Cirrus crash near Grand Canyon

[gil_mor]

http://www.inquisitr.com/131097/grand-canyon-plane-crash-2011/

 

[Jim Logajan]

No one's "picking on" poor little Cirrus by saying a large number of them are consumed by post-crash fires.

I just spent over an hour examining 20 fatal accidents from 2002 to 2006 in the NTSB database that involved Cirrus airplanes. (I skipped any without probable causes, 2 that went into water, and the Cory Liddle accident.) There was no post-impact fire in 12 of the 20 accidents. So 40% of my sample had post-impact fires that destroyed much of the airframe. I can post my samples here or on another thread.

I would have to also examine fatal accidents from some other make and model to act as "control". Any suggestions? (I can only find 10 Diamond model 20 and 40 accidents involving fatalities in the NTSB database, which I think is perhaps too low to use for determining even an rough average.) I presume another composite aircraft using a different fuel tank would be appropriate. Statistics for a metal airplane might be worth estimating as another comparison.

 

[Jim Logajan]

I just spent over an hour examining 20 fatal accidents from 2002 to 2006 in the NTSB database that involved Cirrus airplanes. (I skipped any without probable causes, 2 that went into water, and the Cory Liddle accident.) There was no post-impact fire in 12 of the 20 accidents. So 40% of my sample had post-impact fires that destroyed much of the airframe. I can post my samples here or on another thread.

I would have to also examine fatal accidents from some other make and model to act as "control". Any suggestions? (I can only find 10 Diamond model 20 and 40 accidents involving fatalities in the NTSB database, which I think is perhaps too low to use for determining even an rough average.) I presume another composite aircraft using a different fuel tank would be appropriate. Statistics for a metal airplane might be worth estimating as another comparison.

I decided to look at the Diamond DA20 and DA40 NTSB accident resports. There were only 6 fatal accidents with NTSB probable causes listed, and 2 of them involved crashes into water. Of the remaining 4, 1 was destroyed by post-impact fire. That small sample yields 25% destroyed by post-crash fires versus Cirrus aircraft. If preliminary reports are included in the Diamond assessment, only 3 have mentions of damage information. Of those 3, 1 was destroyed by fire. So 2 of all 7 accidents were destroyed by post-crash fires.

Alas, my Diamond sample size is too small. At face value, 29% of the Diamond aircraft were destroyed by fire versus 40% of Cirrus. However, if the next Diamond aircraft statistical sample is destroyed by fire but not the next Cirrus sample, then ~38% (3 of 8) of Diamond aircraft would have been destroyed by post-impact fires compared to ~38% (8 of 21) of Cirrus. A dead heat. Going the other way, the next samples could make it ~25% for Diamond and ~43% for Cirrus.

While a case can be made that Cirrus composite aircraft are more likely to burn on impact than, for example, Diamond composite aircraft, my admittedly crude analysis does not suggest a large difference.

 

[Jim Logajan]

If there is a reputation for post crash fires in a Cirrus, then I think it only matters if the fire created additional injuries. So I would think the data that matters is low-speed accidents such as landing accidents and controlled off field landings. I don't see why it matters if a plane spins into the ground at a high rate of speed whether or not there is a post-impact fire. It's a fatal accident no matter what.

However if an accident would have otherwise been survivable or fire resulted in more serious injuries, then it is very significant. Because of this, it would be interesting to look at the types of accidents that resulted in fires. I agree the sample size for Diamonds is too small. Also, a DA20 is a very different plane than a DA40 and so I'm not sure lumping the two together makes much sense. A DA40 is a closer comp to a Cirrus with similar performance to a SR20 and so I believe it would be more accurate to compare DA40 fires to those of Cirrus aircraft.

Since both Cirrus planes and DA40s claim high g crash resistant cabins and have airbags, the envelope of survivable crashes should be larger for these planes than similar GA aircraft. A greater risk of fire would obviously negate this.

I do not know if DA20 and DA40 fuel tanks are similar in construction (fire propensity and the difference in fuel tank construction between one of the Diamond models and Cirrus models has been brought up in other threads.) I was assuming they were. I also assumed any other differences between the two models would not significantly alter their propensity to burn. These assumptions may of course be grossly incorrect.

As best I could determine, precisely zero of the Cirrus and Diamond crashes in my samples yielded deaths due to fires. (I did not review all the Cirrus crashes; I did my equivalent of a random sampling since I don't have that kind of time to invest. There may be some Cirrus fatalities due to fire. If there are, it is probably under 5%.)

Since ~60% of the Cirrus accidents I reviewed didn't burn even when they crashed hard enough to produce fatalities, it seems unlikely there is any propensity for Pinto-like behavior yielding a lot of injuries due to fires started in non-fatal crashes.

However, I'm a third party (who has never seen a Cirrus in real life) just trying to add some insight based on the facts that have been recorded elsewhere. It should be up to those hinting or implying an assertion is true to provide some factual justification for said assertions. Or those curious (as I was.) Anything beyond that is up to someone else.

At this point I do not see anything to support the repeated (and subjectively annoying) assertion that Cirrus aircraft are significantly more prone to fires than other composite aircraft due, for example, to differences in fuel tank construction.