Accident Database / Post Crash Fires / How many flying?
Posted: Wed Nov 10, 2021 10:12 pm
by GraemeSmith
The “Fatal in Florida” that I noted earlier in the week included a post-crash fire. This sorta jogged my brain a bit as I was under the impression that there have been a few fires caused by the under glareshield fuel tanks moving after a crash. Indeed, in my legacy Sonex I have modified the fuel line from the tank to the firewall to make it flexible so that it might avoid a rigid line tearing the tank fitting out the tank if the firewall deformed in a crash.
And it just so happened that the FAA WINGS Safety Manager at the Boston FSDO mentioned the Florida crash and also commented on the post-crash fire. He was under the same impression as me.
So - how prevalent are they?
Well the new NTSB database it much easier to search and sort - so I started there. I also then pulled the FAA database of currently registered and DE-registered aircraft (presumably accident aircraft) to get a sense of just how many Sonex Aircraft (all types) are out there flying and what is our accident rate REALLY? As a percentage of all aircraft completed and flying. So in summary:
Current Registry
502 Aircraft in Total
“AeroVee” - 1 (that’s what is says the aircraft type is!)
Onex - 82
Sonex - 289
Sonex B - 7
Sub-Sonex - 15
Waiex - 79
Waiex B - 5
Xenos - 24
Deregistered
87 Aircraft in Total
Exports
Australia - 3 Waiex, Waiex, Waiex
Canada - 4 Sonex, Sonex, Sonex, Waiex
France - 1 Sonex
Thailand - 1 Sonex
Deregistered still in USA
Onex - 4
Sonex - 62
Waiex - 10
Xenos - 2
Source of above - FAA Releasable Aircraft Data from Registration Database 10 Oct 2021
NOTE 1 - This does not necessarily represent aircraft flying. Aircraft that are close to flying but have not yet flown, but are registered appear in the figures above.
NOTE 2 - Aircraft that have been in recent accidents and that were destroyed - may still appear to be registered. The Sub-Sonex that recently went in a lake is an example of this. It only appears in a preliminary NTSB report and is still in the registry - though destroyed.
NOTE 3 - None the less there is a broad correlation between the 78 deregistered aircraft and the 60 reports in the NTSB database.
In the NTSB Database of Investigations
60 Reports (see attached summary in a spreadsheet - in attached ZIP file)
Investigating post-crash fires
Reading all 60 reports and dockets that were available in the NTSB Database (not all are) there were 3 post-crash fires that consumed the aircraft. 2 were almost certainly NOT survivable as the fire was after a blunt force stall spin impact. One was after a level forced landing but there was not sufficient information to determine if the pilot might have survived if there had not been a fire.
2 fires were in flight. One electrical in nature and the second was a fuel fire caused by improper assembly of the fuel lines from the tank to the firewall. The pilot survived that fire.
NOTE 1 - The Sonex crash and burn in Florida 8 NOV 2021 is an additional post-crash fire that has not yet appeared in the NTSB database.
NOTE 2 - While I didn’t tabulate the 60 crashes - a very large number had an accident chain that ran: Distraction caused by engine problem/failure followed by loss of control/stall spin or loss of control/while attempting to land on whatever was available. Long and the short - don’t get distracted - keep the plane flying. AVIATE first!
NOTE 3 - One investigation of a fatal crash had absolutely no probable cause even speculated as “aircraft was not recovered from the swamp”.
–
So if you take 502 registered and 87 deregistered. There are 589 US completions or NEAR completions of Sonex Aircraft (all models). Based on a “guestimate” that at least 50 of the registered aircraft are not actually flying. (This a rough inspection of the list and recognizing folks I know are not flying yet and are still building). So let’s call it 540 flying or used to fly. 60 made NTSB reports.
That’s an accident rate of ~ 11.1% of aircraft built and flown
The fatal rate (20 people in 18 accidents) - 3.4% of aircraft built and flown
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 12:03 am
by pilotyoung
Thanks for doing the research and posting about it. That is a valuable to all of us Sonex owners.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 7:16 am
by kmacht
Sobering numbers. If accurate it would say you have about a 1 in 10 chance of getting into an accident in your Sonex and a 1 in 30 chance of dying in it. Those are horrible odds.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 10:19 am
by pfhoeycfi
Great information. One of my early mentors told me that perhaps the best step I could take to protect against loss of control scenarios and prepare for loss of power situations was to get my glider rating and some XC experience. I have no idea if there is any hard data that would suggest he is right…but he did have 40k GA hours. Personally, the training and experience that I have had in gliders is by far the most valuable that I have had.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 10:44 am
by radfordc
Hard to say if the Sonex fares worst than other similar Experimental planes? Here is a good article discussing the overall fatal accident picture: https://www.avweb.com/flight-safety/ris … l-factors/
Key points
- Pilot miscontrol—errors made in the control or guidance of the aircraft—is the major cause of homebuilt accidents regardless of injury severity.
- Pilot judgment issues. Nearly a quarter of the cases involve a deliberate decision by the pilot—mostly unnecessary low flying or continued VFR into IFR.
- Fatal Accident Rate-about a quarter of homebuilt accidents result in fatalities. The overall GA rate is about 18%
- What drives whether an accident results in a fatality? Two things: aircraft’s speed at impact. and ability of the structure to protect the occupants
Another article addressing fire: https://www.kitplanes.com/homebuilt-accidents-fire/
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 10:47 am
by WesRagle
Hi Guys,
Yes it is sobering. I haven’t learned to use the new data base interface yet but I did go through this a while back with the old interface, just scribbling down numbers, and came up with a similar result.
It begs the question: Why?
- Pilot proficiency/training?
- Airframe flight characteristics?
- Firewall Forward?
- Attitude/mindset of Sonex pilots?
I don’t know, but I’m very suspicious of number 3. The recent accident in Burleson (south Ft. Worth) struck close to home (https://sonexbuilders.net/viewtopic.php?f=25&t=6019&p=45324&hilit=burleson#p45324).
If you compare the Sonex models with the RV-9A, I believe the RV-9 fatality rates are about 1/3 that of the Sonex models.
It’s troubling.
Wes
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 11:15 am
by Scott Todd
But I don’t think we should let the 1in10 or 1in30 number scare us out of one. There are a couple things to look at. First its a small sample size. If the size were two, the 1in2 chance looks REALLY bad. As the sample grows, 1in3, 1in4, etc, it still looks really bad. Granted 1in10 IS bad as kmacht points out but it should decline as the sample size grows. There is also an infant mortality thing at play here which kind of leads to the second thing to look at.
The Sonex line of airplanes are not trainers. My apologies to the company but it really isn’t. Its quick on the controls, has a moderate wing loading, many are built as tail draggers, and they use non certified engines. Any one of these factors contributes to accident causes. I think stall/spin is the leading cause which comes back to moderate wing loading and quick controls. Its just NOT a Cessna or Piper.
I don’t want to discuss it here but non-certified engines statistically quit more that certified ones. They are usually assembled and maintained by non certified mechanics. This doesn’t mean some of them are not done well but statistically speaking…And when they quit, the leading cause of accidents/injury comes into play, stall spin.
Our beloved little airplanes are promoted as affordable with descent performance, which sells airplanes but our accident rate is high. Insurance companies are figuring this out and hence the difficulty we are having. But notice the trend of highly experienced pilots with lots of Sonex time still getting affordable insurance. We need to continue to promote safety and training. Thank you Graeme for putting this together.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 11:45 am
by radfordc
pfhoeycfi wrote:One of my early mentors told me that perhaps the best step I could take to protect against loss of control scenarios and prepare for loss of power situations was to get my glider rating
I believe that having actual practice landing without an engine is a big advantage when the rubber band breaks.
I started in ultralights and engine failures were not uncommon (5 or 6 for me over 10 years). For practice I would routinely shut down the engine in flight and land deadstick…just like gliders do every flight. I didn’t ever shut down a Sonex on purpose but did once have an engine stoppage on a test flight and landed with no problem. In a Sonex, pulling the throttle to idle and executing the landing to a full stop touchdown is good practice.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 1:19 pm
by pilotyoung
I have two points to add. First, listen and read Dan Gryder’s information. He recommends a speed, DMMS, Defined Minimum Maneuvering Speed. It is 1.404 times the clean stall speed. He recommends putting it on your airspeed indicator with red tape. I have it on my Onex, it is 65 mph. Then he says no matter what happens, don’t go below this speed until you are on final and therefore have no more turns. This practice will keep you from doing a stall/spin. There are times when I am turning from downwind to base or base to final and it see I am heading below 65, DMMS, and I immediately correct. With it on the airspeed indicator in red, you can’t forget it.
Second, my insurance broker told me that the main reason it is so expensive to insure a Sonex product is that there is no factory training program available. In reality, there is no training program at all. If Sonex would restart its training program, it would help us all buy insurance at a more reasonable rate and it might save some lives. Or alternatively is Sonex would partner with someone to start and run a training program it would be a big benefit to Sonex owners. And it would only take one airplane, a Sonex or Waiex tailwheel. With the exception of a Sub-Sonex, I think the insurance companies would accept dual instruction in a Sonex or Waiex tailwheel for the nosewheel airplanes and the Onex.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 1:33 pm
by GraemeSmith
Scott Todd wrote:But I don’t think we should let the 1in10 or 1in30 number scare us out of one. There are a couple things to look at. First its a small sample size. If the size were two, the 1in2 chance looks REALLY bad. As the sample grows, 1in3, 1in4, etc, it still looks really bad. Granted 1in10 IS bad as kmacht points out but it should decline as the sample size grows. There is also an infant mortality thing at play here which kind of leads to the second thing to look at.
Well one thing folks should NOT read into this is that you have a 1 in 10 chance of having an accident every time you fly. This is about how well the fleet fares.
Infant mortality is a factor. But you could only get a comparison if you could compare to the same number of (different type of) aircraft in about the same time period to see who fared worse. To take it to it’s extreme:
The longer you leave a fleet in being - the worse the fleet figure will get. I mean they built about 23,000 C150/2’s starting 50 years ago. Keep it up for long enough and their figures will look horrible as a percentage of losses against aircraft built. I think there are about 8,000 left on US registry. And of course many just rotted away or were exported. That said the current accident attrition rate on C150/2’s in the USA is about 2 a week.
–
If you read the narratives of probable cause in the spreadsheet - people are just not staying in control of the planes once distracted.
There are also a few - first flight and fatal. Let’s face it - jumping into a plane it took you 4 years to build and short on any recent currency because you have been busy building is not a good thing.
–
Interesting point about the insurance broker. I got some traction with offering to do the Foundation transition training syllabus as part of my first 5 hours with a CFI (down from 10 with no syllabus). Once we had that out the way - the CFI and I spent a lot of time doing improbable turns at maximum gross at ever lower altitudes over a very quiet and large airport. Minimum Maneuvering Speed established at 60knots Indicated at 45-degree bank.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 3:02 pm
by GordonTurner
Hi Graeme
Many of the Corvair powered airplanes go by “Cleanex” or some derivative of that. Can you add that to your search?
Gordon
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 5:33 pm
by GraemeSmith
GordonTurner wrote:Hi Graeme
Many of the Corvair powered airplanes go by “Cleanex” or some derivative of that. Can you add that to your search?
Gordon
No joy. I found the most reliable way of bubbling up aircraft was to use the search term “Sonex” in the "Kit Manufacturer field of the FAA database. Any which way I sliced that got me the maximum number of results.
If you have the N number of a Cleanex - then I can look and see how it is portrayed in the database and see if I already got it - or if it gives me something new to look for.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 7:17 pm
by daleandee
GordonTurner wrote:Many of the Corvair powered airplanes go by “Cleanex” or some derivative of that. Can you add that to your search?
FWIW … as a Cleanex owner I try to keep close tabs on Corvair powered aircraft (of any kind) that have incidents or accidents. As it relates to this thread I’m only aware of a single non-fatal accident that seems to have a reasonable explanation as to the cause:
http://www.kathrynsreport.com/2019/02/s … il-22.html
I discussed this accident in my thread titled “Corvair Engines - The Justification Series” and also referenced two important points that the NTSB report (at that time) noted were the causes of accidents for experimental airplanes. Here is the text from that thread from the NTSB report:
• Accident analyses indicate that power plant failures and loss of control in flight are the most common E-AB aircraft accident occurrences by a large margin and that accident occurrences are similar for both new and used aircraft.
• Structural failures have not been a common occurrence among E-AB aircraft.
The entire thread is found here: viewtopic.php?f=9&t=4273&hilit=justification
Hope this helps …
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 7:26 pm
by WesRagle
Hey Dale,
Don’t forget this one.
https://sonexbuilders.net/viewtopic.php?f=21&t=5637&p=42654&hilit=clay#p42649
Wes
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Thu Nov 11, 2021 8:22 pm
by GraemeSmith
So here it is with Engine Types added in. I had to go trawl the FAA Database and NTSB Final Reports to put this together.
The new data is in the cream colored columns and is as worded from the source data - so you have to do a little interpretation. But basically 18 Jabs, a Viking, a Corvair and the rest are VW based. Ignore 2 turbines on the Sub-Sonex.
Now just because an engine appears in a report - does not mean it was the cause. When someone taxis into you and chops the tail off your Sonex - you appear in the report - but the engine has nothing to do with it. Same for a Waiex structural tail failure in flight - poor build quality on what turned out to be a marginal design. Pilot ground loops the take off - nothing to do with the engine - well not directly. Another - an alcohol imparied pilot.
So read in conjunction with the probable cause narrative line.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Fri Nov 12, 2021 3:13 pm
by GraemeSmith
So this commentary is from Steve Brown who is the FAA Safety Manager at the Boston FSDO. I am a VOLUNTEER safety rep for the FAA. I can’t speak for them or say anything authoritative on behalf of the FAA - but I give talks for WINGS credits sometimes. I was sharing my work with him to try and get some greater context - as he has a “bigger view” of all types of EAB. Steve is a “good guy”. On the side of GA. He wants to make things safer too. This comment from him and graph are published with his explicit permission:
As always, interesting. That is a large percentage of the fleet.
Looking at your spreadsheet there was something that caught my attention. The Rate of Fatal Accidents. I know it and all Experimental aircraft tend to have a higher rate of Fatal Accidents, but just looking at the data it seemed high.
Here is a comparison of a chart from your spreadsheet data and the NALL report data. It appears that about 1 in 3 accidents in a Sonex are fatal, where in all other experimental it is about 1 in 4 or 5.
You know what would probably be scarier – is the rate per # hours flown. Would be hard to get the data, but I bet the hours are low and the rate per 100,000 hours is high. That is something in the glider world that many people have a hard time comprehending. There the Fatal Accident rate is about the same as the overall fixed wing accident rate, with the overall glider accident rate being about 4 times high. I bet you would see at least the same in the Sonex world.
I looked quickly at the trends with the engine type on accident severity, but nothing was really jumping out at me.
Boy – there are a lot of engine issues, loss of power, especially in the Fatal and Serious Accidents. A top Priority on pilot skills would be “dead Stick” landings. The structure is not that massive/energy absorbing, if you are going to hit something, you need to do it as slow as possible and in control as much as possible. You need to be prepared for engine failure.
Now, that being said, more of a root cause is the engine assembly/maintenance of the engine and components. There are a lot of failures for reasons that should not be there. That is where I would put the focus to reduce the accident rate overall. Reduce the Fatal and Serious accident by strong emphasis on engine out procedures, off airport landings and as Bob Hoover said, “Fly it as far into the crash as you can”.
Thanx
SKB
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Sat Nov 13, 2021 11:13 am
by BRS
Thanks Graeme,
Steve’s admonition of engine-out and dead-stick proficiency is well taken. Once again the need for training is underscored and the lack of availability is highlighted.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Sat Nov 13, 2021 2:39 pm
by radfordc
If deadstick, off-airport landing skills are needed (and it is evident they are) what is the best way to acquire those skills? Is the typical Flight Review procedure enough (CFI says “you have an engine failure” and pulls throttle to idle, student looks for a landing field and sets up an approach. On final the power goes back in and climb out ensues). What’s missing here is the “startle factor” that comes from knowing the engine just quit for real; the problem of multi-tasking: trying to get the engine restarted, looking for a landing spot, making emergency radio calls, and last (but not least) flying the plane. I do know from my own experience that experiencing an actual engine failure is mentally much different than just doing a practice approach at idle power.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Sat Nov 13, 2021 3:36 pm
by pfhoeycfi
There are great articles in AOPA, EAA, Flying and from the FAA on how to best perform the power off 180 deg approach and landing and its actually a good exercise to do on towing days where I’m making 15… 20 …30 landings.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Sat Nov 13, 2021 6:59 pm
by GraemeSmith
radfordc wrote:If deadstick, off-airport landing skills are needed (and it is evident they are) what is the best way to acquire those skills? Is the typical Flight Review procedure enough (CFI says “you have an engine failure” and pulls throttle to idle, student looks for a landing field and sets up an approach. On final the power goes back in and climb out ensues). What’s missing here is the “startle factor” that comes from knowing the engine just quit for real; the problem of multi-tasking: trying to get the engine restarted, looking for a landing spot, making emergency radio calls, and last (but not least) flying the plane. I do know from my own experience that experiencing an actual engine failure is mentally much different than just doing a practice approach at idle power.
I put my survival from a real engine out (non Sonex) over mountains and over the top VFR down to practice, practice, practice. You revert to training in crisis. You are terrible at making it up on the spur of the moment. So when the engine quit - I was - Establish Vg, NRST - DIRECT - MAYDAY call and settled down to try and pull off a 12 mile glide to a runway with just altitude for 10 miles in the glide tank. I made it with 1,000ft to spare and had to slip her in hard. Because I trained for it.
–
I practice all my airwork and drills REGULARLY. Just these last three flights I’ve been doing long glide engine outs. First two - WAY too high, had to spiral off altitude on final and STILL was way too high if I’d been landing it for real. Took till today to nail it and have energy to roll in and get off the runway.
–
Big letters on the panel - “Minimum Maneuvering Speed - 60 KIAS at 45 degrees”. Practice, practice, practice don’t break it and you should avoid “stall spin”.
Accident Database / Post Crash Fires / How many flying?
Posted: Mon Nov 15, 2021 9:07 am
by Gmoney
So what do we do as owner/builders?
Do we crowd fund a training facility?
Do we develop a syllabus?
Do we find a CFI that is willing and able to provide that training?
Do we look at accidents, determine root cause and determine a refresh for incident?
If it is motor related do we look at root cause, make recommendations?
I/we would a agree Sonex makes a good product or we would not make the time and money decisions to own and build.
I guess the real question is what can I do to make a better Sonex community? Can we say we own and operate the safest home built available? What is it going to take to turn that data around?
Gary
Sent from my iPhone using Tapatalk
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Mon Nov 15, 2021 11:06 am
by GraemeSmith
I would say “standby” on that. Peoole who have done my hours survey have been candid about some issues. There are some clear trends - though nothing earthshatteringly new. I’ll be crunching the numbers again this weekend.
There IS a syllabus - see the Foundation web site.
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Mon Nov 22, 2021 9:56 am
by GraemeSmith
Still Crunching. Lot of data to corral and to align with FAA and NTSB methods so I can make meaningful comparisons.
Accident Database / Post Crash Fires / How many flying?
Posted: Fri Nov 26, 2021 10:19 am
by Gmoney
GraemeSmith wrote:I would say “standby” on that. Peoole who have done my hours survey have been candid about some issues. There are some clear trends - though nothing earthshatteringly new. I’ll be crunching the numbers again this weekend.
There IS a syllabus - see the Foundation web site.
Wow, definitely worth the wait. Nice to see what the groups focus is on the provided data.
Thank you for taking the time to gather and sort the data.
Gary
Sent from my iPhone using Tapatalk
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Fri Nov 26, 2021 1:08 pm
by NWade
radfordc wrote:If deadstick, off-airport landing skills are needed (and it is evident they are) what is the best way to acquire those skills?
Here’s a great way you can get a lot of “dead-stick” practice: find a nearby glider club/operation, join for a season, and at least get to the point where you Solo.
Glider training involves a lot of the following:
- Practice landings with an “engine-out” - teaching you how to estimate your glide range, approach angle, and making maneuvers in order to safely hit your desired touchdown point.
- Using slips to alter your glide-path on final approach - in gliders this is in case our spoilers malfunction; but its great for powered flying when you need to make a short approach or alter your glide-path without slowing up the airplane in an engine-out scenario.
- Rope-breaks during the tow - this gives you the “startle factor” of a failure on climb-out and trains you to lower the nose, establish good glide speed, assess your chances to return to the airfield, and maneuver for that landing.
There’s more to flying gliders/sailplanes, but just getting to solo will add a lot more skill to your everyday Sonex flying!
NOTE: If possible, train at a glider club/operation that does not use 1950’s Schweizer gliders (as they fly like box-kites and require giant control inputs; very different from other gliders and from a Sonex). Places that offer training in Blanik gliders, Grob gliders, or ASK gliders will feel a lot more like “normal” airplanes (as well as flying like modern gliders).
Finally, please do not hesitate to message me if you want to know more, or give this a try! I love helping folks get into gliding/soaring, I help organize mentorship events and competitions in the US each year, and I know many of the clubs and commercial operations around the US (as well as a few in the UK, France, and NZ).
–Noel
Sonex #1339
ASG-29
Re: Accident Database / Post Crash Fires / How many flying?
Posted: Fri Nov 26, 2021 2:28 pm
by radfordc
NWade wrote:
[*] Using slips to alter your glide-path on final approach - in gliders this is in case our spoilers malfunction; but its great for powered flying when you need to make a short approach or alter your glide-path without slowing up the airplane in an engine-out scenario.
This works well in a Sonex. I did a test flight once that ended with a deadstick landing. A strong slip got it down with no danger of undershooting the runway. https://youtu.be/45khkO4hvnY