Re: Stall/spin accidents in our community
Posted: Fri Mar 03, 2017 11:03 am
Talking about stall/spins here helps raise awareness but I don't think it is asking the underlying question. Why are they stalling/spinning in in the first place? It is pretty rare for someone to stall/spin in a plane on a normal routine flight where nothing else goes wrong. Throw in an engine failure, airframe issues, distractions in the cockpit or doing something stupid like buzzing and the chance of it happening goes up significantly.
I just did a very unscientific look at the NTSB aviation accident database and am worried about what I see. Keep in mind that what is below is just a very broad look at some raw numbers without any analysis or vetting. If I or maybe someone else has some more time in the future it would be helpful to do some categorizing and sorting through the accidents to get a more accurate picture but here are the raw numbers. A search for Sonex/Waiex/Onex shows 39 accident listings. The sonex website shows 571 aircraft currently complete and flying. That gives an accident rate of around 6%. This means that 1 in 20 are getting into accidents of some sort.
I figured that maybe that is the going rate for homebuilts so I then looked at RV's. The RV 10 and 12 have the closest completion numbers to Sonex. The RV-12 has 496 completions with 6 accidents and the RV-10 has 821 completions with 12 accidents listed in the database. That gives a 1.2% and 1.4% accident rates or 1 in 75.
I'm positive those numbers when refined will change some but this post isn't about getting exact numbers. What I am more interested in is why the sonex line appears to have such a high accident rate and is there anything we can do to lower it.
It can't just be builder error as two factory aircraft are now included in those numbers. It isn't flight experience as the accidents have included both low time and very high time pilots. Other than the one Waiex with questionable build practices I don't think there have been any reported issues with the airframe. There has been lots of talk about engine issues, carb issues, etc on the forum so maybe there is something there. Could it be as simple as the Sonex product line taking off over the past few years and more aircraft are in or just out of the phase 1 flight tests where issues are most likely to crop up? Maybe it has something to do with how the plane stalls. Mine stalls so gently that it is easy to ignore it as you get close to the actual mush/break and I'm not sure I would recognize it in time if distracted while maneuvering low to the ground. Maybe it is something else that we haven't even discussed in the forums here yet.
I don't think the answer is going to be as easy as finding one single re-occurring cause in the statistics. If it was then it would have been fixed by now. What I think we need to do as a group is start looking for what can be done to make our flying safer. A few people have suggested LRI's which I initially thought I didn't need but after reading some of the posts here am reconsidering adding one to my plane. Maybe a dedicated forum section or thread to post up engine issues found while building or after flying for a while. Not a post asking for help but a post to just documenting things you have run into so others can see and learn from them. How about an annual condition inspection thread or forum? Post up what you have seen or found during your annual inspections. What works during the initial build may not be holding up after a year or two. Maybe a "never again" type section where people can post up anonymous things that people have experienced/done in their sonex that others could learn from.
I would urge the sonex foundation and other builders to think about what types of things can be done here to help improve the accident rate. The sonex product line has matured a lot since the early days of building from a set of plans and some bent channel. The actual building issues are far fewer than they were even 5 years ago. It is time to start focusing on how to support the flying fleet out there so they stay safe and reverse the reputation that the Sonex is starting to get outside of this forum.
Keith
#554
I just did a very unscientific look at the NTSB aviation accident database and am worried about what I see. Keep in mind that what is below is just a very broad look at some raw numbers without any analysis or vetting. If I or maybe someone else has some more time in the future it would be helpful to do some categorizing and sorting through the accidents to get a more accurate picture but here are the raw numbers. A search for Sonex/Waiex/Onex shows 39 accident listings. The sonex website shows 571 aircraft currently complete and flying. That gives an accident rate of around 6%. This means that 1 in 20 are getting into accidents of some sort.
I figured that maybe that is the going rate for homebuilts so I then looked at RV's. The RV 10 and 12 have the closest completion numbers to Sonex. The RV-12 has 496 completions with 6 accidents and the RV-10 has 821 completions with 12 accidents listed in the database. That gives a 1.2% and 1.4% accident rates or 1 in 75.
I'm positive those numbers when refined will change some but this post isn't about getting exact numbers. What I am more interested in is why the sonex line appears to have such a high accident rate and is there anything we can do to lower it.
It can't just be builder error as two factory aircraft are now included in those numbers. It isn't flight experience as the accidents have included both low time and very high time pilots. Other than the one Waiex with questionable build practices I don't think there have been any reported issues with the airframe. There has been lots of talk about engine issues, carb issues, etc on the forum so maybe there is something there. Could it be as simple as the Sonex product line taking off over the past few years and more aircraft are in or just out of the phase 1 flight tests where issues are most likely to crop up? Maybe it has something to do with how the plane stalls. Mine stalls so gently that it is easy to ignore it as you get close to the actual mush/break and I'm not sure I would recognize it in time if distracted while maneuvering low to the ground. Maybe it is something else that we haven't even discussed in the forums here yet.
I don't think the answer is going to be as easy as finding one single re-occurring cause in the statistics. If it was then it would have been fixed by now. What I think we need to do as a group is start looking for what can be done to make our flying safer. A few people have suggested LRI's which I initially thought I didn't need but after reading some of the posts here am reconsidering adding one to my plane. Maybe a dedicated forum section or thread to post up engine issues found while building or after flying for a while. Not a post asking for help but a post to just documenting things you have run into so others can see and learn from them. How about an annual condition inspection thread or forum? Post up what you have seen or found during your annual inspections. What works during the initial build may not be holding up after a year or two. Maybe a "never again" type section where people can post up anonymous things that people have experienced/done in their sonex that others could learn from.
I would urge the sonex foundation and other builders to think about what types of things can be done here to help improve the accident rate. The sonex product line has matured a lot since the early days of building from a set of plans and some bent channel. The actual building issues are far fewer than they were even 5 years ago. It is time to start focusing on how to support the flying fleet out there so they stay safe and reverse the reputation that the Sonex is starting to get outside of this forum.
Keith
#554