Accident Data

[Hank S]

An ongoing discussion about carb heat and proper usage brought up a question. One poster mentioned a 20-year-old copy of an AOPA Air Safety Foundation Safety Report that showed but one accident attributed to carb ice in the thirty year period reviewed.

Is more recent data available, without having to dig through the Nall Report looking for it? Any analysis available on carb ice accidents? I know of one, the plane I trained in about three years after I finished up. Wondered how many others there are, frequency, severity, etc.

Associated question: what's a good number on the Carb Heat Gage when using partial carb heat? Actually, what number to activate at, and what number to raise to. Mine has an orange stripe from -10 to +10°C. Others have Carb Heat on engine monitors, but no such stripe there. I pull enough in IMC to stay above the stripe; don't recall ever seeing it below the stripe, but flying VFR in WV, I didn't pay it much attention. Often had OATs around -10°C.

Thanks, ya'll!

 

[wanttaja]

An ongoing discussion about carb heat and proper usage brought up a question. One poster mentioned a 20-year-old copy of an AOPA Air Safety Foundation Safety Report that showed but one accident attributed to carb ice in the thirty year period reviewed.

Is more recent data available, without having to dig through the Nall Report looking for it? Any analysis available on carb ice accidents? I know of one, the plane I trained in about three years after I finished up. Wondered how many others there are, frequency, severity, etc.

I don't have any overall GA numbers, but I have analyzed some aircraft types for accident causes.

From January 1998 through December 2010, I show about 1600 Cessna 172 accidents. Twenty-four were either directly attributed to carb ice, or occurred in conditions conducive to icing with no other engine failure cause found.

From January 2000 to December 2010, there were about 600 accidents involving the PA-28-140, -161-, -180, and -181 models. Twelve involved carburetor icing.

From January 1998 to December 2014, there were about 3500 accidents involving Experimental Amateur-Built aircraft. 68 involved carburetor icing.

You can download the complete NTSB aircraft accident database at:

http://app.ntsb.gov/avdata/Access/avall.zip

Be advised it's about 250 MB.

Ron Wanttaja

 

[Hank S]

Wow! You're on the ball tonight, Ron! Fifteen minutes with an answer, and data.

Thank you.

 

[Non Compos Mentis]

A problem with carb ice incidents:

The evidence melts before the investigators arrive. We can guess that carb ice may have been a cause, or even just a factor, but the proof is long gone.

 

[wanttaja]

Wow! You're on the ball tonight, Ron! Fifteen minutes with an answer, and data.

Just the luck 'o the log-in; checking the forum just a few minutes after your post. I've got spreadsheets with the data summarized, so getting the answer was just a couple of clicks.

Ron Wanttaja

 

[wanttaja]

A problem with carb ice incidents:

The evidence melts before the investigators arrive. We can guess that carb ice may have been a cause, or even just a factor, but the proof is long gone.

Frank T. Courtney was an early pre-WW-I aviator who wrote "The Eighth Sea", his autobiography of his life in aviation from bamboo crates to the Atlas missile.

He was in a cross-country race where his engine mysteriously quit. He landed without damage. He pulled the cowl and started checking the engine when a big chunk of ice dropped down out of the updraft carb.

As you say, most carb-ice accidents are denied even this sort of physical evidence. For the most part, I believe the investigators consult the temperature and humidity conditions to determine the likelihood of carb ice. In some cases, the pilots admit they didn't use carb heat, or the plane doesn't have a working carb heat control.

Otherwise, I think they tend to attribute the failure to carb ice if the charts say a high probability of its occurence and there's nothing else wrong with the engine. In some cases, they're able to restart the engine afterwards, so it was probably carb ice or vapor lock.

Ron Wanttaja

 

[OkieAviator]

Interesting info... still going to keep pulling carb heat on with every landing regardless.

 

[bobmrg]

Interesting info... still going to keep pulling carb heat on with every landing regardless.

Can't go wrong doing that. I can't upload the whole thing, but the National Transportation Board wrote this recommendation to the FAA on January 8, 1990 (Refer to "A-89-140 through -142" (...good luck with that):

"in the pilot’s operating handbooks and airplane flight
manuals of carburetor-equipped airplanes to require the
use of full carburetor heat when engine power is reduced
below the normal cruise power range (the green arc on
the tachometer or the manifold pressure gauge), or below
an alternate engine power setting as determined by the
manufacturer. "

Their goal in making this recommendation was to drive a stake through the idea of different procedures for different engine manufacturers. The FAA never acted on the recommendation.

Bob Gardner