Stall/spin accidents in our community

General Safety and Training
1

Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 11:06 am

by WaiexN143NM

Hi all,
I believe we need to put more focus on this subject, in podcasts, (jeff, gary, john) and in the quarterly newsletter. Off the top of my head i can think of an accident in florida straight into the swamp, another one next to a airpark and pond. One in georgia on first long cross country after purchasing the aircraft, running out of fuel, and crashing at the airport. One in oshkosh. Now one into a condo roof in mass. There may be some more, id have to go look at the list of accidents. Some of these accidents had high time pilots(was currently flying airline ) , and some were low time, some still in phase one. The point is more effort needs to be expended individually, and as a group.
Does your plane have an AOA indicator or stall warning system.?If your plane doesnt have an efis with aoa then, id be installing something. And when its installed you need to go fly up high and do some slow flight and training. Pre stall and full stall. Get used to throttle settings, airspeeds, plane feel. Different flap settings.
If the one thing that can be taken away from the late great bob hoover, he always said to fly it completely thru the crash, then get out and say wow that was quite a ride.
Im not trying to diminish the tradgedy of anyone, or any incident. But we need to talk about this. Yesterdays accident just brought this to the spotlight again.
I looked at aircraft spruce they have many aoa systems, and stall warning devices. Take a look. If you dont have one, then think about installing something. And when the device is giving us info, then react, and FLY THE PLANE! No more stall spins. Please.
Feel free to add your thoughts.
WaiexN143NM
Michael

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 12:06 pm

by NWade

Thanks, Michael. I think this is an important conversation to return to every so-often (even when accidents are not happening).

Some additional suggestions for pilots to think about:

  • How low are my final approaches? Do I tend to fly a long flat glidepath that requires some throttle to carry (drag) it in?
  • How big/wide are my patterns?
  • How often do I practice medium-banked turns with an eye on my turn coordinator - especially at lower altitudes?
  • How often do I re-evaluate the terrain around my home airport and think about the various off-field landing options & consequences?
  • Do I think through a mental plan of action on every takeoff and before entering the landing pattern?
  • In addition to the wind speed & direction before each landing, do I stop and think about the wind gradient I may find on final approach? What about sources of turbulence near the ground as I descend in my pattern?

And its not enough to simply remember these items before each flight. In an emergency you aren’t going to have time to make up a plan - you need to have thought of one in advance. So take a couple of seconds to think through each subject and have a plan in mind. If you mentally rehearse it (or mumble it to yourself in the cockpit), then you will be able to react much more quickly and directly to the problem at-hand. Here’s an example in a crosswind takeoff situation: Between doing your run-up and taxiing onto the runway don’t just say “OK there’s a crosswind from the right”. Say to yourself “OK there’s a crosswind from the right and some trees on that side of the airport. So I’m likely to have some turbulence as I lift off. If I experience a problem on takeoff the wind will be drifting me over the hangars on the left so I’ll need to crab into the wind to land back on the runway. If I’m beyond the hangars and I turn left there’s an open field to land in but its downwind so I should expect a high groundspeed and not let the optics of that groundspeed fool me into stalling it early - watch the airspeed!”
This takes all of 5 seconds think / talk through. Isn’t better safety worth a few seconds of our time?

As a sailplane pilot, these are things we evaluate and practice a lot; but I think they’re things that are easy to forget or ignore or become complacent about in a powered aircraft. Its human nature to see something obvious and say “Oh yeah, I knew that!” But our brains are good at tricking us when it comes to the extent of our knowledge, because it blurs the line between what we recognize (i.e. a good idea on paper) and what we have internalized (i.e. what information we can dredge up from long-term memory on our own, without much prompting). Only items that we’ve internalized and can easily recall are useful to us in an urgent situation - if it isn’t automatic or innate information then we won’t think of it until after the stressful / high-pressure moment has passed. The best antidote is practice and to take the time to actually plot out our reactions in-advance, so that they’re readily available in short-term memory if we need them.

Fly Safe,

–Noel

P.S. As a sailplane pilot who’s set records and flown in national & international competition, I’m obviously a fan of soaring and I recommend glider training to any and all pilots. However, many clubs and operations in the US use the “Schweizer 2-33” glider that is terrible to fly (but they use it because its cheap). Also, many US clubs require you to spend all day at the airport just to get 1 or 2 short training flights in; which is fine if its your primary hobby or social group - but not so great if its not your main passion. So if you are interested in glider training for safety or to enhance your aviation knowledge, I highly recommend seeking out a commercial operation that can give you more flights in a shorter period of time (even though this costs more, its more effective training). I also strongly recommend trying to find a club or commercial operator where you can train in a more modern glider like a Schleicher, a Grob, or a Blanik. All of these are more “airplane-like” to fly than the 1937-designed Schweizers, which handle like a box-kite. :stuck_out_tongue:

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 1:12 pm

by LarryEWaiex121

Mike and Noel,

Just a quick observation here and it may not apply in this most recent accident but applies to many.
Look at the number one cause of these accidents leading up to a loss of control incident. The engine either quit outright or wasn’t producing enough power to remain airborne to the desired landing spot.
Quite simply, we need to reduce the engine failures by being hard nosed on the causes of these engine failures. It’s just unacceptable, the level of engine failures in homebuilt aircraft vs. store bought aircraft.
I’m not a big rules and regulations kind of guy but, this is one aspect of the “flexibility” of homebuilt airplanes that I disagree on completely. Airframe failures are a rarity, but not engine failures.
I think the FAA should mandate that a homebuilt airplanes fuel delivery system be built according to the plans purchased with the kit and be inspected as complying with the plans in its “initial” configuration. After phase 1 completion and the required hours flown off, it would then be feasible to allow experimentation by way of returning to phase 1 with the new system the builder wants to implement. I know this is an unpopular concept with many but, too many builders are incorporating pieces and ideas that clearly are not fully thought out or we wouldn’t be in this mess. They can’t allow themselves to follow the plans but feel confident to “re-engineer” the most critical part of the aircraft. No fuel for any reason means NO POWER!
In my mind two thing are happening here. One, with hours in type comes skill and understanding of how the aircraft handles. Two it proves the system works.
Too much is as risk as matters stand now. We have new builders with low time, or no time in type, flying a completely new airframe, engine, fuel system. Then they head off into the wild blue with probably an understanding of what can go wrong, but not the skills/mindset to deal with a full blown emergency. Its they’re baby and they don’t want to sacrifice the plane when things go Tango Uniform and begin to make bad choices.
Very simply, we need to have fuel delivery systems that meet some rational standard. This is no place to be experimenting on the first flight. The engines need to work and fuel stoppage or lack of fuel has been an ongoing problem in homebuilt aircraft.
Look at the long list of Sonex crashes and for the most part they are directly related, “first” to engine failure (multiple causes) and then the ensuing loss of control.
This is shameful on all our parts and needs to stop or big brother will fix it for us one way or the other. That or we will as a group, become so high risk, the insurance companies will price us out of the left seat.

Larry
Waiex121YX, Camit 3300, Skyview

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 3:12 pm

by vwglenn

My wife hates it when I watch shows like “Why Planes Crash” and such. I find myself often yelling at the TV as highly experienced pilots do the same stuff over and over and over again. I read the same thing in accident synopsis. I heard it from my flight instructor in the 90s. It was reinforced by my attendance in the FAA accident investigation course. Don’t stall the plane and your chances of survival increase dramatically.

FLY THE PLANE

Fly it into a wall. Fly it into trees. Fly it into a car. Fly it into a lake. Just make sure the plane is in controlled flight when you hit.

The most complex airliners with all the crazy gizmos to maintain flight don’t seem to help pilots with thousands of hours recognize and overcome this problem. I doubt AOAs and stall buzzers would change much when you’re panicked and the ground is coming up fast. You simply have to be mentally prepared to fly it until it stops moving. I heard about an accident where the guy had the correct rudder input but held the stick in his chest as he spun in a panic over 20 rotations. All he had to do was let go of the stick and he may have made it.

Practice. Practice. Practice. Engine or no engine. It’s still an airplane. It sill flies. Just not as far. We’ll learn a whole lot more about mysterious engine failures if we survive to tell the tale. I have my theory(s) about engine failure but they will remain as speculation until I have some sort of proof.

FLY THE PLANE!!!

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 5:43 pm

by SonexN76ET

All great points you have all made regarding stall/spin accidents.

A couple of things that I would like to add. When you try to stretch a glide in a Sonex by pulling the nose up, you actually dramatically increase the sink rate as the airplane slows. Close to the ground this will further increase the instinct to pull up which is completely counterproductive and will lead to the deadly stall spin. Train yourself to make your panic reaction a push down to increase airspeed to maintain best glide speed. The stall speed on the Sonex is around 40 mph. You can survive hitting just about anything at that speed. You can not survive a stall from even 30 feet. If you loose power just glide the plane down to as normal of landing as you can make and make gentle turns to avoid hitting the hardest stuff, but watch that airspeed.

I too am very concerned about the number of engine failures in the homebuilt community. It infuriates me when the NTSB comes back with a finding of loss of power for indeterminate reasons. They could at least say the engine may have failed because of X based on this circumstantial evidence or it could have failed because of Y based on a probable factors of ABC (or some such thing that would at least give us something that we could address as a community).

I would like to encourage everyone to use high quality, aircraft grade engine controls and fuel lines. This is not the place to experiment or to be cheap or worried about a couple of ounces.

I would like to see the EAA or FAA publish something on the ABC’s of inspecting critical systems. This would focus on the most critical items necessary for safe flight, such as fuel systems, engine controls, ignition systems, induction systems, and flight controls. Things that you really have to make sure are 100% bulletproof.

Please be safe out there and make sure you get the Sonex Transition Flight training before your first flight.

Thanks,

Jake

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 7:50 pm

by mike.smith

WaiexN143NM wrote:Hi all,
Now one into a condo roof in mass.

That is WILD SPECULATION!!! The NTSB is investigating and there is NO PROOF and NO INFORMATION that would lead anyone to believe, at this point, that it was a stall/spin. Please do not dishonor the life of my friend with completely unsubstantiated information.

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 8:33 pm

by lpaaruule

I couldn’t help but run the numbers on 40mph crash vs stalling at 30 feet.

According to this online calculator: http://keisan.casio.com/exec/system/1224835316

It takes a free fall from 53 feet to reach 40mph. 30 feet free fall would reach 30 mph. The stall would have air resistance, so it would be less than 30mph.

Just some data to ponder.

Regarding another post, I’d be interested to see data that shows non-standard Sonex fuel system engine-outs vs standard Sonex fuel system engine-outs. I don’t recall seeing that data anywhere.

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 10:55 pm

by rizzz

Even though I 100% agree with the statement that your best chances of survival are to fly the plane as long as you can into the crash, I totally disagree with the “you can survive pretty much anything at 40 mph” statement.

This might be almost always the case in a car, a Sonex is not at all built like a car, it does not have wrinkle zones, airbags etc.
If only your body were to impact the ground or anything else at 40 mph, it is a toss of a coin whether you’d survive or not, it would be about the same as an average size adult falling from a 2 to 3 story building, survivable, maybe, but only with a lot of luck.

In a Sonex you’d be a little more protected at the moment of impact but nothing like in a car, the G forces your body will experience in a Sonex crash will still be much greater than in a car crash at the same speed, purely because of the fact that the wrinkle zones of the car will absorb most of the G forces.

And lets put impact forces aside for a second,
Often the actual cause of death will not be excessive G forces your body experiences but rather severe head & spinal trauma, puncturing of vital organs etc from hitting things in the cockpit that your body is thrown towards and/or are thrown at your body.
Cars have many safety features we just cannot include into our airplane because of the weight concerns, for example, cars have mechanisms to pull the steering wheel away from you on impact.
Just imagine what will happen with that whole glareshield/fuel tank/instrument panel structure if you hit a wall nose first at 40 mph, it will come straight at you and in the meantime your head is moving straight towards it. If you do manage to miss it the recoil will then throw your head back again and guess what, there is no headrest to stop it like in a car which means your neck will be subjected to a severe whiplash event.

Anyway, I might have gone a bit too much into the horrible details but I just thought the statement made was a bit of a dangerous one and needed correction as it implied a sense of indestructibility as long as you stick to the don’t exceed 40 mph rule…

2

Re: Stall/spin accidents in our community

Posted: Wed Mar 01, 2017 11:18 pm

by samiam

rizzz wrote:Even though I 100% agree with the statement that your best chances of survival are to fly the plane as long as you can into the crash, I totally disagree with the “you can survive pretty much anything at 40 mph” statement.

This might be almost always the case in a car, a Sonex is not at all built like a car, it does not have wrinkle zones, airbags etc.
If only your body were to impact the ground or anything else at 40 mph, it is a toss of a coin whether you’d survive or not, it would be about the same as an average size adult falling from a 2 to 3 story building, survivable, maybe, but only with a lot of luck.

In a Sonex you’d be a little more protected at the moment of impact but nothing like in a car, the G forces your body will experience in a Sonex crash will still be much greater than in a car crash at the same speed, purely because of the fact that the wrinkle zones of the car will absorb most of the G forces.

And lets put impact forces aside for a second,
Often the actual cause of death will not be excessive G forces your body experiences but rather severe head & spinal trauma, puncturing of vital organs etc from hitting things in the cockpit that your body is thrown towards and/or are thrown at your body.
Cars have many safety features we just cannot include into our airplane because of the weight concerns, for example, cars have mechanisms to pull the steering wheel away from you on impact.
Just imagine what will happen with that whole glareshield/fuel tank/instrument panel structure if you hit a wall nose first at 40 mph, it will come straight at you and in the meantime your head is moving straight towards it. If you do manage to miss it the recoil will then throw your head back again and guess what, there is no headrest to stop it like in a car which means your neck will be subjected to a severe whiplash event.

Anyway, I might have gone a bit too much into the horrible details but I just thought the statement made was a bit of a dangerous one and needed correction as it implied a sense of indestructibility as long as you stick to the don’t exceed 40 mph rule…

Good points Michael, to which I’ll add -

  1. You are absolutely right about loose items causing head damage, which is why in any GA airplane, I think it is unacceptable to have anything loose in the cockpit that you wouldn’t want to hit you in the head at 50+mph

  2. Your point about the G loads is not exactly true. The analogy of jumping from a height of 2 or 3 stories is not really applicable to a 40mph accident, it’s analogous to a stall/spin accident, which is why it’s so fatal. The difference is that when you impact the ground, your deceleration distance is essentially zero so the G loads are very high. Rod Machado once did a piece on this, where he shows that the math behind it. As long as an airplane crashes at 50mph and slows over a distance of 10 feet or more, the G loads will not be fatal. This is why someone can crash into a building through a window and survive, but if they hit a brick wall they will not.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 12:03 am

by rizzz

samiam wrote:2. Your point about the G loads is not exactly true. The analogy of jumping from a height of 2 or 3 stories is not really applicable to a 40mph accident, it’s analogous to a stall/spin accident, which is why it’s so fatal. The difference is that when you impact the ground, your deceleration distance is essentially zero so the G loads are very high. Rod Machado once did a piece on this, where he shows that the math behind it. As long as an airplane crashes at 50mph and slows over a distance of 10 feet or more, the G loads will not be fatal. This is why someone can crash into a building through a window and survive, but if they hit a brick wall they will not.

Yes you are correct, in a controlled crash, if there is such a thing, with a bit of luck you will generally not be coming to an instant stop and I agree this is THE difference between a survivable and a non survivable crash.
I should have been more clear on this, I was focusing too much on the “you can survive pretty much anything at 40 mph” statement which implies you can fly straight into a brick wall at that speed.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 9:52 am

by Sonerai13

lpaaruule wrote:I couldn’t help but run the numbers on 40mph crash vs stalling at 30 feet.

One thing you didn’t consider is the angle of the impact. In a stall/spin, the impact is usually vertical, whereas if you’re flying the airplane into the ground at the same speed, the impact will be at an angle. And if you’re in control of the airplane you will be able to have some control over that angle of impact. So even though the speed may be the same, the energy dissipation will be spread out over a much longer time with an angular impact as opposed to the vertical. It does make a difference.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 10:53 am

by lpaaruule

Hi Joe,

Thanks for your comment. I understand what you are saying, and had considered it. Even in a car, the hope would be that you wouldn’t run into the back of another vehicle that’s standing still. I was only considering worst case, like we’ve seen automakers do when they send a vehicle into a solid wall.

Unless a plane is stalled, the angle of impact with the earth should be low. If it’s low enough, I call it a landing. The things sticking up from the earth at different angles is what I was considering.

I absolutely agree that flying the airplane and avoiding objects, or hitting them at an angle is preferable to a straight in impact.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 2:16 pm

by Onex107

I agree with the slow flight, best glide, AOA, training. I have experienced a cylinder loss in my Onex Aerovee (fouled plugs) and it will maintain altitude on three cylinders, at 2000 rpm, running rough, and you can milk out a 50-100 fpm climb at 60-70 mph. But it’s a very sensitive situation. A 30 degree turn would put you near stall speed.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 2:38 pm

by Onex107

I’d like to add one more thing. The AOA in my Onex cost about $65.00. It doesn’t light up, it doesn’t talk to you, and it doesn’t need 12 volts and a fuse. You can make one yourself. The plans are available on the internet. No voltage required, and you can calibrate it for flaps or no flaps by setting the angle of the probe, mounted on an inspection plate next to the pitot. All You have to purchase is the differential pressure gage. Mine is calibrated in Green, Yellow, and Red zones. The red zone starts at 45 mph. It’s within my sight zone while landing and I have come to rely on It during final approach. Short final airspeed is in the Yellow range. I don’t have to look at the airspeed indicator or GPS when my eyes should be outside. It’s mounted on top of the panel down in the corner on the left side where the windshield meets the panel. A couple of pieces of 1/4 aluminum, a differential pressure gage, and a few feet of plastic tubing and you have a functioning AOA.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 4:04 pm

by WaiexN143NM

Hi all,
For our second waiex, i ordered the lift pressure gauge and dynon pitot tubing kit from spruce. Will go on the left side of panel right in front of me. I agree , keep it seperate and simple, no electricty , wires, fuses, etc. it will always work with just air pressure.

WaiexN143NM
Michael

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 6:51 pm

by N190YX

I think it was Bob Hoover who recommended maintaining airspeed so you can fly the airplane as far as possible into the crash. When you stall close to the ground, you become a passenger. It is better to fly onto or into something than to loose control! Trees? Guide the fuselage between and let the wings come off as they absorb energy slowing down the fuselage. Having enough airspeed to flare and stop the descent when landing off airport is so much better than trying to stretch the glide and stalling and hitting hard.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 9:41 pm

by Ercoupechris

Unfortunately, Stall /spin accidents are the single largest cause of fatalities in general aviation… PERIOD!!!.. No one can know nor can the NTSB know for sure in the end, BUT, the fact is that the “Human Factor” is the least understood and most dangerous thing we face as pilots. When everything is going to hell in the cockpit, it takes us 5 times as long to react and our ability to maintain clear thought and do all of the right things to safely get to the ground is exponentially more difficult. This is why if you evaluate NTSB accident reports, even when engine failures occur, they always cite that the pilot failed to maintain controlled flight to the ground (paraphrasing). As we all know, airplanes don’t fall out of the sky nor do they hit immovable objects without guidance from the pilot. The best way to force yourself to learn these things is to practice slow flight and if possible, practice engine outs as much as you can and understand what the airplane is telling you. Experience and training (to include self training/practice) will aid you in using rote memory to overcome things in a more automatic fashion.

If you evaluate stall/spin accidents, to include hitting immovable objects, you will generally find that better options for where to put the plane down were available and but for the “Human factor” and our inability to process the situation with little if any time to spare, most are survivable. In the end, we have to NEVER stop flying the airplane since as long as it is flying, we have some control overt the situation. Trying to push the aircraft beyond Bernoulli’s principle (available LIFT) in hopes of making it one foot further forward than the airplane can fly, only hastens the speed at which we hit the ground or immovable objects.

Personally I’d rather land on a moving car or in tree tops or anywhere else that won’t create a sudden stop. Touching down at less angle and at or just above stall speed is the name of the game. We have to become the best energy managers that we can be and know that no matter what, the Human Factor and lack of experience will more than likely make us a statistic for which we cannot survive.

And for the record, I have survived one complete engine out that resulted in an off airport landing and a partial engine out that was nursed to the next airport. I am sure that other here can reflect on similar incidents. Had I been a low time pilot during either of my incidents, I likely would not have fared so well.

This is an important discussion that we should never be afraid to have, here, or anywhere else. I hope this doesn’t offend anyone but if so, so be it

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 10:27 pm

by fastj22

I’ve had two engine outs. I have an analog LRI (lift reserve indicator) gauge (AOA) that is mechanically/steam driven. It sits right in front of me. I think its saved my life and my plane. In both situations, I used that gauge to get me back on the ground. However, it takes discipline to fly to it. If you lose your head, and panic or get distracted, an LRI ain’t gonna do nothing for you. But if you can keep you head, keep the plane flying in the safe zone (the LRI will tell you that), you will land at a controllable and slow speed. Not to say it won’t be in the roof of a condo complex or in the case of my last landing, a frozen pasture.

Re: Stall/spin accidents in our community

Posted: Thu Mar 02, 2017 11:23 pm

by Ercoupechris

I agree with you John but flying for Vglide is also a good tool, gotta watch airspeed. In fact in the absence of Lift Reserve indication, I would be (and have been) scanning between the ASI (Vglide) and where you’re going to put it down. I agree though that if you have LR its great but if not, there are other options. No substitute for good energy management and making realistic choices on where you want to crash land.

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 9:49 am

by Sonerai13

Ercoupechris wrote:When everything is going to hell in the cockpit, it takes us 5 times as long to react and our ability to maintain clear thought and do all of the right things to safely get to the ground is exponentially more difficult.

this is the truth! I spoke to a gentleman many years ago, who had survived a stall/spin accident in his homebuilt. He had an engine failure and went down in trees. He told me that he KNEW he shouldn’t be pulling back on the stick, but he just couldn’t stop himself as the trees got closer. This is how our mind reacts. We have to train, train, train to instill the proper response to emergencies. Unfortunately, no training can simulate the rush of Adrenalin that will happen when the trees (or rocks, or whatever) get close and the whole thing is for real. But good training will help to alleviate the anxiety of the moment. Training, and recurrent training, is the key!

Be safe folks!!

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 11:03 am

by kmacht

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

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 12:12 pm

by gammaxy

I think the LRI is useful, but it’s not clear to me how it would make stall/spin accidents in a Sonex less likely.

I was practicing accelerated stalls yesterday and the ASI was indicating ~45mph at the stall which is about what it indicates during normal stalls. For my load factor, I would have expected to see ~80+mph on an airplane with a more typical pitot/static system. It seems that by placing the static port below the wing, the Sonex ASI already acts somewhat like a LRI in that the airplane stalls at approximately the same indicated speed regardless of positive load factor (at the expense of the indicated altitude being incorrect during the maneuver).

My point is, I doubt people are stalling or spinning while their ASI is reading typical approach or departure speeds. I don’t see how the LRI would remedy that problem.

A year or so ago I did some limited research into stall horns. The impression I got was that the fatal accident rate in certified aircraft decreased significantly about the time they became common. Unfortunately, it’s basically impossible to know whether the cause of the decrease was actually due to the stall horns–the pilots they save likely never realize the horn saved them. I remember hearing the horn a couple of times during my training while practicing emergency off-field landings. I do feel like there might be some value in making stall horns more common on Sonex. Personally, I’d like one a little nicer than the “on-off” buzzer style. I’d like one that changes tone or intensity as I get closer to the stall.

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 2:44 pm

by radfordc

I doubt that any cockpit instrument will ensure pilots don’t stall and spin when they are under stress…such as experiencing engine problems. Instinct is hard to overcome…and it seems instinctual to pull back on the stick when the ground is coming up fast. Training and experience should be the answer. I know that I felt better able to deal with engine problems after having flown ULs for over a 1000 hours and having many, many engine out landings…both intentional and otherwise. It sure helped when I had to make an engine out landing in a Sonex. Glider pilots make a deadstick landing every flight and seem to be OK with that. Do you suppose that if actual engine off landings were a required skill that stall/spin accidents would decline?

I think the first reaction to a serious engine problem could be “shut off the mags and fuel and fly the airplane”. I doubt many pilots would agree, and it seems more common to focus on the engine issues and not so much on flying the plane.

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 3:16 pm

by Bryan Cotton

How many of ur regularly practice slow flight, stalls, and spins? When I used to tow and fly gliders, it was a ton of slow flight. I did often practice stalls in everything I flew. I am overdue on spin practice. I don’t subscribe to the modern theory of stall awareness. Go out and do them.

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 3:36 pm

by vwglenn

The single biggest thing you can do is to practice before it happens. Being prepared for the worst will help you when the worst comes. Studies have shown that mid to higher time pilots are more apt to make pilot error mistakes. Low time pilots and ATPs are less likely.

I don’t think the comparison between the RV-12 and the Sonex is a good one when you’re talking about stalls and spins. It’s simply a pilot thing which, as eluded to earlier, is something of an intangible and won’t be known until the length of time the -12 is in service becomes equivalent to the Sonex. Until you can look at it over the same time interval or overall hours in service, that probably won’t ever come to a realistic comparison.

The thing that concerns me is not the pilot error issue but the engine failure issue. Specifically engine failures in the same regime of flight…on takeoff and climb with no definitive information as to why. This is the most deadly time to lose that engine and probably the hardest to fight your alligator instincts to get back to the runway or avoid the ground by pulling back on the stick and spinning it in. I would say this is the area that needs the most scrutiny. Using the number of accidents (39) mentioned above as a base line, I would say a half of those could be tracked back to a verifiable cause or contributing factor which makes the accident explainable and either preventable or simply a freak occurrence. Half of what’s left (8 or 9 of 20) happened while in takeoff/climb regime of flight with bad results and no explanation. This looks like a trend to me. I’m now hyper aware and mentally prepared every time I swing out onto the runway.

Is it going to stop me from flying my Sonex? Nope.
Will I take extra steps to mitigate potential pit falls? Yep.
Am I scared? Nope. Not until there is something to be scared of.

I’m infinitely more frightened of people staring at their phones while driving and much much more likely to die as a result. I still drive my car everyday.

Re: Stall/spin accidents in our community

Posted: Fri Mar 03, 2017 11:12 pm

by fastj22

A LRI or AOA gauge will not by itself save you from spinning into the ground. All it will tell you is when the wing won’t continue to fly. If you pay attention to it, it might allow you to walk away. If you don’t have one, or choose to ignore it, who knows.

Re: Stall/spin accidents in our community

Posted: Sat Mar 04, 2017 11:00 am

by LarryEWaiex121

Glenn,

I agree with most of your post.
Again, I go back to the engine failure rate and our accident rate in the Sonex community. I don’t have the resources to definitively say what is the main cause but suspect that fuel/carburation matters play a part in many of the accidents.
The comparison to the RV line is interesting in the initial numbers breakout. I would say without hesitation that the biggest reason that the raw numbers show this spread is hidden in a couple of well known facts. One, the RV 10 airplanes in particular, are very routinely “professionally built” by contractors and not some guy in his garage. Two, they are using either certified engines or copies of certified engines with essentially everything except the pedigree.
Its a shame we don’t have a certified engine at affordable cost for the Sonex line. Unfortunately, the cost, simplicity matter all force choices on us as builders. Personally I do all I feel that I can to keep my machinery up to snuff. I do my routine maintenance, I do my leakdown tests, etc. Beyond doing your due diligence its difficult to predict other issues.
In the end, one has to approach every flight with a healthy caring for the unpredictable and have your head screwed on with a plan. Easier said than done but, we all as a group have to try a bit harder. The numbers are kinda ugly.

Larry
Waiex121YX, Camit 3300, Skyview