The unstallable plane that stalled(fearoflanding.com)
fearoflanding.com
The unstallable plane that stalled
https://fearoflanding.com/accidents/accident-reports/the-unstallable-plane-that-stalled/
182 comments
> nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot.
An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick.
My dad (fighter pilot) told me that knowing exactly where the stall point is is life and death. When you're in a dogfight, the winner often is the one that can turn inside the other. Turning as tight as you can requires getting exactly on that edge of the burble.
It's the same thing as in automobile and motorcycle racing. How close you can get to a slide without sliding is the difference between victory and ignominy.
An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick.
My dad (fighter pilot) told me that knowing exactly where the stall point is is life and death. When you're in a dogfight, the winner often is the one that can turn inside the other. Turning as tight as you can requires getting exactly on that edge of the burble.
It's the same thing as in automobile and motorcycle racing. How close you can get to a slide without sliding is the difference between victory and ignominy.
> An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick.
Without any disrespect to the flying abilities of your Dad, as an aerospace engineer, the short answer to that is "no".
You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning. You have absolutely no guarantee that once the airplane has been modified beyond its original configuration, you will get any form of warning. This extreme behavior is actually partly present in the current case, with the stalling point jumping from the wing tip immediately to the wing root. That's no good.
It can be even worse if you're flying a plane that is licensed under the "experimental" category by the FAA. One of the preferred airfoil for some time was the NACA 5-series, as it can have very little lift-induced pitching moment. It has also criminal stalling characteristics with absolutely no warning. Something beautifully illustrated by the following lift polar:
https://media.cheggcdn.com/media/76b/76b33250-7f26-41f6-8f2c...
Without any disrespect to the flying abilities of your Dad, as an aerospace engineer, the short answer to that is "no".
You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning. You have absolutely no guarantee that once the airplane has been modified beyond its original configuration, you will get any form of warning. This extreme behavior is actually partly present in the current case, with the stalling point jumping from the wing tip immediately to the wing root. That's no good.
It can be even worse if you're flying a plane that is licensed under the "experimental" category by the FAA. One of the preferred airfoil for some time was the NACA 5-series, as it can have very little lift-induced pitching moment. It has also criminal stalling characteristics with absolutely no warning. Something beautifully illustrated by the following lift polar:
https://media.cheggcdn.com/media/76b/76b33250-7f26-41f6-8f2c...
> You will have the luck to feel a "burble" if the airplane has been been built to be give you that warning.
Airplanes which are designed to do this (most airplanes) do it very reliably, it's not luck. Several of the Citabrias I fly don't have stall horns, all I have is the buffet.
Complexity is always a tradeoff: it's harder to fuck up building and/or repairing a simpler airfoil.
Airplanes which are designed to do this (most airplanes) do it very reliably, it's not luck. Several of the Citabrias I fly don't have stall horns, all I have is the buffet.
Complexity is always a tradeoff: it's harder to fuck up building and/or repairing a simpler airfoil.
> Several of the Citabrias I fly don't have stall horns, all I have is the buffet.
That's fine, as long as the airfoil and wing planform you chose have a forgiving-enough lift vs angle-of-attack curve that you get plenty of buffeting before you start loosing significant lift and fall out of the sky.
> Airplanes which are designed to do this (most airplanes) do it very reliably
Yes, this is by design. Enough pilots were killed because their planes were not doing this reliably, and they literally fell out of the sky.
That's fine, as long as the airfoil and wing planform you chose have a forgiving-enough lift vs angle-of-attack curve that you get plenty of buffeting before you start loosing significant lift and fall out of the sky.
> Airplanes which are designed to do this (most airplanes) do it very reliably
Yes, this is by design. Enough pilots were killed because their planes were not doing this reliably, and they literally fell out of the sky.
Is it possible there's a mechanical/design cutoff where most planes designed to be fully mechanical would feel the "burble" while a more modern plane would not, similar to ABS vs non-ABS brakes or powersteering vs none? Are there hydraulic assists for flight controls that might smooth out those mechanical tells?
Not necessarily, no.
It's a design feature to give pilots an advanced, physical warning that they are about to stall, and fall out of the sky. Electronic systems are all nice an well, but they can fail. So why not simply make it a physical feature of your airplane design, that triggers reliably not matter what?
In some very specific edge cases a designer might decided that the planform trade-offs needed to bake the feature into the wing is not worth the performance loss in other metrics, and might forgo a nice, buffeting pre-stall wing. But plenty of pilots have died because they unexpectedly stalled, so it is not a design decision that should be taken lightly.
It's a design feature to give pilots an advanced, physical warning that they are about to stall, and fall out of the sky. Electronic systems are all nice an well, but they can fail. So why not simply make it a physical feature of your airplane design, that triggers reliably not matter what?
In some very specific edge cases a designer might decided that the planform trade-offs needed to bake the feature into the wing is not worth the performance loss in other metrics, and might forgo a nice, buffeting pre-stall wing. But plenty of pilots have died because they unexpectedly stalled, so it is not a design decision that should be taken lightly.
Sure, that's why I said "airplane like this": in car terms, the plane we're talking about here is a minivan.
Imagine dogfighting in a Cessna! I imagine the arms to be pilot wielded colt 45s and first officer to be a jug of whiskey.
One of the last aircraft shot down in the European theater of WWII was a Piper Cub that shot down a Fieseler Storch with a .45 pistol. They landed next to the crashed Storch, captured the pilot, and treated his injuries. Then handed him over to the Russians, who I am sure also treated him in accordance with the provisions of the Geneva convention.
https://theaviationgeekclub.com/that-time-a-usaaf-piper-l-4h...
https://theaviationgeekclub.com/that-time-a-usaaf-piper-l-4h...
Perhaps in accordance with the spirit, but the Geneva convention was in 1949, so those provisions didn't exist yet.
There were several Geneva Conventions prior to the 1949 one; the "Convention relative to the Treatment of Prisoners of War" was signed in 1929.
https://ihl-databases.icrc.org/en/ihl-treaties/gc-pow-1929
https://ihl-databases.icrc.org/en/ihl-treaties/gc-pow-1929
The current Geneva Convention was in 1949, but the original Geneva Convention dates back to 1864.
Of course, the previous poster is noting that the USSR blithely disregarded the conventions for others' POWs as well as its own: most returning soldiers were considered traitors to the Motherland and summarily executed or sent to the Gulag to die more slowly.
Of course, the previous poster is noting that the USSR blithely disregarded the conventions for others' POWs as well as its own: most returning soldiers were considered traitors to the Motherland and summarily executed or sent to the Gulag to die more slowly.
if you like that idea and science fiction, see the second book in the Greatwinter trilogy by Sean McMullen (read them in order, though)
Love this description lol
> An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick
Stall recovery has also been an essential part of my flight training.
Stall recovery has also been an essential part of my flight training.
The most dangerous situations are when you're flying low and slow like before a landing though, when there's often no time for recovery (especially when you end up in a spin due to asymmetric stall). When I was flying I always worried about this too the point of approaching too fast. But I never finished my PPL anyway
Although can you recover at a height 15m above terrain?
. . . probably not, but does that mean you never practice? Most stall/spin incidents occur at low altitude, but not THAT low. It's often pilot inattention in the landing pattern.
I agree! IANAP though.
Also in this case I suspect they needed to learn proper takeoff procedure. Since you can’t practice dying more than once the mitigation has to be avoidance (in addition to the stall practice you mentioned)
Also in this case I suspect they needed to learn proper takeoff procedure. Since you can’t practice dying more than once the mitigation has to be avoidance (in addition to the stall practice you mentioned)
Technically, power-on stalls are supposed to teach how to recover from bad technique on takeoff/go-around and power-off stalls are supposed to teach how to recover from bad technique in the landing pattern.
In reality, they're both training-wheels versions of how to deal with any departure from controlled flight, which is why any professional pilot worth their salt should have a decent grounding in aerobatics and some spin/departure/out-of-control flight experience.
-Am (or at least was) a pilot . . . I could jump in and fly a bugsmasher today if I really needed to, just not legally without a doc visit and a checkride.
In reality, they're both training-wheels versions of how to deal with any departure from controlled flight, which is why any professional pilot worth their salt should have a decent grounding in aerobatics and some spin/departure/out-of-control flight experience.
-Am (or at least was) a pilot . . . I could jump in and fly a bugsmasher today if I really needed to, just not legally without a doc visit and a checkride.
Not really, as to your final point; the race driver’s skill is not in avoiding the slide, but — with the mechanic’s help — finding it, and using it. Recall: loose is fast, and on the edge of out of control.
I'll admit to complete and total ignorance, but:
> ...we just use the number the manufacturer publishes.
From the article it sounds like this plane was radically modified, to the point where the manufacturer's stall speed would be irrelevant.
Why wouldn't you want to confirm for yourself where the speed is after so many changes?
> ...we just use the number the manufacturer publishes.
From the article it sounds like this plane was radically modified, to the point where the manufacturer's stall speed would be irrelevant.
Why wouldn't you want to confirm for yourself where the speed is after so many changes?
Radical has all the wrong implications. It's a "major alteration" in a regulatory sense, done from an approved kit of parts, with a very well documented installation and post-installation operation and maintenance procedures.
The aircraft was modified with a Robertson STOL kit. A common type of modification to make to a "bush aircraft". In the USA the modification is covered by an STC (Supplemental Type Certificate), the installation needs to be supervised and approved by an A&P technician with IA (Inspection Authority). The STC will modify the airspeed indicator markings, including the stall speed markings (bottom of green and white arcs), and modify the approved flight manual/pilot operating handbook and maintenance documentation for the aircraft. Since this is a major alteration (in a 14CFR regulatory sense) that modifies the flight characteristics of the aircraft it needs to be test flown after the work, and the STC will also separately requires this. I expect/hope the STC includes instructions for checking stall characteristics including airspeed. In European countries a similar level of regulation/documentation is followed based on the USA STC.
Give the description of the pilot's sad lack of understanding of basic operation of the aircraft I am doubting they even read the pilot operating handbook.
The aircraft was modified with a Robertson STOL kit. A common type of modification to make to a "bush aircraft". In the USA the modification is covered by an STC (Supplemental Type Certificate), the installation needs to be supervised and approved by an A&P technician with IA (Inspection Authority). The STC will modify the airspeed indicator markings, including the stall speed markings (bottom of green and white arcs), and modify the approved flight manual/pilot operating handbook and maintenance documentation for the aircraft. Since this is a major alteration (in a 14CFR regulatory sense) that modifies the flight characteristics of the aircraft it needs to be test flown after the work, and the STC will also separately requires this. I expect/hope the STC includes instructions for checking stall characteristics including airspeed. In European countries a similar level of regulation/documentation is followed based on the USA STC.
Give the description of the pilot's sad lack of understanding of basic operation of the aircraft I am doubting they even read the pilot operating handbook.
As noted in the article, the plane had been modified with far more than just the STOL kit.
> A further issue was that his Cessna 185 had been extensively modified. The addition of floats, cargo pack, short take-off and landing kit and a three-blade propeller had never had their combined effect documented.
That’s a lot of things that modify the flight characteristics of a plane, all interacting together in what seems to be a previously untested configuration.
I can completely see how each individual modification might modify the planes flight characteristics in a well know manner. But I struggle to see how anyone could realistically predict the result of all the modifications without some basic empirical testing.
> A further issue was that his Cessna 185 had been extensively modified. The addition of floats, cargo pack, short take-off and landing kit and a three-blade propeller had never had their combined effect documented.
That’s a lot of things that modify the flight characteristics of a plane, all interacting together in what seems to be a previously untested configuration.
I can completely see how each individual modification might modify the planes flight characteristics in a well know manner. But I struggle to see how anyone could realistically predict the result of all the modifications without some basic empirical testing.
A three bladed prop modification along with floats is very common. Wipaire, the leading float manufacturer has its own STC for that. In combination with STOL kits is not uncommon either. I expect the Robinson STOL STC explicitly accommodates floats (Wipaire’ STOL STC sure do) but not sure since I don’t have the paperwork in front of me.
You are over inflating issues here. Are you a pilot? The issue here is straight up incompetent operation of an aircraft.
Operating a floatplane and separately operating with a STOL kits can increase complexity and risks especially when aircraft are mishandled/abused like here with an incompetent pilot who does not know what they are doing. You don’t need to dream up issues from combination of stuff here, the simple linear addition of issues was more than enough for an incompetent pilot to get into trouble, and seems they are lucky they did not get into more trouble before, and lucky they were not killed.
The C185 is a beautiful well behaved workhorse used extensively in bush and floatplane flying, often with multiple STCs to upgrade these aircraft.
You are over inflating issues here. Are you a pilot? The issue here is straight up incompetent operation of an aircraft.
Operating a floatplane and separately operating with a STOL kits can increase complexity and risks especially when aircraft are mishandled/abused like here with an incompetent pilot who does not know what they are doing. You don’t need to dream up issues from combination of stuff here, the simple linear addition of issues was more than enough for an incompetent pilot to get into trouble, and seems they are lucky they did not get into more trouble before, and lucky they were not killed.
The C185 is a beautiful well behaved workhorse used extensively in bush and floatplane flying, often with multiple STCs to upgrade these aircraft.
I get what you're saying, and I agree this sounds like operator negligence to me.
But the article does say that investigators had to get another aircraft set up with the same modifications and fly it around with bits of wool all over it in order to understand the stall characteristics.
So I assume this plane setup isn't so widespread that its stall behaviour is common knowledge.
But the article does say that investigators had to get another aircraft set up with the same modifications and fly it around with bits of wool all over it in order to understand the stall characteristics.
So I assume this plane setup isn't so widespread that its stall behaviour is common knowledge.
My understanding is that in the US, part of the modification would be updating the plane's official operating limitations, and there could be a new stall number. Still a number from the manufacturer, not a number empirically determined by testing that specific airplane. For special one-off modifications, I don't know: I've always been told that's almost impossible with certified airplanes.
One Citabria I've flown had vortex generators installed on the leading edge of the wings, but the club sold it over a year ago and I don't remember if it listed a modified stall speed. I do remember it said "not airworthy if more than N of the VGs are broken off", I think it was three?
One Citabria I've flown had vortex generators installed on the leading edge of the wings, but the club sold it over a year ago and I don't remember if it listed a modified stall speed. I do remember it said "not airworthy if more than N of the VGs are broken off", I think it was three?
The plane had a cargo pack and a Robertson STOL. Cargo packs are essentially for bush planes and as an example, the 1975 Skywagon’s owners manual even had one diagrammed. Robertson STOL’s are extremely common in Northern Canada to the point that even as a passenger I know about them.
It’s nothing too radical.
Edit - Here’s a copy of the 1975 owners manual:
https://www.seaplanescenics.com/documents/1975-cessna-185f-p...
It’s nothing too radical.
Edit - Here’s a copy of the 1975 owners manual:
https://www.seaplanescenics.com/documents/1975-cessna-185f-p...
Stall speed depends on so many factors that it can change significantly in a single flight.
Weight, altitude, density altitude, angle of attack etc. are all going to have an effect.
In other words, sure, you might want to confirm it, but you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall.
Weight, altitude, density altitude, angle of attack etc. are all going to have an effect.
In other words, sure, you might want to confirm it, but you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall.
> angle of attack etc
This is wrong.
The angle of attack is not a parameter of the stall speed, it is the cause of the stall (for a given configuration, assuming well below transonic speed). This is why for example, for precise handling you should use an angle-of-attack indicator (a large majority of fighter jets and more generally military aicraft have it).
> you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall
The manufacter speed already take into account the afore-mentioned parameters into account, and the resulting speed is the worst case scenario, if not told otherwise (usually max weight, max forward CG).
One should not fly with an arbitrary speed margin, but instead use well-known speedq (1.3Vs, 1.45Vs, where Vs=stall speed in the given config) depending on the flight phase, and remember well the bank angle limit associated with them.
This is wrong.
The angle of attack is not a parameter of the stall speed, it is the cause of the stall (for a given configuration, assuming well below transonic speed). This is why for example, for precise handling you should use an angle-of-attack indicator (a large majority of fighter jets and more generally military aicraft have it).
> you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall
The manufacter speed already take into account the afore-mentioned parameters into account, and the resulting speed is the worst case scenario, if not told otherwise (usually max weight, max forward CG).
One should not fly with an arbitrary speed margin, but instead use well-known speedq (1.3Vs, 1.45Vs, where Vs=stall speed in the given config) depending on the flight phase, and remember well the bank angle limit associated with them.
> The angle of attack is not a parameter of the stall speed, it is the cause of the stall
You're right of course, based on the real definition of angle of attack which is based on relative wind. When people say angle of attack is a parameter of stall speed, they're separating speed from pitch.
This isn't really useful but people seem to struggle with the concept of relative wind, so it's a kind of shorthand.
You're right of course, based on the real definition of angle of attack which is based on relative wind. When people say angle of attack is a parameter of stall speed, they're separating speed from pitch.
This isn't really useful but people seem to struggle with the concept of relative wind, so it's a kind of shorthand.
This is what I was getting at. Thanks.
Also there’s planes that have slats and other devices that effectively change the angle of attack of the wing.
And then there’s planes that direct prop wash over the wing so that the power on stall speed is much lower than power off despite the angle of attack being different.
Also there’s planes that have slats and other devices that effectively change the angle of attack of the wing.
And then there’s planes that direct prop wash over the wing so that the power on stall speed is much lower than power off despite the angle of attack being different.
As Juan Browne (blancolirio) likes to say, you can stall a wing at any airspeed and any attiude but only one critical angle of attack.
How do you determine a margin without some form of a baseline?
You read the operator’s handbook which will give you that information.
In a certified aircraft the manufacturer has already done the test flying
In a certified aircraft the manufacturer has already done the test flying
Your airplane can also be in the "experimental" category, which generally means "homebuilt" so the stall speeds and characteristics can only be determined through test flight. I made the decision to empirically demonstrate stall speeds on the very first flight of my homebuilt, before attempting to land, so I knew for sure what they were.
I also have a homebuilt, and went and found out my stall speed.
But most homebuilts will still have a stall speed for planes built to plan.
In any case, this is an article about a Cessna. Where the stall speed is in the POH and also marked on the ASI.
But most homebuilts will still have a stall speed for planes built to plan.
In any case, this is an article about a Cessna. Where the stall speed is in the POH and also marked on the ASI.
[deleted]
European pilot here :) it's also not a European thing. It works the same here as it does in the US, you use the published number in the flight manual.
But this plane had significant modifications done. And if you do things that significantly change performance, you'll need to get updated performance data. Or the provider of the supplemental type certificate that allows the modification has to provide an updated flight manual with that data.
But this plane had significant modifications done. And if you do things that significantly change performance, you'll need to get updated performance data. Or the provider of the supplemental type certificate that allows the modification has to provide an updated flight manual with that data.
I'm not a pilot or an aviation expert, but I think you're arguing against a strawman here. The investigation report said nothing about determining the precise stall speed, it just recommended "that pilots be informed about the stall behaviour of the Robertson short take-off and landing kit on the Cessna 185 aircraft, both by listing the issue in the aircraft flight manual supplement and through education through the aviation authority". The fact that the stall speeds were not listed on the test flight report was just further proof that the pilot didn't actually test the stall behaviour of the aircraft.
What the investigation report also didn't mention is that pilots should actually practice stall recovery and not just think "if I believe strongly enough that my plane is unstallable, I can ignore stall recovery". But that probably goes without saying...
What the investigation report also didn't mention is that pilots should actually practice stall recovery and not just think "if I believe strongly enough that my plane is unstallable, I can ignore stall recovery". But that probably goes without saying...
> It's normal for airplanes of the same model to fly differently
In my experience any equipment this large is effectively handmade, with all the variability implied by this. I'd hope aircraft are made to tighter tolerances than the stuff I work with but a couple of millimeters is often enough to have a noticeable effect on things like actuator travel.
> nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot.
This is exactly my takeaway as well. Rather than trying to determine the characteristics of the machine to the n'th degree, assume a realistic degree of variation and design for it accordingly.
In my experience any equipment this large is effectively handmade, with all the variability implied by this. I'd hope aircraft are made to tighter tolerances than the stuff I work with but a couple of millimeters is often enough to have a noticeable effect on things like actuator travel.
> nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot.
This is exactly my takeaway as well. Rather than trying to determine the characteristics of the machine to the n'th degree, assume a realistic degree of variation and design for it accordingly.
> It is not necessary to empirically determine a specific airplane's stall speed in order to operate it safely. It's not required in the US, we just use the number the manufacturer publishes.
It is not necessary as in "there is no legal obligation", true.
But if you want to live, it is absolutely necessary. The numbers provided by the manufacturer will tell you absolutely nothing about the stalling characteristics of the airplane as soon as you start modifying it.
The non-linearity of the phenomena involved in stalling also mean that "intuition" and "small changes" will be of absolutely not help to determine by how much you changed the characteristics of your airplane.
It is not necessary as in "there is no legal obligation", true.
But if you want to live, it is absolutely necessary. The numbers provided by the manufacturer will tell you absolutely nothing about the stalling characteristics of the airplane as soon as you start modifying it.
The non-linearity of the phenomena involved in stalling also mean that "intuition" and "small changes" will be of absolutely not help to determine by how much you changed the characteristics of your airplane.
> nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot
Citabria's are often flown in aerobatics (Citabria backwards is airbatic and for a while, they were the only aerobatic aircraft being commercially manufactured in the US) and a lot of aerobatic maneuvers involve stalling the wing.
Citabria's are often flown in aerobatics (Citabria backwards is airbatic and for a while, they were the only aerobatic aircraft being commercially manufactured in the US) and a lot of aerobatic maneuvers involve stalling the wing.
Yes, but anyone doing aerobatics so close to the ground that they can't recover from a stall is understood to be doing that at their own risk.
Anyone doing the above with unfavorable wind has a death wish.
Anyone doing the above with unfavorable wind has a death wish.
You don't really look at the airspeed indicator for that, you feel the stall in the reversible controls. That feel is incredibly precise.
Decreases the stall speed? How does that work?
Things that can influence stall speed include weight, power, center of gravity, flaps/landing gear configuration, and more.
Why? Well, stall speed isn't a real thing. There isn't a speed at which you stall, that's not how it works. It's a convenient short-hand that we use for the more complicated reality. The physical reality is that stalls happen at a particular angle of attack (AOA) into the apparent wind. That is, the angle of your wings relative to the airflow. Up to the critical angle a higher AOA means more lift to counteract gravity. As you slow down you generate less lift because there's less airflow over the wings. So as you slow down, in order to generate a similar amount of lift you have to increase your AOA. If you keep slowing down and adjusting your AOA to compensate, you'll reach a speed that's low enough and therefore AOA high enough that adding more AOA no longer adds more lift (the air no longer flows smoothly over the wing). That's the stall speed, the speed at which more AOA no longer generates more lift. But it's the AOA that's the problem, not the airspeed.
In addition to lower speeds needing more AOA, you also need a higher AOA if you weigh more. A wrong but illustrative way to think about it might be that you need the engine's thrust pointed more towards the ground the more you weigh. That means that as you burn fuel (lose weight) the AOA that will stall you doesn't change, but the excess AOA available due to your weight-change does so in effect the air speed at which you would be near the critical AOA to stay airborn does change.
Stall speed is still a useful concept especially while landing but it's misleading outside of landing and when anything else is remotely unusual like weight or modifications to the plane. For this reason the FAA has been trying to get AOA indicators installed in planes and to train pilots to look at those instead of thinking about stall speeds https://www.faa.gov/sites/faa.gov/files/2022-01/Angle%20of%2...
Why? Well, stall speed isn't a real thing. There isn't a speed at which you stall, that's not how it works. It's a convenient short-hand that we use for the more complicated reality. The physical reality is that stalls happen at a particular angle of attack (AOA) into the apparent wind. That is, the angle of your wings relative to the airflow. Up to the critical angle a higher AOA means more lift to counteract gravity. As you slow down you generate less lift because there's less airflow over the wings. So as you slow down, in order to generate a similar amount of lift you have to increase your AOA. If you keep slowing down and adjusting your AOA to compensate, you'll reach a speed that's low enough and therefore AOA high enough that adding more AOA no longer adds more lift (the air no longer flows smoothly over the wing). That's the stall speed, the speed at which more AOA no longer generates more lift. But it's the AOA that's the problem, not the airspeed.
In addition to lower speeds needing more AOA, you also need a higher AOA if you weigh more. A wrong but illustrative way to think about it might be that you need the engine's thrust pointed more towards the ground the more you weigh. That means that as you burn fuel (lose weight) the AOA that will stall you doesn't change, but the excess AOA available due to your weight-change does so in effect the air speed at which you would be near the critical AOA to stay airborn does change.
Stall speed is still a useful concept especially while landing but it's misleading outside of landing and when anything else is remotely unusual like weight or modifications to the plane. For this reason the FAA has been trying to get AOA indicators installed in planes and to train pilots to look at those instead of thinking about stall speeds https://www.faa.gov/sites/faa.gov/files/2022-01/Angle%20of%2...
This is a good resource:
https://ciechanow.ski/airfoil/
Useful to think of the airplane as standing still while the engine accelerates the air around it. To fly, you need the air to move over the wings quickly and in the right direction.
You can sort of trade how fast you need the air to go for how ideally the air is flowing over the wings. If you angle the wings just right against the air flow, and/or you bend them out of shape just right with flaps, you can slow down a lot while relying on the air itself to carry your plane. If you're flying against the airflow, you need to go faster.
This is usually done during take off and landing. The pilot lowers the flaps when approaching to land and flares the aircraft before touchdown, all to make the air flow efficiently into the wings, thereby allowing the aircraft to slow down without falling straight down like a stone.
That's why weather is so important for flights. Pilots need to be ready to call TOGA and go maximum thrust at a moment's notice just in case some crosswind or heat wave or something screws up the direction of the air flow just as they're about to land. Many an admiral cloudberg article has been written due to that sort of thing. You angle the plane just right, slow it down just to the edge of stalling, then some phenomenon happens and increases your stall speed past your current speed...
https://ciechanow.ski/airfoil/
Useful to think of the airplane as standing still while the engine accelerates the air around it. To fly, you need the air to move over the wings quickly and in the right direction.
You can sort of trade how fast you need the air to go for how ideally the air is flowing over the wings. If you angle the wings just right against the air flow, and/or you bend them out of shape just right with flaps, you can slow down a lot while relying on the air itself to carry your plane. If you're flying against the airflow, you need to go faster.
This is usually done during take off and landing. The pilot lowers the flaps when approaching to land and flares the aircraft before touchdown, all to make the air flow efficiently into the wings, thereby allowing the aircraft to slow down without falling straight down like a stone.
That's why weather is so important for flights. Pilots need to be ready to call TOGA and go maximum thrust at a moment's notice just in case some crosswind or heat wave or something screws up the direction of the air flow just as they're about to land. Many an admiral cloudberg article has been written due to that sort of thing. You angle the plane just right, slow it down just to the edge of stalling, then some phenomenon happens and increases your stall speed past your current speed...
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The Robertson STOL mod droops the ailerons with flaps, changing the effective angle of incidence of the wing. A friend had a Robinson-equipped 182 and we could quite comfortably operate in/out of Marlboro Airport (1650' paved with trees at one end and a fence at the other).
That's not TERRIBLY impressive, considering a stock 182P has a 50' obstacle take off distance of 1350' of at max gross on an ISA day
The published speed is at maximum takeoff weight, with the most unfavourable center of gravity (usually most forward) and idle power
If the conditions are better (not at max weight, rear center of gravity, engine power adding more airflow over the wings) you can fly below the published stall speed number.
If the conditions are better (not at max weight, rear center of gravity, engine power adding more airflow over the wings) you can fly below the published stall speed number.
Yeah I was thinking backward. Lower stall speed is better, not worse behavior.
Soapbox: Stall speed is an approximation. It's baffling that GA aircraft don't have one of the most safety-critical measurements: AOA. Stall airspeed varies with a number of factors; this includes the mods described in the article, and weight change from burning fuel, passengers, payload etc. AOA is more invariant to that as a metric for choosing stall speed, speed down final etc.
I was very skeptical of this until I had the chance to fly one of those brand-new C172 models that come equipped with 'em. They're so convenient!
Sure, ye olde haptic feedback + inner ear + stall horn/shaker combo has always worked for me—but if you are a new or overwhelmed or complacent or unlucky pilot, having a big angry indicator sitting atop the glare shield furiously (visually & audibly) informing you of the approaching cross-control stall that is about to bury you in your base-to-final grave makes danger IMPOSSIBLE to miss.
The LEDs were bright enough to be clearly visible even under direct sun, but the Geiger-esque clicking and chattering increasing in urgency as I approached critical AoA made it for me. No need to put your head down or even alter your scan to include it: you can hear trouble coming!
Sure, ye olde haptic feedback + inner ear + stall horn/shaker combo has always worked for me—but if you are a new or overwhelmed or complacent or unlucky pilot, having a big angry indicator sitting atop the glare shield furiously (visually & audibly) informing you of the approaching cross-control stall that is about to bury you in your base-to-final grave makes danger IMPOSSIBLE to miss.
The LEDs were bright enough to be clearly visible even under direct sun, but the Geiger-esque clicking and chattering increasing in urgency as I approached critical AoA made it for me. No need to put your head down or even alter your scan to include it: you can hear trouble coming!
This +++. Most important parameter is AoA and we only have poor proxy for it in most GA. Nuts
Soapbox next to your soapbox: GA planes are old specifically because of the FAA and their overly restrictive regulations. The cost involved to create an AoA sensor & readout is minimal and at least one company has done it with an IMU only. The cost to certify, sell, and install an AoA sensor (in terms of both money and time waiting to get on the schedule of an FAA-blessed installer) is more than most people find it to be worth. Food for thought: this also applies to shoulder harnesses in many cases.
Aviation could be cheaper, safer, and better in general if the FAA was not stuck in the 60s.
Aviation could be cheaper, safer, and better in general if the FAA was not stuck in the 60s.
AoA indicators are able to be installed in certified aircraft as minor modifications, per the FAA policy from 2014.
There are FAA regulations that are overly conservative IMO, but I think the FAA has a sensible stance on AoA indicators.
There are FAA regulations that are overly conservative IMO, but I think the FAA has a sensible stance on AoA indicators.
CS-SC251c in the EU.
I don't think that's completely true. There is a combination of market size and regulatory burden; not a lot of people are buying GA aircraft (compared to say, the number of people buying iPhones), so there isn't an enormous financial incentive to get people out of their C172 or Bonanza.
I also think that these old airplanes are really ships of theseus. Maybe there are some original stickers and seats, but that's about it. Safety and avionics upgrades on these old airframes are definitely in the financial reach of many readers of this forum, and I'm sure many people are flying "old" airplanes that have AoA sensors and IFR-certified glass panels and backups. Day to day they probably feel a lot like airline pilots.
I also think that these old airplanes are really ships of theseus. Maybe there are some original stickers and seats, but that's about it. Safety and avionics upgrades on these old airframes are definitely in the financial reach of many readers of this forum, and I'm sure many people are flying "old" airplanes that have AoA sensors and IFR-certified glass panels and backups. Day to day they probably feel a lot like airline pilots.
> many people are flying "old" airplanes that have AoA sensors and IFR-certified glass panels and backups
Yes and no. They're out there, but they aren't as common as you'd think or hope. AoA in particular is rare. There's an awful lot of planes that are still running GNS430 or GNS530s (probably more than any other single setup), and more than a few with the original nav/comm equipment like the KX170B. A real glass panel (something like the G1000 or G3X) is really rare in an old plane. Maybe 5-10%?
Yes and no. They're out there, but they aren't as common as you'd think or hope. AoA in particular is rare. There's an awful lot of planes that are still running GNS430 or GNS530s (probably more than any other single setup), and more than a few with the original nav/comm equipment like the KX170B. A real glass panel (something like the G1000 or G3X) is really rare in an old plane. Maybe 5-10%?
The FAA is stuck in the 60's because there is a massive industry supporting the ancient technologies in general aviation.
Modern stuff, like you point out, is far more reliable, cheaper, lower power consumption, and more functional. That better reliability means less need for aircraft mechanics and avionics shops.
Nobody would want their discreet component transponder overhauled if it could be replaced with a cheaper unit that uses modern wizardry like logic chips or even (gasp) a microcontroller.
Ditto for leaded fuel air cooled piston engines with manual mixture controls that require teardowns all the time. That bullshit is only still around because Continental and Lycoming want it to.
Modern stuff, like you point out, is far more reliable, cheaper, lower power consumption, and more functional. That better reliability means less need for aircraft mechanics and avionics shops.
Nobody would want their discreet component transponder overhauled if it could be replaced with a cheaper unit that uses modern wizardry like logic chips or even (gasp) a microcontroller.
Ditto for leaded fuel air cooled piston engines with manual mixture controls that require teardowns all the time. That bullshit is only still around because Continental and Lycoming want it to.
This type of protectionism is exactly what I was referring to above. It's the single most frustrating aspect of aviation.
Yeah and because of that we're also still exposed to lead fumes and pollution :(
It's really time for GA to get into this century.
It's really time for GA to get into this century.
My favorite anecdote I heard of from a flight instructor is that of a cargo plane taking off that had some heavy vehicle tied down in its hold. It broke free of its straps during takeoff and rolled to the back of the aircraft, which shifted the CG such that the plane entered an unrecoverable stall and crashed.
I’m not sure if this is the one your instructor was referencing, but there was a fairly notorious such event in Afghanistan about a decade ago.
https://en.wikipedia.org/wiki/National_Airlines_Flight_102
https://www.faa.gov/lessons_learned/transport_airplane/accid...
https://en.wikipedia.org/wiki/National_Airlines_Flight_102
https://www.faa.gov/lessons_learned/transport_airplane/accid...
Also the excellent (as usual) write up from Admiral Cloudberg https://admiralcloudberg.medium.com/strength-in-numbers-the-...
There is a video which makes its way around the Internet regularly of this crash[1] which was attributed to exactly that, killing all seven on board. (Which makes it pretty heavy for an anecdote, admittedly.)
[1] https://en.wikipedia.org/wiki/National_Airlines_Flight_102
[1] https://en.wikipedia.org/wiki/National_Airlines_Flight_102
> Stall speed is an approximation. It's baffling that GA aircraft don't have one of the most safety-critical measurements: AOA.
All aircraft equipped with a six pack, you have an artificial horizon indicator which can tell you what is your angle of attack. And Cessna's have them in all planes, even 50-60 years old ones.
All aircraft equipped with a six pack, you have an artificial horizon indicator which can tell you what is your angle of attack. And Cessna's have them in all planes, even 50-60 years old ones.
The angle of attack is the angle between the chord line of the wing and the oncoming air (or relative wind). This is distinct from what the artificial horizon measures. The artificial horizon is concerned with the aircraft's orientation relative to the gravitational pull of the Earth, indicating whether the nose of the aircraft is above or below the horizon and how much the wings are tilted relative to the horizon.
Artificial horizon is not a reliable indicator of angle of attack.
Artificial horizon is not a reliable indicator of angle of attack.
> Artificial horizon is not a reliable indicator of angle of attack.
Keyword being "reliable", but it is pretty close to it. That's how you get to fly safely through clouds using only an artificial horizon indicator.
Keyword being "reliable", but it is pretty close to it. That's how you get to fly safely through clouds using only an artificial horizon indicator.
I’ve been thinking that now that we have glass cockpits the airspeed indicator could automatically reflect the current stall speed under all conditions. I.e. green arc could shrink in a steep turn, etc.
I concur that this would be an equivalently-useful mechanism to displaying AOA directly.
But we got a nice tea kettle whistle to tell us were about to die.
I've always thought it sounded like a kazoo. Or sometimes a harmonica.
But I like the imagery of a a little tea kettle on a hob under the panel.
But I like the imagery of a a little tea kettle on a hob under the panel.
I'm not a pilot, but now I'm curious. What do you actually do if the plane stalls, or is about to do so? Other than die?
To add to what Toutouxc said, stalls are a fairly routine training/familiarization maneuver in most light aircraft. The typical recovery is just to push forward on the stick/yoke. A manual[0] I found with a web search claims a Cessna 185 on floats may require up to 200 feet to recover.
Stalling one wing but not the other usually results in a spin, for which recovery requires both breaking the stall and stopping the rotation. The ailerons, located near the wingtips are not effective (or even counterproductive) during a spin because air is not flowing smoothly over the stalled wing; the rudder, located on the tail is used to stop the rotation. This usually requires more altitude for recovery.
If you stall one wing but not the other at an altitude of 15 meters (49 feet), it's very likely you're going to contact the surface in a manner you did not intend. Inappropriate control inputs, such as trying to correct the resulting bank using the ailerons guarantee it. It's still a good idea to attempt to recover rather than sit still and pray because a more controlled impact is usually more survivable.
[0] https://aerocet.com/uploads/A-10010.pdf
Stalling one wing but not the other usually results in a spin, for which recovery requires both breaking the stall and stopping the rotation. The ailerons, located near the wingtips are not effective (or even counterproductive) during a spin because air is not flowing smoothly over the stalled wing; the rudder, located on the tail is used to stop the rotation. This usually requires more altitude for recovery.
If you stall one wing but not the other at an altitude of 15 meters (49 feet), it's very likely you're going to contact the surface in a manner you did not intend. Inappropriate control inputs, such as trying to correct the resulting bank using the ailerons guarantee it. It's still a good idea to attempt to recover rather than sit still and pray because a more controlled impact is usually more survivable.
[0] https://aerocet.com/uploads/A-10010.pdf
You decrease the angle of attack, i.e. you let the nose drop a bit. When the stall has fully developed into a spin, you perform the spin recovery procedure for your aircraft. Hopefully you still have some altitude left.
Gentle reminder that it's good practice to define your acronyms at least once, particularly for audiences they may not be SMES.
Non sequitur from non-pilot: I was once in Duluth, MN in the bitter cold and watched a Cessna with skis (for landing on the frozen lakes of the Boundary Waters) land at the airport. It was the utterly bewildering to see how slowly it was going in the air. And how little distance it took to stop. Short Landing Kit I assume. I've seen ducks and geese come into land on lakes at higher speeds!
There are quite a few planes specifically designed for that kind of thing, e.g. https://en.wikipedia.org/wiki/Antonov_An-2:
"According to the operating handbook, the An-2 has no stall speed. A note from the pilot's handbook reads: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h (40 mph) and when the airplane slows to a forward speed of about 40 km/h (25 mph), the airplane will sink at about a parachute descent rate until the aircraft hits the ground." As such, pilots of the An-2 have stated that they are capable of flying the aircraft in full control at 48 km/h (30 mph) ... This slow stall speed makes it possible for the aircraft to fly backwards relative to the ground: if the aircraft is pointed into a headwind of roughly 56 km/h (35 mph), it will travel backwards at 8 km/h (5 mph) whilst under full control."
"According to the operating handbook, the An-2 has no stall speed. A note from the pilot's handbook reads: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h (40 mph) and when the airplane slows to a forward speed of about 40 km/h (25 mph), the airplane will sink at about a parachute descent rate until the aircraft hits the ground." As such, pilots of the An-2 have stated that they are capable of flying the aircraft in full control at 48 km/h (30 mph) ... This slow stall speed makes it possible for the aircraft to fly backwards relative to the ground: if the aircraft is pointed into a headwind of roughly 56 km/h (35 mph), it will travel backwards at 8 km/h (5 mph) whilst under full control."
I once got to ride in an An-2 on a tourist sightseeing flight. I've always remembered the sense that the pilot didn't even bother to line up with the runway ahead of time when landing, but simply took a gentle turn onto it upon reaching it, at roughly the speed of a car.
I'm sure this is a slight exaggeration in my memory, but it really was able to fly incredibly slowly and take turns in an incredibly short distance.
I'm sure this is a slight exaggeration in my memory, but it really was able to fly incredibly slowly and take turns in an incredibly short distance.
You'd think that sort of handling would make for some interesting use cases-- aerial photography for example, maybe some sorts of cropdusting where the slower speed offers more precision.
I wonder if there's anything else built that fits that market today, since I suppose it's a hard-sell to convince Western pilots and businesses to buy Soviet old-stock.
I wonder if there's anything else built that fits that market today, since I suppose it's a hard-sell to convince Western pilots and businesses to buy Soviet old-stock.
An-2 specifically is kinda popular with Western collectors, as far as I know. But if there were still broad applications for this kind of performance, surely we'd see more modern designs along those lines?
For An-2, the ability to perform such tricks wasn't really the goal, just a side effect. The goal was to have a cheap mass-produced utility plane that could take off and land on very rough makeshift airstrips in remote locations, which were plentiful in USSR at the time when it was designed (~1950). These days there's probably way fewer locations like that, and for those that do exist, helicopters provide an adequate solution without the need to design a new dedicated airframe. Note that all those benefits aren't free, either: the downsides of the design include high fuel consumption and high noise levels.
As far as I know, even in Russia, most present-day use of An-2 is for skydiving.
For An-2, the ability to perform such tricks wasn't really the goal, just a side effect. The goal was to have a cheap mass-produced utility plane that could take off and land on very rough makeshift airstrips in remote locations, which were plentiful in USSR at the time when it was designed (~1950). These days there's probably way fewer locations like that, and for those that do exist, helicopters provide an adequate solution without the need to design a new dedicated airframe. Note that all those benefits aren't free, either: the downsides of the design include high fuel consumption and high noise levels.
As far as I know, even in Russia, most present-day use of An-2 is for skydiving.
A certain STOL-modified Piper Cub barely needs a runway longer than a driveway. https://youtu.be/hPakbghLe38
Some of those Cessnas have a stall speed so low they can fly backward on a windy day.
I have been a passenger in a C-170 with a STOL kit that flew backwards over a beach on the Washington coast. We landed well behind where we took off. The takeoff and landing were both nearly vertical. Had a steady wind from the ocean.
You forgot to unfurl the course sails and get out and push.
I'm sure it's happened a few times with unsecured planes in a windstorm.
It would be a neat trick to see a pilot pull that off intentionally and under control.
It would be a neat trick to see a pilot pull that off intentionally and under control.
>“I let it lift off by itself. It was well-trimmed and it lifted off normally by itself.”
It sounds like the pilot wasn't fully prepared and engaged to compensate for propeller torque at the moment the aircraft left the surface of the water. At full takeoff power in a single engine aircraft this can be very intense and jarring, particularly with a high pitch ascent and full prop pitch. All it took was a momentary lapse in keeping the wings level to stall out at that speed.
>The indirect causal factor was the pilot’s lack of experience with stalling the aircraft. He told the investigation that he had never stalled the aircraft, which meant that he was unable to recognise the stall during the take-off.
It's this lack of stick and rudder skills at the root of the incident.
It sounds like the pilot wasn't fully prepared and engaged to compensate for propeller torque at the moment the aircraft left the surface of the water. At full takeoff power in a single engine aircraft this can be very intense and jarring, particularly with a high pitch ascent and full prop pitch. All it took was a momentary lapse in keeping the wings level to stall out at that speed.
>The indirect causal factor was the pilot’s lack of experience with stalling the aircraft. He told the investigation that he had never stalled the aircraft, which meant that he was unable to recognise the stall during the take-off.
It's this lack of stick and rudder skills at the root of the incident.
> The pilot had set the trim so that the aircraft would lift off from the step and begin to climb away. The rudder trim was set almost as far right as it could go. The pilot described the take-off as quick and easy. “I let it lift off by itself. It was well-trimmed and it lifted off normally by itself.”
Further down.
> The maintenance team discovered an incorrect right wing geometric twist, which was unrelated to the hangar roof collapse but probably happened during repairs done previously in the USA. As a result, the aircraft had a tendency to roll and had been uncomfortable to fly because of a lack of aileron trim. This might explain why the pilot had the aircraft trimmed full right rudder on take-off: to correct for this roll.
He may have actually had too much rudder. They don’t say this explicitly, but correcting for roll with rudder means you’ll be cross controlled.
He was dangerously near stall speed without realizing it. Some turbulence could cause a small partial stall.
If the airplane was straight, it would have just dropped the nose a bit and corrected. But with a twist in one wing and 2/3 of rudder trim engaged, it’s more like it entered a snap roll. One wing was stalled, one was still making lift.
The airplane felt fine to the pilot, but it was essentially modified to be a snap roll machine. I don’t think a stock 185 would have even been capable of what happened here.
Further down.
> The maintenance team discovered an incorrect right wing geometric twist, which was unrelated to the hangar roof collapse but probably happened during repairs done previously in the USA. As a result, the aircraft had a tendency to roll and had been uncomfortable to fly because of a lack of aileron trim. This might explain why the pilot had the aircraft trimmed full right rudder on take-off: to correct for this roll.
He may have actually had too much rudder. They don’t say this explicitly, but correcting for roll with rudder means you’ll be cross controlled.
He was dangerously near stall speed without realizing it. Some turbulence could cause a small partial stall.
If the airplane was straight, it would have just dropped the nose a bit and corrected. But with a twist in one wing and 2/3 of rudder trim engaged, it’s more like it entered a snap roll. One wing was stalled, one was still making lift.
The airplane felt fine to the pilot, but it was essentially modified to be a snap roll machine. I don’t think a stock 185 would have even been capable of what happened here.
Kind of my point though. The pilot was disengaged from the controls, and relying on trim settings for takeoff. Regardless of the different roll characteristics, if he had been actively controlling the yoke at the time rather than needing a split second to react and correct, the accident probably would not have occurred.
I really doubt that. He was still “actively controlling” the yoke. This is a back country 185, it’s not like he had the autopilot engaged.
In my experience as a flight instructor, pilots having the airplane trimmed out properly generally only improved control.
In my experience as a flight instructor, pilots having the airplane trimmed out properly generally only improved control.
Note that the twist had been repaired before the accident.
> When they repaired the damage to the right wing, they also corrected the geometric twist, removing the aircraft’s tendency to roll.
However, since the repairs were completed five days before the accident, the pilot may have set the rudder based on pre-repair experience with the plane. He may not have been informed of the change in twist, or may not have understood it.
> When they repaired the damage to the right wing, they also corrected the geometric twist, removing the aircraft’s tendency to roll.
However, since the repairs were completed five days before the accident, the pilot may have set the rudder based on pre-repair experience with the plane. He may not have been informed of the change in twist, or may not have understood it.
Just so we're clear, there's practically no such thing as an "unstallable plane". If some pilot believes that then their license should be revoked. Even jet engines can experience stalls internally on the compressor blades, and even helicopters can experience stalls on their retreating blade. I would compare it to someone believing that their car cannot possibly lose traction.
Exceptions, which of course must exist, include some fly-by-wire setups which limit the actuation of flight surfaces so that it should be theoretically impossible to put an aircraft in that situation, and rumored properties of some abnormal constructions like the An-2. Although even there you should repeatedly get comfortable with what happens in/around a stall, at least in simulators.
The fact that air started to separate and the end of the wing, and not at the root, is scary. It means the pilot wouldn't get the normal warning in the form of airframe shaking. Bad modification.
Exceptions, which of course must exist, include some fly-by-wire setups which limit the actuation of flight surfaces so that it should be theoretically impossible to put an aircraft in that situation, and rumored properties of some abnormal constructions like the An-2. Although even there you should repeatedly get comfortable with what happens in/around a stall, at least in simulators.
The fact that air started to separate and the end of the wing, and not at the root, is scary. It means the pilot wouldn't get the normal warning in the form of airframe shaking. Bad modification.
Canard aircraft, for example, stall the canard first, resulting in the nose dropping, preventing the main wing from ever stalling.
The main wing can still be stalled in a canard; it’s not easy but it is possible and when it happens it’s almost unrecoverable because the canard will be stalled too and no flying surfaces will have sufficient lift to correct the condition. It’s a condition called “deep stall”
IIRC non-canard aircraft can have this happen when the stall causes the plane to fall at an angle where the wake turbulence of the wings covers the elevators.
Usually in a cross-controlled “slip” where the fuselage is held at a fairly dramatic angle relative to the slipstream (relative wind) and the fuselage “blanks out” one side of the main wing.
This is far from universally true. The Saab 37 Viggen fighter jet (which was also the first series produced canard aircraft) is capable of departing from controlled flight into a stalled attitude in no less than five different ways, according to its flight manual:
> If the angle of attack exceeds the permitted limits, some yaw disturbances appear around alpha 25-28°, and at alpha 28-30° there are weak pitch-up tendencies. If the stick is moved forward to counter the pitch-up, the aircraft returns to normal alpha, possibly after overshooting up to alpha ~50°. Note that the angle of attack instrument only shows the area -4° to +26°.
> If the stick movement forward at the pitch-up is too small or is made too late, such that the angle of attack does not immediately decrease, the aircraft departs into superstall or spin. If the pitch-up occurs without aileron input, the departure usually results in superstall. If the pitch-up occurs with any aileron input active, the aircraft is affected by adverse yaw and the likelihood of a spin increases.
In addition to the superstall, the aircraft has two spin modes, in the flight manual referred to as flat and oscillating. The difference is basically the rotation speed and if there are oscillations in pitch and/or roll or not. The recovery is pretty conventional:
> In superstall or spin the pitch authority is good, which eases recovery. Aileron input results in adverse yaw, that is to say rolling right gives a yaw to the left and vice versa. Rudder authority is negligible.
> Recovery from superstall and oscillating spin is accomplished by moving the stick to a position somewhat forward of the neutral pitch position, with ailerons and rudder neutral. To recover from a flat spin, the yawing rotation must be stopped first, which is accomplished with neutral pitch and full roll input in the direction of the rotation ("stick into the spin"). When the rotation has just about ceased, recovery is accomplished with neutral ailerons and the stick somewhat forward of neutral, just like when recovering from superstall and oscillating spin.
In addition to regular stalled attitudes though, the aircraft also exhibits another stalled attitude with autorotation, the "plunging spiral" (sv. störtspiral) which can also be encountered in two variants. I'm honestly not sure how exactly it works aerodynamically. The flight manual says:
> In certain adverse dynamic scenarios, the aircraft can enter an uncontrolled attitude of the autorotating type, here called plunging spiral . The plunging spiral, which can be either right side up or inverted, is considered to be the potentially most dangerous form of uncontrolled flight that has been discovered during the spin tests of aircraft 37.
> The most common form of the plunging spiral is the inverted one. The following attitudes/maneuvers repeatably result in an inverted plunging spiral: 1) somersault into inverted position from oscillating spin (for example while attempting to recover from a spin with the stick fully forward), 2) stalling the tailfin through so-called "knife edge flying". The inverted plunging spiral is characterized by: 1) negative load factor (-1 to -3 G) 2), low nose, 3) very high rate of rotation in the roll axis (≥ 200°/s), 4) high sink rate (≥ 150 m/s).
> Moving the stick back and/or aileron input to either side tends to increase the rate of the roll rotation. The rotation can be stopped by moving the stick fully forward with no aileron input. When the rotation has ceased, the stick is moved back to neutral pitch, and the aircraft recovers to controlled flight.
> The aircraft only departed into a non-inverted plunging spiral on a few occasions during the spin tests. It has not been possible to define any repeatable attitude or maneuver that results in a non-inverted plunging spiral. During the spin tests the non-inverted plunging spiral only occurred on the following two occasions (not repeatable): 1) when recovering from an inverted superstall, 2) when recovering from an oscillating non-inverted spin. The non-inverted plunging spiral is characterized by: 1) positive load factor (+1 to +3 G), 2) low nose, 3) very high rate of rotation in the roll axis (≥ 200°/s), 4) high sink rate (≥ 150 m/s).
> In a non-inverted plunging spiral, aileron inputs have no effect. Instead, the roll rotation must be stopped by pulling gently back on the stick until the rotation ceases. When the rotation has ceased, the stick is moved forward to the neutral pitch position and the aircraft recovers into controlled flight.
> If the angle of attack exceeds the permitted limits, some yaw disturbances appear around alpha 25-28°, and at alpha 28-30° there are weak pitch-up tendencies. If the stick is moved forward to counter the pitch-up, the aircraft returns to normal alpha, possibly after overshooting up to alpha ~50°. Note that the angle of attack instrument only shows the area -4° to +26°.
> If the stick movement forward at the pitch-up is too small or is made too late, such that the angle of attack does not immediately decrease, the aircraft departs into superstall or spin. If the pitch-up occurs without aileron input, the departure usually results in superstall. If the pitch-up occurs with any aileron input active, the aircraft is affected by adverse yaw and the likelihood of a spin increases.
In addition to the superstall, the aircraft has two spin modes, in the flight manual referred to as flat and oscillating. The difference is basically the rotation speed and if there are oscillations in pitch and/or roll or not. The recovery is pretty conventional:
> In superstall or spin the pitch authority is good, which eases recovery. Aileron input results in adverse yaw, that is to say rolling right gives a yaw to the left and vice versa. Rudder authority is negligible.
> Recovery from superstall and oscillating spin is accomplished by moving the stick to a position somewhat forward of the neutral pitch position, with ailerons and rudder neutral. To recover from a flat spin, the yawing rotation must be stopped first, which is accomplished with neutral pitch and full roll input in the direction of the rotation ("stick into the spin"). When the rotation has just about ceased, recovery is accomplished with neutral ailerons and the stick somewhat forward of neutral, just like when recovering from superstall and oscillating spin.
In addition to regular stalled attitudes though, the aircraft also exhibits another stalled attitude with autorotation, the "plunging spiral" (sv. störtspiral) which can also be encountered in two variants. I'm honestly not sure how exactly it works aerodynamically. The flight manual says:
> In certain adverse dynamic scenarios, the aircraft can enter an uncontrolled attitude of the autorotating type, here called plunging spiral . The plunging spiral, which can be either right side up or inverted, is considered to be the potentially most dangerous form of uncontrolled flight that has been discovered during the spin tests of aircraft 37.
> The most common form of the plunging spiral is the inverted one. The following attitudes/maneuvers repeatably result in an inverted plunging spiral: 1) somersault into inverted position from oscillating spin (for example while attempting to recover from a spin with the stick fully forward), 2) stalling the tailfin through so-called "knife edge flying". The inverted plunging spiral is characterized by: 1) negative load factor (-1 to -3 G) 2), low nose, 3) very high rate of rotation in the roll axis (≥ 200°/s), 4) high sink rate (≥ 150 m/s).
> Moving the stick back and/or aileron input to either side tends to increase the rate of the roll rotation. The rotation can be stopped by moving the stick fully forward with no aileron input. When the rotation has ceased, the stick is moved back to neutral pitch, and the aircraft recovers to controlled flight.
> The aircraft only departed into a non-inverted plunging spiral on a few occasions during the spin tests. It has not been possible to define any repeatable attitude or maneuver that results in a non-inverted plunging spiral. During the spin tests the non-inverted plunging spiral only occurred on the following two occasions (not repeatable): 1) when recovering from an inverted superstall, 2) when recovering from an oscillating non-inverted spin. The non-inverted plunging spiral is characterized by: 1) positive load factor (+1 to +3 G), 2) low nose, 3) very high rate of rotation in the roll axis (≥ 200°/s), 4) high sink rate (≥ 150 m/s).
> In a non-inverted plunging spiral, aileron inputs have no effect. Instead, the roll rotation must be stopped by pulling gently back on the stick until the rotation ceases. When the rotation has ceased, the stick is moved forward to the neutral pitch position and the aircraft recovers into controlled flight.
Very bad modification. And wrong (but natural) response from the pilot trying to pick up the dropping wing with aileron input. That would have made the asymmetric stall worse.
Edit: It seems that I completely misread what Wikipedia said, disregard this comment.
Over 18k An-2 were produced during the time of 1947-2001. It’s an unusual plane due how old it is and that many are still in operation so general stats should take that into account. It’s well known for being nearly impossible to stall with a stall speed of 30 knots - if it does stall it’ll sink at the rate of a parachute which is still faster than you’d want to hit the ground for a landing. It’s also easy to pick up that speed by dipping the nose. If someone crashes an an-2 by stalling it they had to really work hard to do it. Any pilot that did this would be considered unsafely inept to an almost unimaginable degree.
This article is the first I'm hearing of a Cessna 185 being considered unstallable and I do wonder it that title was picked for engagement. Float planes are extra dangerous with more that can go wrong and less margins for safety.
This article is the first I'm hearing of a Cessna 185 being considered unstallable and I do wonder it that title was picked for engagement. Float planes are extra dangerous with more that can go wrong and less margins for safety.
Wasn't AN-2 the plane where the manual advises that if you need to land and cannot see your landing site, you should fly low and slow and intentionally stall the plane?
I don't know but that would make sense, landing at the speed of a parachute is better than crashing. Not sure on the exact numbers but a parachute sink rate of 5m/s is over the usual landing touch down sink rate of 1m/s. I would guess at that rate there might still be some damage to crew and airframe. If done skillfully I would image it would be possible to trade some forward speed for a slower sink rate right before touchdown to make for much softer landing.
https://aviation.stackexchange.com/questions/65718/what-make...
There are many ways of totalling a plane beyond a stall.
There are many ways of totalling a plane beyond a stall.
So many factors that could be blamed in this story. As in every other aircraft accident. But EVERY plane will stall.
THERE IS NO SUCH THING AS AN 'UNSTALLABLE' PLANE.
I once overloaded a plane inadvertently, by having a heavy load plus a full weight of fuel.
At the point of lift-off, the stall-warning started screaming at me as I started to go into the climb. Training kicked in and I pushed the nose down to maintain flying speed. Practically no climb at all possible though. I did a very quick and low circuit, landed and offloaded.
Funny how those little tense moments stay with you for ever. :)
THERE IS NO SUCH THING AS AN 'UNSTALLABLE' PLANE.
I once overloaded a plane inadvertently, by having a heavy load plus a full weight of fuel.
At the point of lift-off, the stall-warning started screaming at me as I started to go into the climb. Training kicked in and I pushed the nose down to maintain flying speed. Practically no climb at all possible though. I did a very quick and low circuit, landed and offloaded.
Funny how those little tense moments stay with you for ever. :)
EVERY? Is a plane with a thrust-to-weight ratio over 1 able to stall at full throttle?
A stall is a loss of lift from an aerofoil due to a high Angle of Attack causing a separation of the airflow from the
aerofoil. No laminar flow = no lift.
There is such an animal as a high-speed stall, where the angle of attack is greater than 15 degrees. Can happen when a gung-ho pilot makes a high speed dive over his girl-friends house and leaves it too late and too low to pull out gently.
('Gently' being a pull back on the controls such that the Angle of Attack is less than 15 degrees, and curves enough to pull smoothly out of the dive, go into a climb and away to safety.)
He pulls back too hard on the controls. The angle of attack goes over 15 degrees, there is no 'lift' to stop the dive, and the plane continues the trajectory straight into the girl-friend's house.
Whether that has ever actually happened, I do not know. But that was the warning not to be a smart-arse as told to me by my CFI.
There is such an animal as a high-speed stall, where the angle of attack is greater than 15 degrees. Can happen when a gung-ho pilot makes a high speed dive over his girl-friends house and leaves it too late and too low to pull out gently.
('Gently' being a pull back on the controls such that the Angle of Attack is less than 15 degrees, and curves enough to pull smoothly out of the dive, go into a climb and away to safety.)
He pulls back too hard on the controls. The angle of attack goes over 15 degrees, there is no 'lift' to stop the dive, and the plane continues the trajectory straight into the girl-friend's house.
Whether that has ever actually happened, I do not know. But that was the warning not to be a smart-arse as told to me by my CFI.
Yes
Life jackets seem like they’d be problematic in an enclosed cabin where their use is if you’ve crashed and are taking on water. That’s a bit different compared to a pleasure craft or other vessel that has an outside deck and likely more time to react.
But I don’t really know things. Perhaps most float plane emergencies that require life jackets don’t suffer from my perception of the issue.
But I don’t really know things. Perhaps most float plane emergencies that require life jackets don’t suffer from my perception of the issue.
Indeed, passengers inflating their life jackets too early directly caused many of the deaths on Ethiopian Airlines Flight 961 [0]. This is why the modern safety briefing includes the bit about waiting until you've exited the cabin to inflate your life jacket.
I have no clue how this applies to floatplanes, though—I'm curious for more details about when the article says "there are approved life jackets which could be used to deal with these circumstances".
[0] https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961
I have no clue how this applies to floatplanes, though—I'm curious for more details about when the article says "there are approved life jackets which could be used to deal with these circumstances".
[0] https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961
> I'm curious for more details about when the article says "there are approved life jackets which could be used to deal with these circumstances"
In context, that says:
“Floating and automatically operating life jackets aren’t practical, specifically because of cases like this where the occupants have to dive out of the capsized aircraft in order to escape the cabin. However, there are approved life jackets which could be used to deal with these circumstances.”
So, I guess there are approved life jackets that do not automatically inflate and are neutrally buoyant, thus minimally hindering attempts to leave a submerged plane while wearing one.
In context, that says:
“Floating and automatically operating life jackets aren’t practical, specifically because of cases like this where the occupants have to dive out of the capsized aircraft in order to escape the cabin. However, there are approved life jackets which could be used to deal with these circumstances.”
So, I guess there are approved life jackets that do not automatically inflate and are neutrally buoyant, thus minimally hindering attempts to leave a submerged plane while wearing one.
Yeah, I guess my main confusion is whether that means a normal (uninflated) airliner life jacket that you're just required to put on pre-emptively, or something more specialized.
"Many of the passengers survived the initial crash, but they had disregarded, did not understand, or did not hear Leul's warning not to inflate their life jackets inside the aircraft, causing them to be pushed against the ceiling of the fuselage by the inflated life jackets when water flooded in. Unable to escape, they drowned."
That seems strange to me. Why would they not simply take off the life jacket and swim out?
The inflatable ones are often designed to be impossible to remove… at least not easily. They inflate into a thing that’s kind of gently choking you.
Definitely far up the list on horrible ways to die.
In my vernacular, I distinguish between "life jackets" and "buoyancy aids". Apparently most people don't.
A buoyancy aid has a foam core, and always provides buoyancy. It's the sort of thing you'd wear while kayaking, but it's far too bulky to want to wear it unless you expect to go in the water.
A life jacket is inflatable, and normally automatic. If you're at risk of falling in, and to do so would be dangerous, you should probably wear one of these -- if you go in the water, it'll inflate automatically. This isn't suitable if you might get wet without wanting the life jacket to inflate, though, and you can get equivalents with manual inflation. The ones you get on aircraft are cheaper than ones you're expected to re-use by wearing multiple times but in neither case will you inflate it multiple times.
The downside of a manually-inflated life-jacket is that you need to be conscious to inflate it. The downside of an automatic life-jacket is that if you get wet, it'll inflate. The downside of the buoyancy aid is that it's always bulky, but on the other hand if you're wearing it, it'll always work.
A buoyancy aid has a foam core, and always provides buoyancy. It's the sort of thing you'd wear while kayaking, but it's far too bulky to want to wear it unless you expect to go in the water.
A life jacket is inflatable, and normally automatic. If you're at risk of falling in, and to do so would be dangerous, you should probably wear one of these -- if you go in the water, it'll inflate automatically. This isn't suitable if you might get wet without wanting the life jacket to inflate, though, and you can get equivalents with manual inflation. The ones you get on aircraft are cheaper than ones you're expected to re-use by wearing multiple times but in neither case will you inflate it multiple times.
The downside of a manually-inflated life-jacket is that you need to be conscious to inflate it. The downside of an automatic life-jacket is that if you get wet, it'll inflate. The downside of the buoyancy aid is that it's always bulky, but on the other hand if you're wearing it, it'll always work.
Which vernacular is that?
In boating a life jacket does not need to be inflatable. https://uscgboating.org/recreational-boaters/life-jacket-wea... says:
> There are four basic design types: Inherent, Inflatable, Hybrid, and Special Purpose.
> There are two main classes of PFDs.
> * Those which provide face up in-water support to the user regardless of physical conditions (lifejackets).
> * Those which require the user to make swimming and other postural movements to position the user with the face out of the water (buoyancy aid).
It mentions both "Foam filled lifejackets" and "Inflatable lifejackets".
In boating a life jacket does not need to be inflatable. https://uscgboating.org/recreational-boaters/life-jacket-wea... says:
> There are four basic design types: Inherent, Inflatable, Hybrid, and Special Purpose.
> There are two main classes of PFDs.
> * Those which provide face up in-water support to the user regardless of physical conditions (lifejackets).
> * Those which require the user to make swimming and other postural movements to position the user with the face out of the water (buoyancy aid).
It mentions both "Foam filled lifejackets" and "Inflatable lifejackets".
Seems like it's maybe a UK thing, and my (fairly limited) water-sports experience is kayaking and small sailboats.
Isn't the English language fun?
Isn't the English language fun?
Interesting! I checked out what the RNLI had to say at https://rnli.org/safety/lifejackets and that page only mentions lifejackets along with gas.
However, if you "Download our lifejackets and buoyancy aids guide as a PDF (3.48MB)" at https://rnli.org/-/media/rnli/downloads/1983319_choose_it_we... you'll read "Children’s lifejackets may rely on foam, air and foam, or CO2 only to provide buoyancy" and "Air and foam or CO2 lifejackets meet the requirements of a level 150 lifejacket and are suitable for offshore use. Normally, foam lifejackets provide level 100 buoyancy and are suitable for inshore use."
A further search of the RNLI site finds https://rnli.org/magazine/magazine-featured-list/2018/june/t... with "The foam-based Beaufort lifejacket [of the 1970s] upped the buoyancy level, allowing a crew member to also support the person being rescued." but by the 1990s "The bulkier gear of all-weather lifeboat crews meant they needed a more compact lifejacket, which inflated automatically on hitting the water using a built-in gas canister."
Since I learned my small watercraft skills in the warm waters of Florida, instead of chilly UK, I can see how that would make a difference.
However, if you "Download our lifejackets and buoyancy aids guide as a PDF (3.48MB)" at https://rnli.org/-/media/rnli/downloads/1983319_choose_it_we... you'll read "Children’s lifejackets may rely on foam, air and foam, or CO2 only to provide buoyancy" and "Air and foam or CO2 lifejackets meet the requirements of a level 150 lifejacket and are suitable for offshore use. Normally, foam lifejackets provide level 100 buoyancy and are suitable for inshore use."
A further search of the RNLI site finds https://rnli.org/magazine/magazine-featured-list/2018/june/t... with "The foam-based Beaufort lifejacket [of the 1970s] upped the buoyancy level, allowing a crew member to also support the person being rescued." but by the 1990s "The bulkier gear of all-weather lifeboat crews meant they needed a more compact lifejacket, which inflated automatically on hitting the water using a built-in gas canister."
Since I learned my small watercraft skills in the warm waters of Florida, instead of chilly UK, I can see how that would make a difference.
I’ve heard that distinction used in the UK.
The other down side of buoyancy aids I was told about is that many (most?) will not turn you face up if you are unconscious. Gives useful extra mobility for sports but can be fatal if the wearer is unconscious.
The other down side of buoyancy aids I was told about is that many (most?) will not turn you face up if you are unconscious. Gives useful extra mobility for sports but can be fatal if the wearer is unconscious.
It depends on the design of the specific device. A buoyancy aid with a foam collar will do it, but is less comfortable to wear. With an inflatable life jacket, to collar is not noticeable until it inflates.
It sounds like the two surviving passengers would have died if they had life jackets on. I can’t imagine getting out of an inverted, flooded 185 cabin with a life jacket on.
I think there was some sense to not requiring life jackets on seaplanes. They’re much more confined spaces than most pleasure boats, not to mention that you’re usually on a boat rather than in it. The flooding is also usually just about instant as the airplane rolls over.
Seems common for reactive legislation to not actually fix the situation that’s being reacted to. Requiring shoulder harnesses during takeoff and landing (which is the case in the US) would have actually kept the deceased passenger conscious to escape, as said in the report. But they didn’t change that law.
I think there was some sense to not requiring life jackets on seaplanes. They’re much more confined spaces than most pleasure boats, not to mention that you’re usually on a boat rather than in it. The flooding is also usually just about instant as the airplane rolls over.
Seems common for reactive legislation to not actually fix the situation that’s being reacted to. Requiring shoulder harnesses during takeoff and landing (which is the case in the US) would have actually kept the deceased passenger conscious to escape, as said in the report. But they didn’t change that law.
My reflex is to never mandate safety procedures. To put it simply, why should the state use force to mandate something like safety. The implication being if someone refuses the force of the state is used on them… which is definitely not good or improving safety.
Mandating the seatbelts exist, sure. Mandating people wear them? Idk about that.
In the case of tractors for instance, wearing a seatbelt is downright dangerous. You cannot jump out then, and will be killed by a tractor if it flips.
Mandating the seatbelts exist, sure. Mandating people wear them? Idk about that.
In the case of tractors for instance, wearing a seatbelt is downright dangerous. You cannot jump out then, and will be killed by a tractor if it flips.
> In the case of tractors for instance, wearing a seatbelt is downright dangerous. You cannot jump out then, and will be killed by a tractor if it flips.
The "proper" solution would be to have a rollcage so that even a flipped tractor does not crush its occupants. Not having a roll cage (presumably to save $) is a result of weaker/less mandated safety procedures already. Cars have a roof crush test. The solution isn't "jump out when big machine starts tipping", it's "protect the humans in the machine".
[0] - https://www.consumerreports.org/cro/2012/02/rollover-101/ind...
The "proper" solution would be to have a rollcage so that even a flipped tractor does not crush its occupants. Not having a roll cage (presumably to save $) is a result of weaker/less mandated safety procedures already. Cars have a roof crush test. The solution isn't "jump out when big machine starts tipping", it's "protect the humans in the machine".
[0] - https://www.consumerreports.org/cro/2012/02/rollover-101/ind...
I believe that Rollover Protection Systems (ROPS) have been mandatory on new tractors up to a certain weight for quite some time now.
Everyone ends up paying for that, in the form of insurance rates.
Not only that but I think there’s also a meaningful quality to living in a society with excessive avoidable deaths. I personally think it contributes to a “shields up, guard up” culture that I’ve experienced and found exhausting.
And healthcare insurance if you live in the US, and regardless of where you live it clogs up your entire healthcare system as Jimmy-no-seatbelt flies into the trauma center.
In countries with universal healthcare you pay too, it's just called "taxes" instead.
That's an argument against a state-run healthcare system. It gives the state reason to classify arbitrary things as "increases the cost of insurance" and prohibit them.
They could just not cover injuries where a seatbelt isn’t warn.
That said, we have evidence that seatbelt wearing didn’t impact insurance rates. Literally look at the rates over time, even after these laws were enacting, insurance rates rose fast as ever
That said, we have evidence that seatbelt wearing didn’t impact insurance rates. Literally look at the rates over time, even after these laws were enacting, insurance rates rose fast as ever
That's not how emergency room care works. It doesn't matter whether it's covered or not, you're going to get treated; quite likely the hospital ends up eating the bill if insurance doesn't pay.
It's not just you and your passengers that are less safe when you drive without seatbelts.
If you have to make a sudden sharp swerve when driving centrifugal forces try to move you from in front of the steering wheel, which can make it harder for you to remain in control. That increases the danger to nearby vehicles and pedestrians (and to nearby property that you might hit).
Seat and shoulder belts help keep you in place in front of the steering wheel.
If you have to make a sudden sharp swerve when driving centrifugal forces try to move you from in front of the steering wheel, which can make it harder for you to remain in control. That increases the danger to nearby vehicles and pedestrians (and to nearby property that you might hit).
Seat and shoulder belts help keep you in place in front of the steering wheel.
Mandating the wearing of seatbelts isn’t entirely about protecting the person wearing the seatbelt. An unbelted occupant becomes a projectile in a sufficiently violent collision, and that projectile can cause harm to people outside of the vehicle.
Heck, I recently saw a video (may be an old one) of a driver who fell out of his car while showing off his acceleration. Now the entire car is an uncontrolled projectile.
Interesting that pleasure craft have dead-man switches you can optionally affix. They’re also designed to turn anti-clockwise forever if nobody is at the wheel.
I guess because there aren’t seatbelts and these boats are usually open-top.
I guess because there aren’t seatbelts and these boats are usually open-top.
Isn't this dangerous to the person falling off (assuming no dead-man switch)? You fall off only to be run over by your own craft one turn later... It does mean that the boat won't run away far though, so there's that.
> pleasure craft... turn anti-clockwise forever if nobody is at the wheel.
That's probably a result of the "paddle wheel" effect of the propellor rotating through the water: a bug not a feature.
That's probably a result of the "paddle wheel" effect of the propellor rotating through the water: a bug not a feature.
Or harm to other people inside the vehicle.
What a horrible click-bait title. There is nothing about a C185 or one modified with a STOL kit that is unstallable. A better title would be something like "Clueless pilot stalls aircraft. Which unfortunately is not an uncommon thing.
I wonder if they're practicing modern journalism strategies that are worried about libel suits? Or it's so obviously satire to them that they don't need to clarify? When they write:
> However, the investigation discovered that despite his experience, he had never practised stall recovery on the Cessna 185. The pilot had no knowledge of the aircraft’s stall behaviour at all. His opinion was that the Cessna 185 simply didn’t stall.
In writing targeted at lay readers, I would expect this to be followed with something like "This opinion, of course, is complete lunacy. All aircraft can stall. Practicing stall recovery should be a normal part of pilot training."
> However, the investigation discovered that despite his experience, he had never practised stall recovery on the Cessna 185. The pilot had no knowledge of the aircraft’s stall behaviour at all. His opinion was that the Cessna 185 simply didn’t stall.
In writing targeted at lay readers, I would expect this to be followed with something like "This opinion, of course, is complete lunacy. All aircraft can stall. Practicing stall recovery should be a normal part of pilot training."
I believe this article doesn't need such clarifications. It says in unambiguous terms that Cessna had stalled, with an obvious logical implication that a pilot was dead wrong. The article even discusses differences of how the stall occurs in modified and unmodified versions of a plane. To not get the message a reader must be not a lay person, but an exceptionally dumb one.
It was the pilot who believed this Cessna "never stalled". And so he did not recognize and had no idea what to do when it did.
> It is common for flight operations in the wilderness to have the take-off weight close to the maximum.
It is common for the majority of flights in general to have take-off weight close to the maximum, not just bush flying.
The same goes for the remark that "center or gravity was close to the forward limit", that sounds like a risk but it is not. If it's exactly at the limit, that's fine and perfectly safe to fly. If it's over the limit, it's illegal to fly.
It is common for the majority of flights in general to have take-off weight close to the maximum, not just bush flying.
The same goes for the remark that "center or gravity was close to the forward limit", that sounds like a risk but it is not. If it's exactly at the limit, that's fine and perfectly safe to fly. If it's over the limit, it's illegal to fly.
It is not uncommon for flight operations in the wilderness to be up to 15% heavier than the certified maximum limit, and still be perfectly legal. Relevant regulation: 14 CFR § 91.323 - https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F...
Interesting, tnx. We don't have such a general exception in EASA. Only possible with a special permit and a lot of paperwork for a ferry flight or similar.
It's magical how the airframe gets 15% stronger just by arriving in Alaska!
Stick and Rudder (Wolfgang Langewiesche 1972):
> There are situations in flying when he who "ducks," he who flinches, is lost. The most important example is the recovery from a stall at low altitude-getting that stick forward and pointing the nose at the ground; that does require courage, and no two ways about it. [...] It might seem that learning to fly the conventional airplane must necessarily be mostly a matter of drill, like animal training, like making a dog not eat when he wants to eat, making him jump through a flaming hoop when he does not want to jump. [...] But another view of the problem is also possible. It may be that our common sense, our natural reactions mislead us simply because they are working on the basis of wrong ideas in our minds concerning the wing and how it really flies, the controls and what they really do. [...] Perhaps what happens when the beginner reacts wrongly in an airplane is similar to what happened in the early days of the automobile, when a man trying to stop in an emergency would pull back on the wheel as if he had reins in his hands and would even yell "Whoa." There was nothing really wrong with his reactions, with his intentions; the only thing wrong was the image in his head that made him see the automobile as a sort of mechanized horse, to be controlled as horses are controlled. Had he clearly seen in his mind's eye the mechanical arrangement we take for granted now-the clutch that can disconnect the motor, the brakes that can clamp down on the wheels; had he clearly appreciated that the thing was a machine and had no soul at all, not even a horse's soul, and that thus there was no use in speaking to it-he would then have done the right thing without difficulty. It may be that, if we could only understand the wing clearly enough, see its working vividly enough, it would no longer seem to behave contrary to common sense; we should then expect it to behave as it does behave. We could then simply follow our impulses and "instincts." Flying is done largely with one's imagination! If one's images of the airplane are correct, one's behavior in the airplane will quite naturally and effortlessly also be correct.
> There are situations in flying when he who "ducks," he who flinches, is lost. The most important example is the recovery from a stall at low altitude-getting that stick forward and pointing the nose at the ground; that does require courage, and no two ways about it. [...] It might seem that learning to fly the conventional airplane must necessarily be mostly a matter of drill, like animal training, like making a dog not eat when he wants to eat, making him jump through a flaming hoop when he does not want to jump. [...] But another view of the problem is also possible. It may be that our common sense, our natural reactions mislead us simply because they are working on the basis of wrong ideas in our minds concerning the wing and how it really flies, the controls and what they really do. [...] Perhaps what happens when the beginner reacts wrongly in an airplane is similar to what happened in the early days of the automobile, when a man trying to stop in an emergency would pull back on the wheel as if he had reins in his hands and would even yell "Whoa." There was nothing really wrong with his reactions, with his intentions; the only thing wrong was the image in his head that made him see the automobile as a sort of mechanized horse, to be controlled as horses are controlled. Had he clearly seen in his mind's eye the mechanical arrangement we take for granted now-the clutch that can disconnect the motor, the brakes that can clamp down on the wheels; had he clearly appreciated that the thing was a machine and had no soul at all, not even a horse's soul, and that thus there was no use in speaking to it-he would then have done the right thing without difficulty. It may be that, if we could only understand the wing clearly enough, see its working vividly enough, it would no longer seem to behave contrary to common sense; we should then expect it to behave as it does behave. We could then simply follow our impulses and "instincts." Flying is done largely with one's imagination! If one's images of the airplane are correct, one's behavior in the airplane will quite naturally and effortlessly also be correct.
The report of the investigation:
https://turvallisuustutkinta.fi/material/attachments/otkes/t...
https://turvallisuustutkinta.fi/material/attachments/otkes/t...
It's amazing how much work they've put into creating this quite unique configuration just to find out the stall behaviour.
I believe it is normal for flight incidents investigations. I read a lot of Kyra Dempsey writings[1] on accidents and there is a lot of examples of a detailed investigations probing all possible hypotheses even those which are not very probable. They need to know for sure.
[1] https://admiralcloudberg.medium.com/
[1] https://admiralcloudberg.medium.com/
"As a result, the aircraft pitches up unless the pilot controls the flight path using the elevator. If this pitch up is not controlled, the aircraft is at risk of exceeding the stall angle of attack."
This has been happening for me in MSFS, and I considered it a really weird behavior - why can't I take off in a same way as from the runway? Now I know.
This has been happening for me in MSFS, and I considered it a really weird behavior - why can't I take off in a same way as from the runway? Now I know.
As an amateur sailor, the idea that they discussed wearing lifejackets INSIDE the craft seems completely stupid. One of first things any sailor learns is that you do not wear lifejackets inside the craft.
It is not possible to swim through submerged openings (windows, doors) in a lifejackets as it is simply pulling you up and preventing you from diving down.
A lifejacket is also very bulky and offers a lot of opportunity for snagging on equipment.
If they had lifejackets on, probably nobody would save themselves unless they were able to untie themselves in time.
Just imagine the hell of trying to free yourself from the snagged seat belt WHILE in a life jacket that constricts all your movements and makes reaching your legs very difficult and pulls you constantly up putting continuous force on whatever snagged on your feet.
It is not possible to swim through submerged openings (windows, doors) in a lifejackets as it is simply pulling you up and preventing you from diving down.
A lifejacket is also very bulky and offers a lot of opportunity for snagging on equipment.
If they had lifejackets on, probably nobody would save themselves unless they were able to untie themselves in time.
Just imagine the hell of trying to free yourself from the snagged seat belt WHILE in a life jacket that constricts all your movements and makes reaching your legs very difficult and pulls you constantly up putting continuous force on whatever snagged on your feet.
The mindset of that pilot inherently dangerous and complacent. A friend of mine was a casual GA pilot in college. He was constantly practicing failure modes and making contingency plans such as engine failure at different points of takeoff and practicing stall recovery at various speeds, altitudes, bank angles, and AoAs.
I've been involved in general aviation since the late 1970s, currently commercial/twin/instrument rated, have a degree in aerospace engineering, and do what my username says for a living. So I know airplanes, and why they do the things they do. But an appreciation for what is physically occurring during a stall, how the resulting balance of forces influence the aircraft handling during a stall and recovery, and why the recovery must be handled in a specific sequence to avoid overstressing the airplane or losing directional control, are not intuitive and have never been a very strong point among pilots, or even instructors. As a result, you have poorly educated instructors passing along old folk tales to new pilots, who then take them as gospel.
This has been exacerbated over the years by the segregation of the pilot population into two separate groups, who often receive training that stresses different objectives.
Part 141 flight schools are the typical staring point for airline pilots. In these schools, even when flying little Pipers and Cessnas, stall avoidance is the primary method which is taught. Pilots are instructed to initiate a "stall recovery" at the "first indication of stall", which is taught to be stall warning horn indicator sound happening. The goal is to recover with no loss of altitude, and the technique is to add power to power out of the indicated stall immediately upon hearing the stall warning indicator, and use the elevator to keep the airplane at the same altitude. The problem is that the stall warning horn indicator typical starts sounding about 5 knots in advance of a fully developed stall when flying more or less straight and level. So these pilots never experience a fully developed stall, just an approach-to-stall, and often develop an extreme fear of entering an actual stall. This recovery technique also only works in an airliner in the case of an approach-to-stall or at most a very shallow stall. To recover an airliner from a fully developed stall, you must use the same techniques as you do in a Cessna 172, which is to drop the nose to lower the angle of attach and trade some altitude in for airspeed. This was vividly demonstrated by the five co-captains of Air France Flight 447, who tried to power their way out of a fully developed stall, that could have been easily recovered from by a typical student pilot using Cessna techniques.
I learned to fly in a Part 61 school, which typically are things like flying clubs and independent flight instructors teaching people who mostly fly for fun, or for light commercial use like charters, and will be mostly flying light propeller aircraft. In this environment, the aircraft have a much lower power to weight ratio, you cannot power your way out of even an approach-to-stall. Instead of stall avoidance, stall entry, recovery, and exit is taught. Instead of the goal being to minimizing altitude loss, maximizing aircraft control is taught. The goal is to prevent a poorly-handled stall from developing into a spin, which will usually result in a fatal accident like this one did. So if you learned in a Part 61 school, instead of starting recovery as soon as you heard the stall horn, you kept going until a full stall, and the expectation is that the student would say "STALL" when they identified that the airplane had entered a fully developed stall, based on changes in the handling characteristics and sudden drop in altitude. The student would then initiate a recovery by pushing the nose down to reduce the angle of attack, smoothly adding power and right rudder at the same time to add airspeed and counteract for yaw, and then recover from the resulting shallow dive with no more than 200' loss of altitude, but keeping the airplane under perfect directional control. So in part 61 schools, instead of recovering as soon as you heard the horn blip, you spent a lot of time with it going off in your ear. In fact my instructor used to pull the circuit breaker for it after it went off, as we already knew we were going to be spending a lot of time in an incipient stall condition, and could tell more from the changes in sound of the air going past us than some buzzer. But even in this environment, there are some instructors who just don't like doing stalls, so spend the minimum required amount of time teaching and practicing them.
If you are a pilot who learned in a Part 141 school, or in Part 61 but didn't spend a lot of time in deep stalls, one of the best investments you could make in yourself is to find an experienced instructor and ask to spend an hour doing "Falling Leaf" stalls, where you alternately keep the airplane in a deep stalled condition, and then recover while you really practice your rudder coordination. They're fun! You will loose your fear of stalls and develop skills/instincts that might save you in an situation like this pilot ended up in. You don't need a fancy aerobatic airplane, a Cessna 172 will work fine, but I prefer a 150 because it does not handle like a minivan.
Here's a good video on YouTubes to show what it would typically look and sound like during a lesson: https://www.youtube.com/watch?v=Ocv2YDLk5t0 Note that this is not an example of a perfectly textbook executed falling leaf, it's a student pilot performing them with varying degrees of competence (some good, some not.. keep them ailerons neutral!) and an proficient instructor allowing them to make some mistakes and experiment within the safe bounds of aircraft controlability. So a typical lesson with a good instructor.
This has been exacerbated over the years by the segregation of the pilot population into two separate groups, who often receive training that stresses different objectives.
Part 141 flight schools are the typical staring point for airline pilots. In these schools, even when flying little Pipers and Cessnas, stall avoidance is the primary method which is taught. Pilots are instructed to initiate a "stall recovery" at the "first indication of stall", which is taught to be stall warning horn indicator sound happening. The goal is to recover with no loss of altitude, and the technique is to add power to power out of the indicated stall immediately upon hearing the stall warning indicator, and use the elevator to keep the airplane at the same altitude. The problem is that the stall warning horn indicator typical starts sounding about 5 knots in advance of a fully developed stall when flying more or less straight and level. So these pilots never experience a fully developed stall, just an approach-to-stall, and often develop an extreme fear of entering an actual stall. This recovery technique also only works in an airliner in the case of an approach-to-stall or at most a very shallow stall. To recover an airliner from a fully developed stall, you must use the same techniques as you do in a Cessna 172, which is to drop the nose to lower the angle of attach and trade some altitude in for airspeed. This was vividly demonstrated by the five co-captains of Air France Flight 447, who tried to power their way out of a fully developed stall, that could have been easily recovered from by a typical student pilot using Cessna techniques.
I learned to fly in a Part 61 school, which typically are things like flying clubs and independent flight instructors teaching people who mostly fly for fun, or for light commercial use like charters, and will be mostly flying light propeller aircraft. In this environment, the aircraft have a much lower power to weight ratio, you cannot power your way out of even an approach-to-stall. Instead of stall avoidance, stall entry, recovery, and exit is taught. Instead of the goal being to minimizing altitude loss, maximizing aircraft control is taught. The goal is to prevent a poorly-handled stall from developing into a spin, which will usually result in a fatal accident like this one did. So if you learned in a Part 61 school, instead of starting recovery as soon as you heard the stall horn, you kept going until a full stall, and the expectation is that the student would say "STALL" when they identified that the airplane had entered a fully developed stall, based on changes in the handling characteristics and sudden drop in altitude. The student would then initiate a recovery by pushing the nose down to reduce the angle of attack, smoothly adding power and right rudder at the same time to add airspeed and counteract for yaw, and then recover from the resulting shallow dive with no more than 200' loss of altitude, but keeping the airplane under perfect directional control. So in part 61 schools, instead of recovering as soon as you heard the horn blip, you spent a lot of time with it going off in your ear. In fact my instructor used to pull the circuit breaker for it after it went off, as we already knew we were going to be spending a lot of time in an incipient stall condition, and could tell more from the changes in sound of the air going past us than some buzzer. But even in this environment, there are some instructors who just don't like doing stalls, so spend the minimum required amount of time teaching and practicing them.
If you are a pilot who learned in a Part 141 school, or in Part 61 but didn't spend a lot of time in deep stalls, one of the best investments you could make in yourself is to find an experienced instructor and ask to spend an hour doing "Falling Leaf" stalls, where you alternately keep the airplane in a deep stalled condition, and then recover while you really practice your rudder coordination. They're fun! You will loose your fear of stalls and develop skills/instincts that might save you in an situation like this pilot ended up in. You don't need a fancy aerobatic airplane, a Cessna 172 will work fine, but I prefer a 150 because it does not handle like a minivan.
Here's a good video on YouTubes to show what it would typically look and sound like during a lesson: https://www.youtube.com/watch?v=Ocv2YDLk5t0 Note that this is not an example of a perfectly textbook executed falling leaf, it's a student pilot performing them with varying degrees of competence (some good, some not.. keep them ailerons neutral!) and an proficient instructor allowing them to make some mistakes and experiment within the safe bounds of aircraft controlability. So a typical lesson with a good instructor.
> instead of recovering as soon as you heard the horn blip, you spent a lot of time with it going off in your ear. In fact my instructor used to pull the circuit breaker for it after it went off, as we already knew we were going to be spending a lot of time in an incipient stall condition, and could tell more from the changes in sound of the air going past us than some buzzer.
This is sort of the way I was taught. In primary training we'd always wind up doing a lot of minimum controllable airspeed work and then move on to power on stalls/departures and low power stalls/approaches. Recognition was pretty easy with the buffeting followed by the nose dropping. Coordination and control were the goals. Later on we'd also do accelerated stalls. I hated doing low speed work so my instructor made us do it every time even after I started doing them without him in the airplane.
This is sort of the way I was taught. In primary training we'd always wind up doing a lot of minimum controllable airspeed work and then move on to power on stalls/departures and low power stalls/approaches. Recognition was pretty easy with the buffeting followed by the nose dropping. Coordination and control were the goals. Later on we'd also do accelerated stalls. I hated doing low speed work so my instructor made us do it every time even after I started doing them without him in the airplane.
Here's another video of an instructor teaching a student falling leave stalls: https://www.youtube.com/watch?v=CpBX-B5mQ18
Not a pilot but I've dabbled a lot with flight simulators over the years. This is one of those things simulators struggle with. Even X-plane will just spin irrecoverably and crash when you try stuff like this.
Not a pilot but I've dabbled a lot with flight simulators over the years. This is one of those things simulators struggle with. Even X-plane will just spin irrecoverably and crash when you try stuff like this.
Yeah I got a PPL and there was no mention in my training of stuff like that which happened to this plane. That said I'm surprised it behaved like that - turning dramatically to one side on stalling. All planes I've flown, model aircraft that I've built and paper darts just lose lift when they stall rather than yawing to one side. It seems there was something off with the aerodynamics of that plane.
STOL kit and possibly trim setting causes tip stall rather than root.
Maybe the higher torque of the propeller?
I’ve got a few hundred hours in the usual pipers and light twin, but I’d say I never really learned about flying, and particularly “flying the wing” until I got into aerobatics and deliberately upsetting the aircraft. It’s priceless learning to go beyond the normal and being comfortable with it.
> Cessna aircraft have a hinge line on the upper surface. As a result, turning the aileron down causes a sharp angle on the upper surface. The air is unable to flow around such a sharp edge and stays attached. The result is a sudden right wing tip flow separation.
Should this say "The air is unable to flow around such a sharp edge and does not stay attached"?
Should this say "The air is unable to flow around such a sharp edge and does not stay attached"?
I also caught this seeming error. It stood out especially since the rest of the article is so well written. I don't know anything about flying so I thought it was perhaps a lay misunderstanding on my part.
I think it’s just a typo and the author meant to write “doesn’t stay attached.” In a stall the flow detaches: https://youtu.be/3Ahtc-uePY4?si=CPvBpZwx2YbPLFb3
I think it's just the "s" that got added: "the air is unable to [...] stay attached"
I love the thoroughness annd precision of aircraft accident investigations. Amazing watching these folks do their jobs.
Stalling with a wing drop at 15m, you will be hitting the ground or water before recovering, even with perfect technique.
It seems his takeoff technique was adequate for thousands of takeoffs until a gust hit at the wrong time and place and yanked the rug out from under him.
It seems his takeoff technique was adequate for thousands of takeoffs until a gust hit at the wrong time and place and yanked the rug out from under him.
> His opinion was that the Cessna 185 simply didn’t stall.
There's your problem. Don't opine on operating characteristics of a production aircraft. Read the handbook. This incident was caused by poor airmanship.
There's your problem. Don't opine on operating characteristics of a production aircraft. Read the handbook. This incident was caused by poor airmanship.
It seems like he was asked a question which compelled him to opine. You seem to be assuming that he went ‘out on a limb’ of his own accord, without any basis for that assumption.
No, I did not make that assumption.
His answer to the investigator's question should have been what the operating handbook says and not an opinion he held.
Even he was offering an opinion as addendum (that may have been edited out of context in reporting), it shouldn't be this one.
Even he was offering an opinion as addendum (that may have been edited out of context in reporting), it shouldn't be this one.
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It's normal for airplanes of the same model to fly differently: I fly a little fleet of six Citabrias, and their stall characteristics are radically different. You'd expect more uniformity from a modern aluminum airplane, but still: nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot.
The 40lbs of gas I burn flying for an hour decreases the stall speed by more than 1mph on those Citabrias I fly.
EDIT: I was mistaken, this isn't a requirement in Europe either.