Cirrus... is it time for certification review?

"Happy Dog" wrote in message
m...
"Dave Stadt"
One might say that the fatal accident rate seems disproportionate (50%
of the SR20, 25% for the SR22 versus 10% for the 172 and 20% for the
182), but at the sample sizes present, there's absolutely no
reasonable way to draw any valid statistical conclusion (and note that
for the SR22 and the 182, the rates are actually similar).

Apples and oranges. The 182 fleet is many times larger than the SR22
fleet. And the 172 fleet is near infinite compared to the Cirrus fleet.
The numbers look pretty bad for Cirrus.

Did you adjust for the kind of flying done by each? No, you didn't.

The flights all involve an equal number of takeoffs and landings only
some are more successfull in the landing department than others.

Unless you wish to redefine "flight" , no, they don't. Are circuits
"flights"?

moo

I suspect so. Unless one just motors around on the ground in a big
rectangle.

Although the SR-22 is fixed gear wouldn't it be more appropriate to
compare them to other planes of similar performance and wing loading?
Then remove the "gear up" incidents for the final comparison?

When it comes to performance and handeling the SR-22 is about as far
from a 172 as you can get. I don't know of any "every day" retracts
like the Bo, or Mooney with near the wing loading of the SR-22 and
the 172 can be over 26% less than those at a tad over 14# per sq ft.

Actually both the Mooney and Bo are far easier to slow down even with
the tendency to float by the Mooney and they have roughly 30% less
wing loading than the SR-22.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Peter Duniho" wrote

A quick NTSB database search shows in the last six months 4 accidents (2
fatal) involving a Cirrus SR20, and 52 (5 fatal) involving a Cessna 172. The
SR22 was involved in 7 accidents (2 fatal), while the Cessna 182 was involved
in 36 (6 fatal).

Clue - Look at fleet size, then adjust for that, and come back with some more
meaningful statistics.

How many bazillion C172's are there out there, vs. Cirrus?
--
Jim in NC

"Morgans" wrote in message
...
Clue - Look at fleet size, then adjust for that, and come back with some
more meaningful statistics.

The fleet size isn't nearly as relevant as total flight hours for the flight
over a span of time. And yes, I agree that the data is missing. However,
none of you have provided alternate data to support the claim that the
Cirrus is actually worse. And at first glance, the total number of Cirrus
accidents is MUCH lower than for Cessna accidents, which is exactly what one
would expect given the difference in fleet sizes.

Clue: when you are making accusations, the burden of proof is on YOU. If
you're going to claim that the accident rate is abnormally high, you need to
provide data to support that claim. Suggesting that the defense has
insufficient data isn't meaningful.

Pete

Morgans wrote:
"Peter Duniho" wrote

A quick NTSB database search shows in the last six months 4 accidents (2
fatal) involving a Cirrus SR20, and 52 (5 fatal) involving a Cessna 172. The
SR22 was involved in 7 accidents (2 fatal), while the Cessna 182 was involved
in 36 (6 fatal).

Clue - Look at fleet size, then adjust for that, and come back with some more
meaningful statistics.

How many bazillion C172's are there out there, vs. Cirrus?

One thing these figures seem to say is that 50% of SR20 accidents are
fatal, but only 10% of 172 accidents are. It is only a bit better if
you compare both Cirrus and Cessna types. The parachute should make
Cirrus accidents more survivable, not less.


John Halpenny

On 31 Oct 2006 17:28:21 -0800, "John Halpenny"
wrote in .com:

One thing these figures seem to say is that 50% of SR20 accidents are
fatal, but only 10% of 172 accidents are. It is only a bit better if
you compare both Cirrus and Cessna types. The parachute should make
Cirrus accidents more survivable, not less.

What's the SR20's stall speed compared to the C-172? The kinetic
energy expended in a mishap increases exponentially with the square of
the velocity.

"John Halpenny" wrote in message
oups.com...
One thing these figures seem to say is that 50% of SR20 accidents are
fatal, but only 10% of 172 accidents are.

As I pointed out previously, there aren't enough SR20 accidents (or even
SR20 and SR22 combined) to make any valid statistical conclusions. The
statistical error on the sample size exceeds the number of samples.

Pete

Recently, Peter Duniho posted:

A quick NTSB database search shows in the last six months 4 accidents
(2 fatal) involving a Cirrus SR20, and 52 (5 fatal) involving a
Cessna 172. The SR22 was involved in 7 accidents (2 fatal), while the
Cessna 182 was involved in 36 (6 fatal).

One might say that the fatal accident rate seems disproportionate
(50% of the SR20, 25% for the SR22 versus 10% for the 172 and 20% for
the 182), but at the sample sizes present, there's absolutely no
reasonable way to draw any valid statistical conclusion (and note
that for the SR22 and the 182, the rates are actually similar).

The fact is, none of these airplanes are actually involved in fatal
accidents all that often, and the absolute numbers for overall
accidents are significantly lower for the Cirrus types than for
comparable Cessna types (of course, with a presumably much smaller
fleet size, that's to be expected, even without accounting for
differences in utilization).

Without the total fleet numbers, it is difficult to establish a
proportionate accident rate, but there is face validity to the notion that
the Cessna accident rate is far lower than Cirrus', given other methods of
comparison such as time flown per type or number of TOs & Landings.
Looking only at the type of accidents, one may conclude that pilot error
is the primary cause for either make of plane.

Neil




So, it seems to me that before we start throwing around statements
like "the problem is with the pilots, not the airplanes", it ought to
be established that there *is* a problem in the first place.

Pete

On Fri, 27 Oct 2006 18:26:33 -0400, "Kyle Boatright"
wrote:


"john smith" wrote in message
...
With the recent spate of Cirrus accidents, the question arises, "Is it
time for a special certification review?"


Any aircraft has a baseline accident rate. I think the Cirrus has a higher
accident rate because a handful of pilots get themselves into a mindset
where they are willing to enter conditions they would have not entered
without the big round "insurance policy". Often they get away with pushing
things. Sometimes they don't, and those accidents are the ones that are
taking the Cirrus accident rate to higher than predicted levels.

The problem is with the pilots, not the airplanes.

I agree.

This discussion has come up at least twice a year since the SR-20 and
22 came out.

The SR-22 is a capable airplane. It has the BRS for "just in case", it
has the weeping wing deice for "just in case". It's not for know
icing, but just in case, it has the simple (er) set of engine and prop
controls, and it has fixed gear. BUT it has high wing loading. A
fair amount higher than most fixed gear pilots are used to and
noticeable heavier than a Bo. SR-22 loading is about 23.5 while the Bo
is on the order as about the same as a Cherokee at 17.2. The Bo wing
loading covers a wide rage from about 16 to 19# per sq ft. It's one
whale of a lot slipperier though than the Cherokee though.
This is almost 32% heavier loading compared to the Cherokee and the
lighter Bonanzas and Debonairs. That is not to be taken lightly and
there is no pun intended. Over a 30% change in wing loading is a
serious change particularly for low time pilots.

I thought I'd take the easy way out and do a quick search instead of
calculating a bunch of wing loadings. The first thing that came up
was: http://www.aviation-pilots.com/construct/thread41.html
Then I noted who did the calculations. Careful what you say as it's
sometimes surprising as to where it shows up. :-))

At any rate, the SR-22 has all these whiz bang safety features AND
it's fixed gear, but it has the performance of a Bonanza with up to
30% heavier wing loading. The safety features are great, but here we
have an airplane that is meant for, or should be meant for experienced
pilots used to high performance be it fixed or retract gear.

Put all these features in a plane and then put the typical pilot with
a fixed gear mentality behind the yoke and it could be a recipe for
disaster. I mean no disrespect to fixed gear pilots. The typical fixed
gear pilot moving to the SR-22 would be akin to me moving to a TBM-700
or 850 One is a pilot with a 130 MPH mind moving to a 200 MPH airplane
while I'd be the pilot with a 200 MPH mind moving to a 360 MPH
airplane. OTOH I do have at least a little experience with faster
planes with much higher wing loading, but not enough to be safe
though.

My point is that even with all the training provided and *required*
the pilots *appear* "to me" to be flying a 200 MPH high performance
airplane as if it were a 130 MPH airplane. As a purely personal
opinion, I think they should forget it has a fixed gear and fly it as
if it were a retract.

Actually I think the retract has an advantage. The SR-22 is slippery
with a high wing loading. In a Bonanza if you get into trouble they
tell you to put the gear down and forget the doors. When the gear goes
down even at pattern speed it feels like some one put the brakes on
although the brakes with those tires don't have that much authority on
the runway. :-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

In article ,
"Roger (K8RI)" wrote:

In a Bonanza if you get into trouble they
tell you to put the gear down and forget the doors. When the gear goes
down even at pattern speed it feels like some one put the brakes on
although the brakes with those tires don't have that much authority on
the runway. :-))

The best way to slow a retract down is to put the gear down in the air, and
pick it up again in the flare. :-)