HSLD

I was just playing around with Data visualization this morning and created a quick chart. Nothing earth shattering, just another way to view the data.

Workbook: General Aviation Accidents 2012

Cubdriver

I make charts too, amazing what you can learn. Here's one using NTSB data- looks like the Cessna 320s & 411 might not be safest light twins.

SuperPilotJesse

This chart means nothing to the safety of those Cessna models...

If they are that much more popular then more accidents will seem to happen with that model.

If there are 10,000 C320s and 1,000 B58s and on average there is a 1% crash rate then its 100 and 10. So of course the 320 is going to have the larger percentage.... even if it were safer and it only had a .5% rate = 50, it would still be a bigger chunk of the fatalities, even though the rate is half the average...

I know I'm rambling, but I'm just saying.

HSLD

The chart only shows the distribution of general aviation accidents, there's no mention or inference of inherent safety of one make/model over the other.
With respect to Cessna, more Cessna aircraft have been involved in GA fatal accidents YTD than any other.

I agree with you that a relevant claim to inherent safety cannot be made with this data. Cheers.

Cubdriver

Jesse, you are correct that data interpretation is crucial with any data or chart presentation. The chart I posted shows the percentage of the total production number of a particular model crashed in a fatal way (obviously most crashes are fatal). For example, there were 301 units of Cessna 411 made, 36 of them crashed, that's 12%. It is not a statistic telling the likelihood of getting killed in a Cessna 411 really, although it hints that your safety is definitely less in that model than one which has never crashed (a few exist).

For example, let's say there is a model with a 100% fatal hull loss figure. That's a percentage, not a rate. It means that all those airplanes crashed and there are none of them left. Not a very successful airplane. However, that same airplane could have carried thousands of people for tens of years before they all eventually crashed. A more meaningful chart therefore might show the number of operating hours per fatality, or the number of safe operating hours per crash, or the number of fatalities of a model used in a particular type of operation (ie. Alaska Part 135).

The problem with that study is there is no data to base it on. What my charts shows is that given an aircraft exists, this % of the fleet crashed. I think it does tell us how safe those models are in some sense, and in point-of-fact the FAA suspended the 411 type certificate at one point due to numerous incidents.

Cessna 411 wiki

rickair7777

Concorde went from having the best all-time safety record in airline history to having the worst in two minutes.

320's might not be inherently dangerous, they might just be used for riskier missions.

No duchesses have ever crashed?

wizepilot

The C-320 was basically a longer version of the 310. But there was a hell of a lot less manufactured than the 310. So I think those numbers, as discussed, may be a bit slewed. Have time in both.

Cubdriver

A query of the NTSB data base shows 4 were lost out of 437 that were manufactured. It does not show up on my chart for some reason although it would show 0.9%.

CE-310: 6321 made, 346 crashed => 5.5% lost
CE-320: 580 made, 73 crashed => 12.6% lost

Again, a more meaningful understanding could be had from a study of fatal hull losses per operating hour, if only the data were available.

My reading in the subject tells me regardless of model, the highest loss rate in light twins occurs when a design has poor single engine climb performance. Any airplane that has poor SE climb performance is likely to lead to a fatal crash when the critical engine fails. This is especially true of twins that are both underpowered and use non-counter rotating props.