertained our position and vectored me to the
Dade-Collier
airport, which is in the middle of nowhere. Ironically, so were we! The
strip was 17 miles to our southwest, which is farther than a dead engine
would take me. We had been heading due north to a safe landing point on
I75
when ATC advised us to turn our backs on the hwy and return south. In my
heart, we turned away from solid ground to face only swamp again. I
decided
to trust fate and the ATC controller as I asked the alligators to gift me
the extra minutes of engine power needed to make the airport.



Trimmed back to slow flight, we managed to barely maintain altitude. We
arrived at the 10,500 foot runway with 3,200 feet of altitude and 120 kts
of
air speed. I figure I could have made 4 complete turns around the pattern
and still land hot. I have never been so relieved in my entire life.



On the ground, we taxied to an area near two other planes. Relieved and
curious I did a runup and the engine gave a text book performance.



Our cell phones didn't work so we called the FBO on the radio. We were
invited into the small building nearby where there was a phone. There we
learned that the other two planes had landed the day before with similar
symptoms.



I phoned my mechanic and relayed the story. He gave me some great advice
and
a definite suggestion about what caused the problem. We returned to the
plane to follow my mechanics instructions.



Another mechanic, who had come to pick up one of the other downed planes
kindly offered to look at my engine. He pulled the cowl open, checked the
cables on the throttle, carb heat and mixture. He sat in the 152 with me
while I did a regular and then full-power run up. The engine showed great
response to throttle, the mixture choked it and the carb heat performed as
advertised.



This qualified mechanic was planning to fly out in a plane that landed in
the same condition as ours. They offered us a ride if we were not
comfortable flying our 152. We had options. Now, we had to make a decision
to take the ride or hop in our plane and head out.



The logic was: someone at some point would fly our 152 out, and we would
again need to fly this same plane at some point ourselves. If we waited,
what would be different? A qualified mechanic not only said it was safe,
but
was flying out a plane in the same condition. We decided the problem had
resolved itself. We would fly.



After a lengthy check, we headed for the runway. I did a steep climb over
the field, continued uphill after completing a long, slow circuit of the
airport, and headed north with a 500 FPM climb. All the while, I knew I
could glide back to the runway if needed.



It was late to start our day in the Keys so we turned towards home. When
We
sighted I75, I knew I was home free. If there was trouble we were
guaranteed
a level spot to land. We made Lantana at full power with no sign of the
earlier problem.



I must say, I am impressed with the FAA system and the people who dedicate
their careers to the safety of our skies. This system that trains and
relies
on the good judgment of the individual pilot also supports the decisions
necessary in crisis. While part of the mandate of the FAA is to enforce
the
laws, a pilot's decisions are respected even when they are examined. I
find
great comfort in the FAA and the service it provides to general aviation.



If our highways resembled our skies, perhaps the average driver would be
less likely to knowingly break the law.



Here's my question to this group. What caused the engine failure? More
than
one thought is welcome, but please explain your answer. I have one of two
possibilities in my head, and invite any questions, advise, opinions, or
wisdom.



Warm regards from one very happy pilot.



Marty

I've had real bad carb ice two times in a C-150 on perfectly clear
days. Both times the conditions were similar to yours. One time at
6500 feet; one time at 8500; about 70 degrees on the ground and about
42-44 at my cruising level each time, and also in the south. I got
detailed weather information from Shaw AFB WX after I got back each
time which showed relative humidity at my cruising altitude was just
over fifty percent on both occasions, despite the beautiful clear skies
and great visibility. This is when carb ice sneaks up on you and hits
you hard, leaving you shocked and in disbelief, trying other solutions
and cursing your mechanic.

One time the carb heat cured the situation very quickly, the other it
took quite a while and I had to keep adjusting mixture. When you have
carb ice the mixture changes as the ice builds up and again as it melts
away which sometimes has you "chasing" the engine with throttle and
mixture manipulations to keep it running.

I didn't read all the other posts and it may have been mentioned
already but it's important to get full throttle in right away when
dealing with carb ice also.

In 3000 hrs flying mostly small piston planes I've learned to
immediately pull carb heat full out and leave it out at any burble,
hesitation, slow down or silence! Once you've got the carb heat
engaged, go to full throttle if you haven't already and adjust mixture
for best power -- you may have to keep adjusting the mixture several
times as the shape of your venturi/level of blockage changes from ice
melting or, (GASP) growing because your carb heat is inop or
insufficient.

- Brett Justus, ATP, G/S MEI/CFII, ASC