But in trying to determine what the differences are between the Diamond DA40 and the Cirrus SR20, I came across some interesting material, starting with this marketing brochure from Cirrus comparing the specs, features, and costs of the two (gosh, can you imagine which came out looking like the better deal?):
http://www.whycirrus.com/compare/pdf/cirrus-vs-diamond-da40-xls.pdf
Wow... That is so far off it's not funny.
First, there's the blatant falsehoods:
* 75% cruise performance of 137 KTAS - I get 139-140 on less than 75%, on an older, slower, non-XLS bird.
* 700 fpm sea-level climb and 450 fpm at 6,000 feet: Right out of the performance tables in the POH, sea-level climb is 900 fpm and at 6,000 feet it's 600 fpm. Yes, that's at gross weight, and based on my experiences so far, maybe even a little conservative.
* 10.7 gph at 6,000 feet? Only if you're running awfully rich. I get more like 8.5 gph at 6,000.
* 12.8 nmpg - Hmmm. 8.5 gph and 140 knots is 16.47 nmpg.
* Dual alternators not available? Wrong again. And on the Diamond, the 2nd alternator comes with air conditioning, too.
* "Robust/Fault-tolerant electrical system" not available? Funny, I have more backups on the DA40 than a Cirrus does, with easy load-shedding via the Essential Bus, and the completely isolated oh-**** backup Emergency switch & batteries too.
* Separate baggage door not available? Well, I guess technically you could say that and consider it the truth, since Diamond's separate baggage door can be used to load people, but come ON.
And then, there's the stuff that's misleading at best:
* Front seats not adjustable - Well gee Cirrus, your rudders aren't adjustable either!
* 56 gallons vs. 50 gallons usable fuel. Hmmm, I see that they don't point out the difference in fuel burn at all...
Of course, I don't expect Cirrus to actually tell the whole truth in a comparison between the SR20 and the DA40XLS - They'd probably never sell another SR20. Not that it's a bad plane - But the DA40 is better.
Diamond claims either 0.16 (text) or 0.208 (chart) fatal accidents per 100,000 flight hours. (A more useful metric than accidents per fleet size.) By comparison, they claim the average GA fatal accident rate is 1.27 per 100,000 hours.
The problem with all of the "per 100,000 hours" statistics is that it's a guess. Nobody really knows how many hours each type is flying. I think my comparison of TTAF's is about as close as you can get to reality.
All Diamond Single Engine (SE) planes are claimed to have twice as many accidents (fatal and non-fatal) per 100,000 hours than Cirrus!
Shocking.
Again, it's a guess.
"About half of the fatal accident pilots had less than 150 hours of experience in an SR2X. Two fatal Cirrus accidents occurred during training, one during transition training and the other during primary training of an experienced helicopter pilot."
True of pretty much any type. Time in type is one of the most reliable indicators of pilot safety, and that's why your insurance cost goes down significantly once you have a reasonable amount of time in type.
- Poor weather decision making:
"Weather is a huge factor in Cirrus accidents [...] Two-thirds of Cirrus fatal accidents involve bad weather (IMC), including low ceilings, fog, icing and thunderstorms."
Probably a huge factor in all accidents, unfortunately - Though I have no doubt that Cirrus is probably higher than average because they market their planes and train their pilots in a way that would tend to make them feel invincible, IMHO.
"My estimation is that 30% of the fatal accidents had a high probability of success if the pilot had pulled the CAPS handle; overall 23 of 41, or 56%, had a high-to-middle level probability of success"
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I would agree that there are a lot of situations where CAPS would have saved the day - but the red handle didn't get pulled. (There are a number of NTSB reports that state that the locking pin was not removed from the red handle - Which is pretty much item #1 on the Cirrus preflight checklist. The chute's pretty useless if you can't pull it when the time comes.
)
The problem is, it seems that people allow themselves to get INTO a situation that would require the chute by using the chute as one of their outs in their preflight decisionmaking. Then, when it comes time to pull the chute, they realize how stupid of a decision that was, and they don't pull it, they try to save the plane when it's already too late. I think there's other psychological factors involved as well - For example, to pull the red handle, you first need to admit to yourself that you're no longer in control. That's a very difficult thing for a lot of pilots.
My post's style was semantically equivalent to beginning it with "Hypothetically, if...." (I had actually considered writing it that way.)
Probably a good idea for you to try that next time, so you're not misunderstood.
If I had made it up I wouldn't have said in the same post it was a hypothetical in order to demonstrate the possible erroneous assumption you were making!
If you think I'm making an erroneous assumption, best to prove it with real data instead of made-up data.
By the way - nice research on the TTAF values from online used-aircraft listings. Very clever. The only thing I could think of prior to seeing your post was to somehow record the Hobbs hours of a random sample of aircraft by physically going to them. But in any case, you've made a good case to me with plausible statistics.
Thanks - I think that's probably about as good as we'll get with these stats, unless the FAA starts requiring A&P/IA's to send them each airplane's TTAF each year after the annual.
Yes, Diamond does seem to have a much lower fatal accident rate. But WHY?
That's a question that nobody can definitively answer. But, there are a multitude of possible answers:
1) Diamond doesn't sell their airplanes as being the ultimate transportation solution - Result: It's easier for a Diamond pilot to stay on the ground on a bad-weather day, since they don't have the expectation that "the plane will get me there."
2) Diamond doesn't have a chute. Yeah, this should not adversely affect safety, but it sure seems to. Some of the Cirrus accident reports are just mind-blowing when it comes to reliance on the chute.
3) More forgiving. Diamond has a long wing with a high aspect ratio that results in excellent glide characteristics, and stalls slower. That means less energy to dissipate in an accident. Also, the Diamond's tail surfaces are much larger, and the handling qualities are excellent. It's a really nice-flying airplane.
3a) Since it's such a nice-flying airplane, Diamond pilots might be more likely to do more hand-flying, keeping them more proficient for when the gadgets fail.
4) Once you've gotten yourself in a crash - Diamonds don't burn (see aforementioned discussion of the tank design). Cirruses do. I think that's a LARGE part of the high incidence of fatal accidents with respect to total accidents on the Cirruses.
Other than that, the two airplanes really have a lot in common, so it's hard to come up with other reasons why there is such a disparity in the safety record.
It's a VERY user-friendly airplane. 
who state that they absolutely know a certain aircraft is unsafe (ie. SR22) or a certain type (i.e. experimental) are just blowing so much wind (with all due rerspect). 