OK, Luke, Here's More Numbers for You

" jls" wrote:
Furthermore, homebuilts have an enviable safety record,
!?!
Enviable by whom - Evel Knievel?
Let's have real numbers when discussing these things;
Indeed.
--
Dan
C-172RG at BFM

Check this out, Danny:

http://www.seqair.com/FlightTest/Kil...lYourself.html
Some people want to fly faster than that 130 mph Cessna of yours or in a
different or unique airplane, and they don't have the experience in the type
chosen for the purpose. I knew a doctor who killed himself in a Monnett Moni
because he didn't have any time in it; the flight was the aircraft's (and
his) first and last.

Check out the graph here too:

http://www.provide.net/~pratt1/ambuilt/faqhmblt.htm
Experimentals are here to stay. Their safety record, just as the safety
record of GA aircraft, always needs improving, but your comment is
irresponsible.
If you have any numbers other than sneering, please provide them.

Hope this helps.

" jls" wrote:
http://www.seqair.com/FlightTest/Kil...lYourself.html

From the article:
"Overall the safety record of homebuilt aircraft is not greatly
different from production aircraft."

The author provides no evidence. Where are the numbers?

Some people want to fly faster than that 130 mph Cessna of yours

That's a 155 mph Cessna, son.

[snip]

Check out the graph here too:

http://www.provide.net/~pratt1/ambuilt/faqhmblt.htm

What part of the graph has anything to say about the safety numbers of
homebuilts?

Experimentals are here to stay.

Really? Gosh!

[snip]

If you have any numbers other than sneering, please provide them.

Experimentals comprise 10.4% of the GA fleet
http://makeashorterlink.com/?U1842322A but, according to the 2003 ASF
Nall report, historically produce 17% of the fatal accidents. From the
report:

"Comparison with Factory Aircraft:
In 2002, homebuilt airplanes were involved in 196 accidents. Of these,
60 fatal accidents resulted in 79 fatalities. Factory-built airplanes
in 2002 were involved in 1,276 accidents, of which 252 were fatal with
439 fatalities. Just over 30 percent of homebuilt aircraft accidents
resulted in fatalities, and 19.7 percent of the accidents in
factory-built airplanes were fatal. As in prior years, it appears that
there is a significantly higher risk of fatality in the event of an
accident in a homebuilt aircraft compared to a factory-built machine.
Although fatal homebuilt aircraft accidents decreased dramatically in
2000, they increased to 19.2 percent in 2002. Historically, homebuilt
aircraft are involved in approximately 17 percent of all fatal
accidents."

Hope this helps.

Ditto.
--
Dan
C172RG at BFM

In a previous article, "Dan Luke" said:
If you have any numbers other than sneering, please provide them.

Experimentals comprise 10.4% of the GA fleet
http://makeashorterlink.com/?U1842322A but, according to the 2003 ASF
Nall report, historically produce 17% of the fatal accidents. From the
report:

The biggest weakness with the Nall report, and one which they admit in the
report itself, is that they don't have "per flight hour" figures. If home
builders are more likely to get out and fly their aircraft rather than let
them sit mouldering with weeds growing through the landing gear, than the
higher proportion of accidents means nothing. On the other hand, if the
non-experimentals get flown on long distance night IFR while the
experimentals get flown for local $100 hamburger runs, those figures might
be covering up a much worse accident rate.

We'll probably never really know the true answers, until somebody makes a
long term comprehensive study of hours flown and types of flying versus
accidents across the whole fleet.

--
Paul Tomblin http://xcski.com/blogs/pt/
Microsoft - Where quality is job 1.0.1

On Fri, 31 Dec 2004 18:25:27 +0000 (UTC), (Paul
Tomblin) wrote:

In a previous article, "Dan Luke" said:
If you have any numbers other than sneering, please provide them.

Experimentals comprise 10.4% of the GA fleet
http://makeashorterlink.com/?U1842322A but, according to the 2003 ASF
Nall report, historically produce 17% of the fatal accidents. From the
report:

The biggest weakness with the Nall report, and one which they admit in the
report itself, is that they don't have "per flight hour" figures. If home
builders are more likely to get out and fly their aircraft rather than let
them sit mouldering with weeds growing through the landing gear, than the
higher proportion of accidents means nothing. On the other hand, if the
non-experimentals get flown on long distance night IFR while the
experimentals get flown for local $100 hamburger runs, those figures might
be covering up a much worse accident rate.

We'll probably never really know the true answers, until somebody makes a
long term comprehensive study of hours flown and types of flying versus
accidents across the whole fleet.

Ahem. KITPLANES magazine, October 2004.

Ron "self-plugging" Wanttaja

Ron Wanttaja wrote:

We'll probably never really know the true answers, until somebody
makes a long term comprehensive study of hours flown and types of
flying versus accidents across the whole fleet.

Ahem. KITPLANES magazine, October 2004.

How about a brief summary for those of us who don't subscribe? One
wouldn't expect a magazine of that title to be completely unbiased
about such a subject, but even biased information can be useful.
Jim Rosinski

Jim Rosinski wrote:

Ron Wanttaja wrote:


We'll probably never really know the true answers, until somebody
makes a long term comprehensive study of hours flown and types of
flying versus accidents across the whole fleet.

Ahem. KITPLANES magazine, October 2004.


How about a brief summary for those of us who don't subscribe? One
wouldn't expect a magazine of that title to be completely unbiased
about such a subject, but even biased information can be useful.
Jim Rosinski


The brief summary is that amateur built experimental airplanes are more
dangerous than their spam can counterparts.


Matt

On 31 Dec 2004 11:38:32 -0800, "Jim Rosinski" wrote:

Ron Wanttaja wrote:

We'll probably never really know the true answers, until somebody
makes a long term comprehensive study of hours flown and types of
flying versus accidents across the whole fleet.

Ahem. KITPLANES magazine, October 2004.

How about a brief summary for those of us who don't subscribe? One
wouldn't expect a magazine of that title to be completely unbiased
about such a subject, but even biased information can be useful.

A brief summary is tough, when we're talking a 3000+ word article with a bunch
of graphs (I was the author of the article).

The biggest problem with a summary is that it's tough to include all the
cautions and caveats about the input data used. I can't guarantee the results
the article show are accurate, except within the framework of the data and
assumptions used. I've had several email exchanges with folks who didn't agree
with some of the assumptions I used. That's fine...*that's* why I explained my
processes in the article.

But on a summary... it's tough to make it clear where errors could have been
introduced. Given a couple of days, I can probably get the entire article
online. But let me give what summary I can, now.

The study was based on homebuilt aircraft accidents from 1998 to 2000,
inclusive. I downloaded the full NTSB accident summaries for each of those
years. For each accident involving a homebuilt, I studied the narrative and
made my *own* assessment of the cause of the accident. I did the same for
Cessna 172 and 210 accidents (to provide a baseline of comparison of causes). I
referred to these as "Accident Initiators," leaving the phase "Probable Cause"
to the NTSB.

In addition, I already possessed the FAA Registration databases for July 1997
and January 2001. I determined the average "fleet size" for homebuilts and for
the total US registered aircraft for the 1998-2000 time period.

This leads to one problem with the input data. Each registry entry includes a
field for an Airworthiness Classification code. This code will be "1" for a
Standard Category aircraft, "2" for Limited category, "3" for restricted, "4"
for Experimental, and so forth.

Supposedly, this code is assigned when the airplane receives an airworthiness
certificate. Unfortunately, this doesn't always happen with homebuilts...I've
found a number of operational aircraft that have a blank in this field. I've
also found a number of aircraft still under construction that *do* have an
entry.

A while back, I did a step-by-step analysis of the FAA registration database,
and found about 4000 aircraft with "homebuilt-like" names, that have
airworthiness column blank. How many of these airplanes are currently flying?
No one knows. But the FAA and EAA *only* count aircraft that are positively
indicated as Experimental, and have the appropriate code in another column that
indicates that they are Experimental Amateur-Built aircraft. These are also the
only planes *I* counted in my analysis...basically because there was no reliable
way to tally the unmarked aircraft.

With that said: My analysis showed an average annual fleet accident rate of
1.05% for homebuilt aircraft, and 0.68% for all US-registered aircraft. The
Cessna-alone rate was probably more indicative of the GA rate, that was 0.72%.

If homebuilt aircraft during their first 40 hours of flight are eliminated from
the homebuilt accidents, the overall homebuilt rate drops to 0.85%.

Of more interest was determining the accident rate on a per-hour basis. There
are no real figures available. I attempted to approximate this, using the NTSB
accident reports. They include the model year of the accident aircraft, the
date of the accident, and the total time at the time of the accident. I used
these figures to determine the average hourly rate for various types of
aircraft.

Of importance was not, so much, the actual magnitude of the figures, but the
*relative* magnitude, between the two types of aircraft.

But this method had problems as well. It's easy to figure what "1972" in the
model year column means for a Cessna 150...but what does it mean for a
homebuilt? Was it the first year it was registered (which might be ten years
before the first flight), or the predicted completion date, or the actual date
the airplane made its first flight?

But I ran the figures. I came up with an average annual utilization rate for
homebuilts of around 55 hours. For single-engine, fixed-wing, non-agricultural
aircraft, the rate was about 155 hours per year. It results in homebuilts having
a accident rate per 100,000 flight hours about five times higher than the GA
average.

I'm personally skeptical of this figure. I think if one could extract the
*equivalent* operations from the production-aircraft accidents...e.g, only
aircraft that were personally owned and operated (homebuilt can't be rented,
etc.), I think the comparative figures would be closer to the fleet rate.

I'm skeptical of the five times higher rate... but that's the way my numbers
came out, that's what I put in the article, and that's what KITPLANES magazine
printed.

I'll probably do some work and get the whole article online in a bit.

Ron Wanttaja

Ron Wanttaja wrote:

We'll probably never really know the true answers, until somebody
makes a long term comprehensive study of hours flown and types of
flying versus accidents across the whole fleet.

Ahem. KITPLANES magazine, October 2004.

How about a brief summary for those of us who don't subscribe? One
wouldn't expect a magazine of that title to be completely unbiased
about such a subject, but even biased information can be useful.
Jim Rosinski

Are you talking about your 172RG? Do they really cruise at 155 MPH? I
thought they cruised around 145 MPH. Is yours modified?

I'm asking because I'm looking to buy one.


"Dan Luke" wrote in message
...

" jls" wrote:
http://www.seqair.com/FlightTest/Kil...lYourself.html

From the article:
"Overall the safety record of homebuilt aircraft is not greatly different
from production aircraft."

The author provides no evidence. Where are the numbers?

Some people want to fly faster than that 130 mph Cessna of yours

That's a 155 mph Cessna, son.

[snip]

Check out the graph here too:

http://www.provide.net/~pratt1/ambuilt/faqhmblt.htm

What part of the graph has anything to say about the safety numbers of
homebuilts?

Experimentals are here to stay.

Really? Gosh!

[snip]

If you have any numbers other than sneering, please provide them.

Experimentals comprise 10.4% of the GA fleet
http://makeashorterlink.com/?U1842322A but, according to the 2003 ASF Nall
report, historically produce 17% of the fatal accidents. From the report:

"Comparison with Factory Aircraft:
In 2002, homebuilt airplanes were involved in 196 accidents. Of these, 60
fatal accidents resulted in 79 fatalities. Factory-built airplanes in
2002 were involved in 1,276 accidents, of which 252 were fatal with 439
fatalities. Just over 30 percent of homebuilt aircraft accidents resulted
in fatalities, and 19.7 percent of the accidents in factory-built
airplanes were fatal. As in prior years, it appears that there is a
significantly higher risk of fatality in the event of an accident in a
homebuilt aircraft compared to a factory-built machine. Although fatal
homebuilt aircraft accidents decreased dramatically in 2000, they
increased to 19.2 percent in 2002. Historically, homebuilt aircraft are
involved in approximately 17 percent of all fatal accidents."

Hope this helps.

Ditto.
--
Dan
C172RG at BFM

" wrote:

Are you talking about your 172RG? Do they really cruise at 155 MPH? I
thought they cruised around 145 MPH. Is yours modified?

According to Clarke's book, cruise for a 172RG at 75% power is 161 mph.

George Patterson
The desire for safety stands against every great and noble enterprise.