After reviewing the published report on the NTSB web site, I believe they were attempting an engine out emergency landing as part of the Flight Review. Instructors should make sure that they are familiar with the aircraft they are giving instruction in. They also should never let a trainee get ahead of them. It is possible that the owner made a quick decision to change runways when he saw he didn't have enough altitude for the right downwind. Of course, it is also possible the instructor said "You're not going to make it that way, but you can from a close in left base". I remember a fatal at Montgomeryville, PA airport (long gone) the first year the BFR was required (1972?). A commercial pilot and instructor died in similar circumstances

I have something to say about hanging this flight isntructor out to dry. Part of our job is to train in real world conditions with real world scenarios. Often times you let a student take things to a point so that they learn more by doing, than by listening. I have not read the NTSB report, but I can say that given what I have heard, this instructor was doing his job. His student probably did get a little bit ahead of him. When things start going south in the airplane, we dont have a magic button to push to disengage the student flight controls, and it was quite possible that maybe, just maybe, the instructor on board tried to make things right, but was hampered by the pilot who was receiving the flight review. I am quite sickened by someone writing in about stupid flight instructors killing people. Anyone who cannot see that it is the flight instructors out there risking life and limb every day to ensure people are SAFE, cannot see the forest for the trees. Who ever wrote in with that comment needs to understand that insulting skilled instructors out there every day, doing their job, with skills way beyond his, is ignorant.

He should know better than to disrespect the very people who made him what he is today. The arrogance is sickening. We as instructors carry with us not only CFI, but PIC where ever we go. It is our job. How dare he insult our profession with such an ignorant opinion. I am not writing in about how we have to give flight reviews to people who have no business in aircraft!! I am not writing in, saying the title should be changed to stupid pilots, will kill CFIs. We work in harmony to achieve safety and this is just rediculous. I feel it is wrong to blame the person who sits in the right seat watching the pilot, instead of the real pilot in command.

Every time we step into an aircraft we wear that PIC hat, but we dont touch the flight controls until it is absolutely necessary, because that is our job! This accident took two lives, instead of blaming "stupid flight instructors" or "stupid pilots who need a flight review bi weekly" lets focus on how we can learn from this incident and stop it from happening again. Perhaps the pilot in this accident needed more than just a flight review, every 24 months, and perhaps the flight instructor on board should have applied power and told the pilot he failed instead of letting it go that far..Who killed who? Does it matter? Maybe pilots will realize that more training, more often, will keep them proficient. Maybe instructors will realize that everyone, no matter how confident and seemingly proficient, has the potential to put you in a situation that may be beyond your skill to recover from. We need to come together to fix the issue at hand, not split apart into camps with blame games! R. Hasiak Com. MEL/MES SEL/SES AIGI CFI/CFII

How about we go back to EVERYONE having to demonstrate spin entry and recovery. You don't soon forget the experience...

I train annually at APS in Scottsdale AZ and heartily recommend it for any pilot. There is not a spin I am concerned about in my Raven. They will taylor they're training to meet the needs of any airline pilot or GA pilot. Their customer service is outstanding and you will walk away with a great deal of confidence and knowledge. I think there would be many pilots alive today had they trained at APS.

One huge factor in this accident has not been addressed. It has nothing to do with basic aerodynamics, which are fun to argue about, but everything to do with the optical illusion when you are flying a pattern at 500 ft vs 1000 ft (approx). This illusion has been a factor in countless instrument circling approach accidents and is rarely identified as a factor. Here's the scoop. If you position yourself laterally out on downwind for what looks like a proper position to turn final, you will be about half the distance laterally from the runway as you are at 1000 ft with the same sight picture. These guys at their lower altitude probably thought they had plenty of room to make a turn toward the runway then roll out on final due to this illusion. If you don't believe this, fly a normal traffic pattern at 500 ft and use visual cues to turn final. You'll overshoot every time, or be surprised how close you came to overshooting. If you try this, use caution and be prepared to make a wide, overshooting go-around and don't try to "crank it around".

I hope Robert didn't take my comment as "hanging the instructor out to dry". I am also a CFI/CFII and am a former CSIP (Cirrus standardized instructor pilot). Unfortunately, when you get into any airplane as an instructor, you become the PIC who will be blamed for any accident/incident. By the way, the FAA will want to talk to you if you sign off a Flight Review and the pilot subsequently has an accident or incident. You also have to let the trainee make mistakes and see how they recover. The thin line is not to let them take you someplace where you can't recover. Familiarity with the airplane makes this much safer.

Daniel is right on. Every pilot should be encouraged to experience aerobatic flight. It teaches aircraft and personal limitations and a pilot with such a background will be a safer one.

Well, perhaps I am ignorant, in that I didn't take away any of these "political" implications from the video. As a low-time private pilot, I was simply impressed that the NTSB is now able to reconstruct an accident with on-board data recording similar to what has been the norm with airline black boxes for years. Especially when dealing with the ragged edge of the flight regime, for those that have never had spin or aerobatic training (like myself), a visualization like this is quite useful.

I am writing this a day after viewing the video, and purposely not going back to it. The two points that stick out in my mind are the following: Once truly committed to a course of action with no other alternatives, you really need to stick with it and make the best of it - fly as far into the crash as possible, as Bob Hoover says. In the case of practicing an engine out landing, the safety of the flight dictates that a go-around is still an option, and one that should have been implemented upon seeing the approach degrade so far. The second highlight was the apparent cross-controlled stall-to-spin. I'll open myself up to some criticism about learning good habits, but my compensation for a bit of "ground fear" is a few extra knots on base. As a renter who often flies different aircraft, I am simply not comfortable enough with any single plane to know exactly where the ragged edge is.

As a low-time pilot, I still put a lot of trust in the CFIs with whom I fly.

Demonstrating spin recovery as a part of flight training is very valuable,and perhaps that requirement should be re-instated, but not practical in a Cirrus, where spin recovery requires airframe-parachute deployment.

Two additional tidbits of information from the NTSB accident investigation may affect the interpretation of who was responsible for what during this flight. First, the instructor had no known experience with Cirrus aircraft. Hence, did the instructor have the knowledge and/or skill to recognize the situation and recover properly? Second, the approach was conducted with power at idle and flaps up, which the NTSB confirmed by matching recorded data with flight tests. That's an unusual configuration for landing a Cirrus as you transition from downwind-base-final. Hence, the observed low-altitude maneuvers were conducted in a configuration with higher stall speeds, which perhaps is another indication of lack of familiarity with Cirrus aircraft. This accident chain may include an early decision, the one by the instructor to conduct the flight review.

Thank you AVweb for this story. I have been a CFI for 36 years and I can tell you I learned a lot from the video, the podcast, and the above reader comments. I am involved in the FAA CFI workshop series and I will try and bring up this story to generate discussion among fellow CFIs. This is a quality presentation with valuable safety information for all pilots.

It's been a lot of years since I instructed (my CFII expired back in the mid-80s), but I can remember many times fighting with myself whether to take the controls or not--and having at least one very close call when my student would not relinquish the controls and had frozen--we were in a power-on spin in a 182 with back seat pax, which he had inadvertently entered during a departure stall demo. The only reason we are alive today is that I hit his wrists to get him to let go of the yoke, hard enough to bruise my left arm in 2 places. Clearly I had let things go too far in that case--but there had been enough altitude to recover.

Getting a panicked Cirrus pilot to let go of the side stick would be pretty difficult, I would think. Whether calmly saying "I have the controls" or screaming "Let me have the G D airplane!", the CFI might not have had any opportunity to take over--and an over-the-top stall/spin (i.e., a snap roll) can happen awfully fast.

It can be very hard to create real life scenarios without creating real life danger. I suppose if there is any lesson here for the rest of us, it is that being intimately familiar with the airplane is pretty important for any pilot, including CFIs giving biennials or any other check ride.

Cary

Not to lose what, to me, was one of the most striking elements of this story: it is absolutely amazing to me that data from a charred GA wreck, combined with thoughtful analysis of the data, can lead to such a precise, realistic recontruction of the events that one literally winces as the moment of impact approaches. This is not due to the theatrical display of trauma, but rather to the painstaking attention given to analysis the inexorable laws of flight, so brutally abused in this tragic case. Excellent job with this one, Paul.

Great discussion (thanks Paul) that by itself increases awareness and safety! I too am a CFI (and DPE) and have even had a student spin me on base (and still here) We now demo spins to all students in our school before practice area solo. AOA is a mystery until demonstrated, but no one can simulate the ground that close safely!

The data here is clear: 60 degrees bank and AOA at 17 degrees with only 223 ft agl is pretty far into an accident and any CFI would have been terminating this demonstration! The sudden yaw right would indicate a poorly initiated stall recovery; never released the stick pressure to break the stall, just tried to raise the wing. I also suspect power was added here and "energized" the rudder with the increased air flow (could they determine this from the recovered data?) I suspect this brought them over rapidly. That is the only way I have ever seen the over the top occur from this configuration in a non-aerobatic (rudder limited) plane. The Cirrus is more stable than most GA planes.

Too bad for both on board and Cirrus. I just completed CSIP training and have nothing but admiration for this amazing plane (pilot for 40 years, 10k dual given, 2200 spins)

Couldn't agree more with Daniel. Upset training, EMT, spin training, etc benefit pilots by allowing them to directly experience how excessive control inputs (or crossed inputs) might lead to unintended (and potentially deadly) consequences. While I am not sure that one or two days spin training will help one develop the habits to allow a successful recovery, learning the consequences of excessive control inputs is priceless.

The acro time I have in my Yak 55 has improved my skills in my Cirrus SR20 not because I might be able to recover from some type of spin/stall (which is irrelevant in the Cirrus anyway), rather it has given me a better idea of how easy it is to get into trouble and, hopefully, how to avoid it in the first place. To paraphrase Paul: no yanking and banking in the pattern.

Indeed, Paul deserves acknowledgment for this excellent presentation. However, please note that the NTSB investigation deserves credit for the 49-page analysis of the recorded flight data (with help from Avidyne), validation of flight parameters through flight tests (with help from Cirrus Aircraft), and video reconstruction of the simulated flight (included in the NTSB docket without credit, but using X-Plane likely by someone in the NTSB Vehicle Recorder Lab). So, the most dramatic element, the video, came from the accident investigators -- something very appreciated but unusual for a general aviation accident. The COPA community inspired by this NTSB work has begun to develop similar recreations of other accidents for their dramatic learning effects.

I also suspect power was added here and "energized" the rudder with the increased air flow (could they determine this from the recovered data?<<

Although the PFD retained data throughout, the MFD trace, where the power settings were stored, was too damaged to yield much beyond the initial power reduction.

Frankly, I am amazed they got anything out of it at all, given the damage.

If the left wing exceeded the stalling angle of attack, why didn't the plane roll off to the left?

Suppose the pilot actually was attempting to side slip leftward back to the runway during a simulated engine out; the wing's dihedral would put the left wing at a higher angle of attack, but the right wing would be lesser than in a coordinated turn. The left wing, although stalled, still produces enough lift to counter-balance the reduced lift on the right wing (also due to dihedral)--until the right wing 'lets go' too. Then the differential causes a rapid roll-off 'over the top'.

So, you see, it isn't the steep bank, but the slow slip that caused the accident.

If you want to line up with the runway instead of overshooting the centerline, steepen your bank. If you don't want to do a cross-control stall, keep the blasted ball centered. If you 'unload the wing' in a turn it'll have the same result as shallowing the bank--just the opposite effect that you're trying to achieve. If the steepness of the bank makes you uncomfortable--go around.

@Paul re MFD data: the lack of power data was by design rather than damage. The NTSB docket includes the aircraft performance study that confirms that both data streams from the Avidyne PFD and MFD were extracted. No mention is made of damage. By design, the PFD records flight attitude data more frequently than the MFD records general location and engine performance data. So, when electrical power is interrupted, as happens in a crash, up to the last minute of MFD data can be lost. Yes, it is amazing what the accident investigators can get from recorded data, and further remarkable the efforts their analaysis group go to validate and determine the flight characteristics that you present in your video story. Avidyne contributed to this effort by their Entegra avionics desgin, and new Cirrus aircraft contain a Recording Data Module with even more data streams. Our flying community has already learned a lot from these advances. Thanks for spreading the word.

" and thus a lower angle of attack is needed in the steady state glide."

Sorry, but this is not true. In a steady state glide, the angle of attack must still produce enough lift to EQUAL weight! It is that same angle of attack as in cruise flight because the weight is the same! If one accelerates down, THEN you get a lower angle of attack! What happens most often in this scenario is the pilot relaxes back pressure as they feel the G's increasing and the angle of attack does decrease, thus reducing the approach to stall. Then they realize they are going down too fast, either by the VSI or feel and pull back harder, force the nose around with top rudder, and violently snap over the top, thus increasing the value of the remaining Cirri!

David T,

As your observations are correct, they are WAY too aggressive for most pilots that low to the ground and have no place in training. If you don't want to feel compelled to "steepen the bank" as you turn final, then fly a better base. It is the set up for this base to final turn that matters. As a CSIP and multi thousand hour Gold Seal CFI, I can say that the instructor let it go too far! We ARE responsible for the actions or in-actions of whomever we instruct. Cary had the only likely exception mentioned above.

" and thus a lower angle of attack is needed in the steady state glide."

Sorry, but this is not true.<<

Actually, you are taking the statement out of context. In the example given, we are making a *comparison* between the steady state glide and the more highly loaded steep turn in which altitude is maintained with pitch/angle of attack to compensate for the lost vertical lift vector. It is *exactly* the comparison between straight and level at 1G and a 45-degree bank at 1.2G. During the transient, the latter requires more AOA than the former and you get that AOA with pitch. Higher load factors require more lift to maintain altitude; give up the altitude requirement and with it goes some of the need for lift, hence less AOA.

The statement in the video was this: "The wings weren't yet highly loaded because the airplane was descending slightly." This is correct. If the pilot had yanked into the bank and pulled sharp pitch at the same time to hold altitude, he would have had more loading than if he had let the pitch fall through. In reality, he pulled a little pitch and eventually leveled, but at that point, the load/AOA curves didn't come together.

Another way of looking at it rolling into a steep bank and pushing forward on the stick. It essentially makes the airplane weigh less, so less lift is needed.

I stand corrected. I missed that context. Thanks.

posted by Thomas Hill on December 24, 2009

"As your observations are correct, they are WAY too aggressive for most pilots that low to the ground and have no place in training."

What, exactly, has no place in training? Pylon racing? I agree. It comes down to the definition of "comfortable" doesn't it? I define it as being within one's limitations, not as being physically able to cope with the extreme attitude. Personally, 30° of bank is my pattern limit. I can make use of all kinds of other tricks that accomplish the same results without resorting to real steep banks. From your post, I believe you can too.

>I also suspect power was added here and "energized" the rudder with the increased air flow ... That is the only way I have ever seen the over the top occur from this configuration in a non-aerobatic (rudder limited) plane.<

Over-the-top is easy in a Cessna 120/140 (maybe 172 but can't really remember). I used to often do them for fun. All it took was hard top rudder at the entry to a turning stall.

>"and thus a lower angle of attack is needed in the steady state glide." Sorry, but this is not true.< >Actually, you are taking the statement out of context.<

I agree that you are correct in the context you meant, but when I read it I had the exact same reaction. I think your statement was worded such that it did seem to stand alone.

Steepening the bank in the pattern to avoid an overshoot, assuming that you follow the recommended 30° of bank advice, has no place in training. My comment was meant to acknowledge your apparent high skill level, just note that we can't go and teach that to students or any other skill level. Your 30° of bank limit is the standard and the absolute best way to fly the pattern. The one twist I teach is exactly 30° of bank in all turns in the pattern EXCEPT the base to final. There I teach no more than 30° of bank. I like the slightly earlier turn with planned and visualized roll onto final that this creates. If you want to learn the best stall control and feel, go fly gliders! Nothing better than thermalling to teach you feel, recognition, coordination, and instant recovery all at once.

I for one appreciate the reporting. The CFI is the PIC and needs to stay in control of the aircraft. Nevertheless I can imagine trying to wrestle away the controls from a freaked out student. It is an unfortunate accident. The purpose of reviewing and confronting these obvious CFI and student pilot shortcomings is to make sure it doesn't happen to us. Having said that, no one is perfect and it is never a good idea to be doing low speed high ban angle maneuvers so close to the ground. BTW remember the Cirrus that spun in back in NYC? I believe there was a CFI in that ship too.

"...Anyone who cannot see that it is the flight instructors out there risking life and limb every day to ensure people are SAFE, cannot see the forest for the trees..."

Well Robert, if you are out risking life and limb every day you are instructing, there is something wrong. An instructor has to know his OWN limitations (and the limitations of the aircraft he is flying) very well and make sure the person you are flying with never exceeds them. If you think you are "risking life and limb" every time you go out with a student, perhaps you should rethink your instructor ticket or your experience. In 8000 hours of dual given, I've only had to take the controls from one frozen pilot and it took the side of my hand against the adams apple to nake him let go. You gotta do what you gotta do.

It was also said that the instructor involved had no time in a Cirrus. That's a different airplane (I'm a CSIP) and NOBODY should instruct in an aircraft he is not thoroughly comfortable in and has been checked out in by a knowlegable and qualified instructor.

In addition, if you feel like you are risking life and limb every time you go our, you are probably unconsciously telegraphing that attitude to your students. We should be showing then the wonder and love of flying. Do some thinking.

Linda

"In addition, if you feel like you are risking life and limb every time you go our, you are probably unconsciously telegraphing that attitude to your students. We should be showing then the wonder and love of flying. Do some thinking."

Excellently stated!

I have been flying light aircraft and sailplanes for 47 years. The CFI that taught me to fly ferried bombers across the pond during WWII. The one thing she drilled into me was the feel for the airplane. We spent hours doing low level maneuvers and practicing sudden engine outs with the question "where are you going to land" always in my mind. You had to be able to set up the landing in seconds while keeping the airplane under control. This was in a Cessna 140. Today too many high achieving, financially well off people obtain their pilots licenses and then immediatly buy slick high performance airplanes with no true physical feeling for flight (seat of the pants feel and mental readyness). That is same reason the early V tail Bonanza became known as the "forked tail doctor killer" . When you start whipping and jerking an airplane around close to the ground you had better know how to maintain coordinated flight and have a feel for when the wings are approaching a stall. As someone once said "flying is not inherently dangerous but it is terribly unforgiving of mistakes"

The Cirrus stall-crash has resulted in related discussions about the relative safety of steep bank angles while descending. Paul says step bank angles can be made with relative impunity from stalls if descending. With due respect I join the dissenting side. Look at the picture on page 18 of the December issue of Aviation Safety. The glider pictured is in nearly a 60 degree banked turn (as measured with a plotter) while descending at 7 kts (700 fpm or nearly so). The g meter shows nearly 2 g's. The stall speed then must be "nearly" 1.4 Vs. The wing is certainly not unloaded. The picture is in an article by Tom Turner who also promotes the wing unloaded in a steady rate descent theory. Rather than being a shallow bank advocate I argue for proper speed control while maneuvering. If an inadvertent stall indication occurs at 1.4vs (for instance) simply releasing the back pressure and leveling the wings brings immediate recovery with little loss of altitude. Sad crash, great discussion.

I think something is missing from the comments. It's too easy to get wrapped up in the aerodynamics or what the flight instructor should have done. How about root cause analysis. David St. George touched on it but that's been it so far. What was the pilot trying to do when he increased the angle of attack and at the same time added rudder? Also as the airplane was snap rolling to the left why did the pilot not recognize the maneuver. To me, these are the pertinent questions, not what is the stall speed in a 54.72 degree bank. Uncoordinated flight is the issue, why was it being performed?

When I was taught to fly my CFI drilled in my head how wing loading and bank angle increase the stall speed. I was trained to tell myself to keep up the speed well above stall when maneuvering low to the ground as in a base to final turn. Over the years this has turned into wide base legs with shallower bank angles of higher speed when using steeper bank. I am sure this instructor knew this and would be surprised if it had not been covered in the training syllabus.

What about cockpit distraction? Isn't that the most likely scenario here? Perhaps there was an engine out training scenario, there are mistakes being made by the student with a cockpit discussion occurring during the maneuvers. I have learned distractions can be dangerous. This is worthy of discussion. I have experienced distraction in the form of "arguments" while receiving instrument currency check. This occurred during maneuvers with an instructor and I felt I was behind the airplane (even though VFR). Not good.

>>What was the pilot trying to do when he increased the angle of attack and at the same time added rudder?<<

From what we can tell, he didn't increase the angle of attack. He failed to decrease it ahead of applying rudder. (We think.)

>>Also as the airplane was snap rolling to the left why did the pilot not recognize the maneuver. To me, these are the pertinent questions, not what is the stall speed in a 54.72 degree bank.<<

That's the entire point of this exercise, to pass along enough aerodynamic knowledge and seat-of-the-pants common sense to understand what will kill you before it does.

There is little question the lack of supervision led to the situation. I was curious why the NTSB thought the roll to the right was a result of pilot action. In a coordinated turning stall, the a/c should always roll "over the top"!

>>Paul says step bank angles can be made with relative impunity from stalls if descending. With due respect I join the dissenting side.<<

Try this thought experiment: Ever done an overhead approach? Let's do one. 45-degree turns throughout. Enter the upwind at 110 knots, reduce the power, let the nose fall through and roll into your descending banked turn. What's the load factor doing? Angle of attack is not increasing and is probably decreasing a little during the transient. It will increase some if you slow down.

Now try the same exercise, reduce the power, roll into the bank, but hold the pitch and don't let the nose fall through. What's the load factor doing? What's the angle of attack doing? Remember, an unloaded wing below the stall angle of attack cannot stall.

And by the way, "unloaded" doesn't mean zero load, it means less load. So you have to parse the unloaded wing concept with a certain amount of common sense. You're not going to do 60 degrees banks on an overhead. I can make a wing stall at 45 degrees and 1.2G. But to get there,I have to exceed the stall AOA, which I can only do with pitch in this scenario. If I don't apply sufficient pitch, I won't stall.

You use "proper speed control" as the argument because that's what you've been taught, as have we all. In reality, airspeed is merely a surrogate for AOA because we have nothing else to work with.If we had AOA indicators and had been taught AOA, we might not have the problem.

"In a coordinated turning stall, the a/c should always roll "over the top"!"

Jim, no, in a coordinated stall, the airplane will have very little roll! If the ball is centered, the airplane doesn't know or care which way is up. Many have slightly more dihedral on the left wing to compensate for all the left turn tendencies, and so it MAY stall slightly earlier, but otherwise it should have little roll at all. If you stall and the airplane reverses bank over the top, you were not coordinated OR p-factor got a little payback on you. Very few airplanes have enough power to snap you over like this, though. Again, all this assumes coordinated and in a stall and a bank the ball ain't always being truthful, either, so coordinated can be more difficult if you aren't fully versed in feeling with the butt cheeks!

In addition, if you feel like you are risking life and limb every time you go our, you are probably unconsciously telegraphing that attitude to your students. We should be showing then the wonder and love of flying. Do some thinking.

woa woa woa hunny slow your roll...you dont know anything about me darlin, nor how I instruct. I would appreciate it if you would keep that in mind before lecturing me. I have a long and distinguished list of happy students who never ever got any impression of that. As far as 8 gagillion hours of dual given with one frozen student is quite admirable. But the reality linda is everytime you go up there, you are in danger! Anything can happen, and many people might be able to overpower you. 8000 hours dual given simply doesnt mean you can know whats going on based on a statement I made..PERIOD. Happy holidays all!

I would like to remind everyone that the NTSB reports are filled with plenty of high time instructors, with many hours in make and model. Simply stating that one instructor didnt pay 3 grand to go to minnesota for a day..rendered him ineffective as an instructor is a stretch. He passed the same checkride we all did, from the same FAA. It has wings, it flies conventionally, and there are plenty of safe low time cirrus pilots to prove that time in type is not the almighty factor of safety we claim it to be. I beleive COPA just came out with a study showing that low time pilots in cirri are safer than those with many more hours in type. I guess some people have a vivid imagination, but I didnt mean to suggest that I or any of my fellow instructors have an ATTITUDE of student pilots are out there trying to kill us, as I read back I still dont read that out of what I said...but everyone has their own opinions. Linda im sure your a great instructor, I dont know you, and I would never suggest you are anything but a great instructor, especially in a public forum when I dont even know you, I ask the same courtesty of you. Merry Xmas all!

This dialog goes to the heart of aviation safety; 67% of accidents happen during maneuvering flight where we spend only 5% of our time flying! By way of moderating, it appears we all agree these guys were in serious trouble but "How and Why?" would be the operative question. I think to improve our "safety culture" we should all impose an objective personal limit based on safety, experience and learning outcome; maybe 45 degrees bank and/or >500agl for instructional emergency scenarios while in the pattern? Below that an absolute agreed "knock it off," go-around and recover. If minimums are stated clearly before instruction both parties will have a predetermined response (the key to safety in aviation; "pre-think"). Any "yank and bank" below 1000 should be yellow alert and and below 500 agl at >30 degrees bank is recovery time (gravity works)! During instruction we do have to take a client beyond their "comfort zone" to build confidence and increase skills but a comfortable safely margin must be maintained.

This podcast by Paul B. with John King and Rich Stowell was very good; http://www.avweb.com/podcast/files/2009-12-21_AvSafety_StallsAndSpins.mp3

Here also is an article on slip/skid and turning stalls: http://faaflighttest.us/Cross-Controlled.pdf Enjoy the holidays!

Robert, I was reacting to your comment, not you.

Oh, and I do not answer to "hunny" or "darlin" -- my name is Linda, or as Toledo approach once told a condscending airline pilot, "That will be Captain to you, sir."

Was it the instructor's fault - yes, but I understand how it could have happened. I once had a nervous student try to fly me into a 100ft tower that was located on base to final. He froze on the controls and I had to scream at him to get him to let go. The situation really freaked me out, and I had to spend a few hours discussing it with one of the "old hands" at the airport. He told me that the fire extinguisher was for more than fighting fires, and that the student would forgive me for the bump in the head if I saved us from an accident. Thankfully I never had to use this tactic. As for the spin training - I always require private pilots to be able to demonstrate spin entry and recovery - I remember my first one and am thankful my CFI tactfully introduced me to spins prior to my first solo. Besides, spins are fun once you understand them!

posted by Paul Bertorelli on December 24, 2009

"Try this thought experiment: Ever done an overhead approach? Let's do one. 45-degree turns throughout. Enter the upwind at 110 knots, reduce the power, let the nose fall through and roll into your descending banked turn. What's the load factor doing? Angle of attack is not increasing and is probably decreasing a little during the transient. It will increase some if you slow down."

Reducing the prop blast over the horizontal tail surface would cause a lower AoA. In your thought experiment, the load factor will increase even if the elevator is not pulled back, but the degree will be offset by the effect of the power reduction. When the plane stabilizes the load factor will be higher than before. The reason is gravity no longer prevents curved flight (as a result of the cruise AoA setting) and curved flight comes with a price tag called load factor.

The point is: Pilots must use AoA to turn sharper. Releasing back pressure widens the turn. The good news is, for every airspeed, there exists a maximum bank angle that affords plenty of stall protection. If pilots always stay below that bank angle the wing can't stall. For starters, I'd recommend 1.3 Vs + 10 kias (for the configuration) as a minimum speed when turning and 30° as a maximum bank until lined up on final. Then reduce to the appropriate wings-level approach speed.

That's my advice this Christmas day--and a merry one to all!

Dave T.

>>Reducing the prop blast over the horizontal tail surface would cause a lower AoA.<<

Good point. Actually, I believe the loss of and therefore change in the thrust vector is the larger factor here. I don't have the formula to prove that. Can't find in ANA. Kershner may have it. If you have the right formula, maybe we can see for sure.

Point is, load factor *does not* increase appreciably in this scenario and that is why it's perfectly plausible to make the 45-degree descending spiral in an overhead. It is essentially a spiral dive.

In your experiment does the thrust vector change in a glider too?

DT

In your experiment does the thrust vector change in a glider too? <<

Only when you pull the tow rope release.

Thomas, When an aircraft is circling in coordinated flight the inside wing is always traveling slower than the outside wing. This is because the circle it travels in is shorter than the outside wing thus the lower velocity of the air flowing over it. Because of this lower velocity it generates less lift which leads the pilot to apply top aileron to counteract the overbanking tendency, further pushing that wing into a stall. This is not as pronounced in powered aircraft due to their shorter wings. In sailplanes with 15 to 25 meter wings it is very pronounced. When centering a small weak thermal you are forced to fly right on the edge of a stall in a bank that can exceed 45 or more degrees. It is common in sailplanes to carry a little top aileron and maybe a small amount of top rudder under these conditions. Not very efficient but sometimes it is the only way to stay in a small thermal and climb. When flying in tight conditions like this you are "spring loaded" to push the stick to break a down wing stall followed by a momentary roll toward wings level, acceleration and then a roll bsck into the thermal. If a stall goes uncorrected the plane will go over the top and enter an inverted spin. Through a little momentary inattention I let it happened to me in a small turbulent thermal while flying an ASW20 with full ballast tanks . You can beleive I never let it happen again!

Gary, I also had experiences while "cored" in very strong lift of actually being fully stalled in an old 2-22, buffeting and bucking but still climbing, LOL. Thomas Hill further back in the thread does not agree on the "over the top". After 45 years and 15K+, I can tell you that a lot of a/c have rolled over the top if the stall recovery is not prompt and correct. Power on/off, left or right, we are used to recovering "on top" wings level. But hold the back pressure and watch it roll! Merry Christmas

Gary, by over the top I meant a situation like happened to this Cirrus where the down wing rolled completely out and over the other side, not the situation of which you speak where the craft steepens the bank into the turn. This pilot seemed to be using top rudder which cause the un-coordination and spin. I've never had a glider come out of the bank and over the top, but only drop the down wing further as the stall aggravates. I'm sure it would if grossly un-coordinated. You've had one roll out and over?

Jim, no I completely understand that an aircraft will come out over the top, just not if well coordinated. Snap rolls are fun in the right airplane, just not in a Cirrus at 250 AGL. I've had a student do it to me, but I was ready and caught it just as it snapped. In a 152 as I recall. Made him a believer, I tell ya! And I've done plenty on purpose at altitude in a wonderful RV-4! What a fun airplane!

Now David and Paul, where does the thrust vector come from in a glider after rope release? Every glider I have flown has thrust. It must! Comes from pointin' that lift vector where you wanna go! Ya still gotta have all four forces.

Tom says, I paraphrase, a glider has thrust created by lift acting as thrust in the "4 forces". That's a common thought but it can't be. However there is a component of weight along the glider's flight path which makes in go. Weight is a prime force toward the center of the earth and will have a component along the flight path because the glider at constant airspeed (not trading speed for height)is always descending (with relation to the air mass it is in even though the air may be rising more than the glider is sinking). Lift as we diagram it perpendicular to the flight path is itself a component of the total aerodymanic force created by the glider. That aerodynamic force is always slanted rearward with relation to the flight path and cannot have a forward component along the flight path. The glider has only two prime forces, the weight and the aerodynamic force. We commonly break the aerodynamic force into lift( perpendicular to the flight path)and drag (rearward along the flight path)which are components. In that sense we can say "3 forces". We can't with any logic say "4 forces' for a glider.

A stall in a slipping turn will go "over the top". A stall in a skidding turn will go toward the low wing.

Jaime, we can agree to disagree. I call it thrust, most call it lift in the forward direction. Weight, by definition, always points down, but lift is perpendicular to the flight path. As you said, that path is always down even though it may be climbing. So the only thing that can cause forward motion is indeed lift pointed in that direction. I can take that lift vector and point it anywhere I want. Look at it this way, if you put the nose straight down, the flight path will be in the direction above the wings. Three forces, ok, I concede that, but lift takes the place of thrust as well as adds to drag. We just look at total drag and point it aft.

Thomas, Yes we disagree and I wouldn't normally respond to beat a dead horse but I'm snowed in so will try once more. There are two real forces. The total sum aerodynamic force is slanted back in relation to the flight path. That force or any part of it cannot "pull" the glider forward. Weight is the other force. It is slanted forward (slightly) from the flight path. Part of it can "pull" the glider forward. We are impolitely off topic (Cirrus crash) so I now promise to drop it.

posted by Thomas Hill on December 25, 2009

"Now David and Paul, where does the thrust vector come from in a glider after rope release? Every glider I have flown has thrust."

Speaking for myself, it comes from below. If you want more of it, point the nose down. For less, raise it up. Raising the nose would be akin to a reduction in power setting, wouldn't it? So I'm mystified by Paul's contention that the angle of attack would decrease on account of a change in the thrust vector (a reduction) of a powered airplane.

My interest in this discussion is confined to discouraging the notion that by steepening the bank while releasing back pressure a pilot can some how achieve the impossible and actually have his cake and eat it too! It would be like driving with the brakes on. If that isn't what Paul is suggesting, then I apologize for missing his point. If one wants to tighten up a turn, one must increase the angle of attack without exceeding the stall angle. It's as simple as that.

Dave T.

There is no "thrust" in a glider, just gravity. If you maintain 1 G gliding it reacts aerodynamically like any other plane flying level. The square root of the total G load is the multiplier of the unaccelerated stall speed. 60 degree bank (level) = 2 Gs; 41.4% increase in "stall speed." If you reduce pitch as you increase bank so as to maintain 1 G glide (overhead) there is no increase in AOA and no increase in stall speed (bank all you want but the ground will intervene eventually) These guys were low and the ground was the problem, they pulled up and accelerated the stall with bank...the question in my mind is the eventual roll right that caused the loss of control. A skidded turn (bottom rudder) will tuck under and spin. A slipping turn in most GA aircraft (rudder toward the high wing) is quite stable since roll and yaw are in opposition. Power is very important; any sudden application of power will immediately snap most planes "over the top" since the wind from the prop over the tail gives the rudder sudden and surprising effectiveness (I demonstrate this in flight to pilots at least once a week) I think this might have been the cause of this accident. Unfortunately these people proved once again that power alone cannot recover a stall (but certainly can make it worse).

My comment on the tow rope was tongue in cheek, but it is nonetheless accurate. The forces on a glider are the same as on an airplane except in full glide, thrust is gravity. Been a while since I've chopped the tow and I can't remember if the nose falls through as it does in a power airplane when the power is reduced.

In any case, the glider example explained by David St. George applies directly to the Cirrus scenario. When it's in lift and gaining altitude, a glider is actually descending in a rising column of air--it is in a spiral dive. It can be made to stall if the pilot tightens the turn rate/radius enough through a combination of pitch and bank.

But as noted, at incipient stall, what does the pilot do first? Most likely immediately relax the pitch and/or roll out bank at the same time. Relaxing the pitch changes the lift vector and it also reduces AOA, both of which increase the descent rate and decrease the turn rate while increasing the radius.

David, I have never tried this in a G-meter equipped airplane, but can you roll into the steep bank, say up to 45 degrees and relax the pitch such as to show 1G throughout? I would expect to see a minor transient.

Well, THIS David says you can, for a while, keep whatever 'g' force you wish, whether 1g, 0g or, say, 1.3g. As long as it's less than than the 1.4g established by Mother Nature for a 45° bank, your airspeed will build. When speed ceases to increase, the load factor will be 1.4g and the turn will be less tight than before. My logic is that during the transition to a wider radius, the radius was increasing smoothly, so there's no benefit beyond stall avoidance for relaxing the back pressure in the first place if what you really want to do is tighten your turn. I'm not entirely sure you mean to say that, but I've heard other pilots say they can tighten the turn as long as they remember to "unload the wing". For those who may be in attendance here who think that--I wish to challenge their premise.

DAve Tuuri

A steepening bank at 1 G is exactly the "death spiral" scenario that often kills an inattentive/inexperienced instrument pilot; you never "feel" it because it is all 1 G (feels normal). This Cirrus pilot was adding back pressure (resultant AOA) thereby loading the wings accelerating the stall. He definitely should have released this pressure first while rolling to level and simultaneously adding power to arrest the descent. Recovery at that altitude would have required a definite "knock it off" and very positive and correct control input to recover.

Aerodynamics is always a compromise; David Tuuri is absolutely right. If you bank steeper and lower the nose (to prevent a stall) this does NOT accomplish a more rapid turn (no free lunch). The turn radius increases and the turn rate decreases with additional speed (and you meet the ground sooner). This also is why the "impossible turn" is such a widely debated enigma: it's a total compromise of applied forces to achieve the optimum turn rate without increasing descent. If you fly SLOWER at a steep bank (just above stall) your rate of turn will be GREATER (not intuitive). Since increase in stall speed is logarithmic not linear 45 degrees is a good limit which will always work at your approach speed (1.3 X VSo (what we recommend in gliders)

Avweb please stop sending me comments on this thread. I have unchecked the box two or three times. What else need I do?

Hi, Jaime — the next time you get a comments e-mail, look near the bottom of the message body. There should be a link at the bottom of each notification e-mail that says "Unsubscribe from Further Notices on This Topic" — or something to that effect (I don't have one in front of me at the moment). If you click on that link, you should stop getting the notifications.

Scott Simmons webmaster

We can argue aerodynamics all day long, the simple fact is the Cirrus line of aircraft are at best poor faxcimiles of an airplane and the pilots that learn in them are not much better, the factory program strips pilots of any ability they may have to truly feel an airplane and replaces good stick and rudder skills with a terribly flawed aircraft management system that uses the CAPS as a crutch for the shortcomings of the aircraft and the pilots that operate them.

@John Wesley: Wow! Tell us how you really feel!

Fortunately, I enjoy the companionship of over 4000 owners and 7000 pilots who feel differently and who have flown almost 3.5 million hours. By the way, the fatal accident rate in a Cirrus has dropped to about 1.54 fatal accidents per 100,000 hours. So, for such a flawed, poor facsimile of an airplane flown by pilots with crutches, it has fewer fatal accidents than the average single-engine piston aircraft. What's up with that, eh?

>>it has fewer fatal accidents than the average single-engine piston aircraft. What's up with that, eh?<<

Possibly faulty data is what's up with that. Recently, I've gotten a couple of e-mails questioning the claimed accident rate for Cirrus aircraft from two owners who have done their own research. We're once again scouring the available data to see whose claims are correct. I'm open minded but skeptical.

My own research reveals that on a per accident basis and accidents per registration basis, a larger percentage of Cirrus accidents are fatal compared to other types--far higher than Diamond, for instance.

That said, I think the Cirrus airplanes are terrific and a huge boon to the industry. While I don't believe they have inherent safety flaws, I'm not inclined to get my pants snagged on boosterism about the accident rate.

Everyone has an opinion, mine just doesnt buy into the hype, the Diamond is a better airplane for the money and Diamond does not support a traing program that literally tells a pilot to not fly the airplane, instead to let the A/P do everything and for the pilot to only monitor the boxes. All the time with his head down not observing anything outside. Every Cirrus pilot that I have flown with, even when flying something else, never looks outside the airplane. Granted Cirrus has made tremendous technological gains that are of a huge benefit to the industry as a whole, but at what cost to the skill and quality level of the pilots. Does anybody but me have a problem with an airplane with a boost pump that does not have the capcity to run the engine should the engine driven pump fail?????

Ouch! Insulted twice in one post, Paul!

"Boosterism" -- for responding with facts to John's opinion-laced diatribe. Indeed.  

"Faulty data" -- for presenting facts published in Cirrus Pilot magazine & on the web for anyone to review, rebut or reconsider their own flying.

As for the data -- where are there comparable statistics for hours flown by type? Cirrus Aircraft logs hours from warranty claims and SB compliance cards. 4,300 aircraft produced that fly a lot.

Then take the Nall report, back out fatal accidents in twins and jets, back out those hours flown from FAA GA survey, and compute #fatals in single-engine piston per hours flown. Last time I did this, rate was 1.86.  

As for Diamond comparison, no argument from me. That fleet has few fatals. Also has a large portion of training planes and hours, with small portion of cross-country travellers.

As for other comparisons, no question that there are way too many in Cirrus. But uninformed opinions like John's do little to change things. Fortunately, COPA members have a much lower fatal accident rate than non-member Cirrus pilots.

I have to take exception to your comment about my uninformed opinion, I have been instructing since 1968, maybe I dont read all of the Nall reports, or spend my time with operations like COPA, but I have flown thousands of hours with students of all kinds in many differant makes and models aircraft, 104 of them at last count. I have taken notice of a very serious trend, one that is fostered in a large part by the advent of the Cirrus and Cirrus type aircraft and the new tech equipment that goes with them. Pilots no longer look ouside, their stick and rudder skills are abysmal at best and they cannot navigate from one end of the airport to the other without a functioning GPS. I would much rather train a student in a Diamond or a 172 or even a Cherokee 140, I would much rather go XC in a 206 or a Bonanza or a Meyers 200 or a DA40, I also much prefer a training program that teaches a pilot to think through and work out problems instead of reaching for the CAPS. The Cirrus is a good XC airplane for the businessman pilot who flies a lot of hours, but it is not a fun airplane for the weekend or occasional Pilot and that is my opinion from the experiances that I have had with the airplane. I have to wonder, if the pilots involved in the original post here, had better stick and rudder skills, maybe the outcome would have been differant.

Sorry, no intent to be insulting. Just questioning claims I see go by me all the time.

My last sweep of fatals, which unearthed the accident upon which this blog is based, revealed that 46 percent of all Cirrus accidents are fatal. That's the highest percentage of any types we have reviewed. (For like years and periods, the number for the 182 is 34 percent, it's 33 percent for Mooneys and the same for Diamonds, which have too few fatals to make much of.

I therefore am skeptical of the Cirrus rate claim because the only source of it is the manufacturer, since it generates the hours on which the claim is based. Even if if the hours are correct and the rate is low, the high fatal percentage suggests lower odds of survival.

When I refer to boosterism, I'm talking about the manufacturer.

@John re taking exception: Noted. 

Please go back to your first post and re-read your statements of fact, as well as your sweeping generalizations, the ones based on your limited exposure and strongly expressed opinions. 

Opinions welcome. Reasoned arguments welcome  Hyperbolic arguments cast an unflattering light on you. 

Appreciate your stated experience and opinions. 

I simply note that approaching a thousand Cirrus pilots have undergone the weekend Cirrus Pilot Proficiency Program, where our flight instructors will refuse to sign-off on the recurrent flight syllabus if a pilot demonstrates what you claim every Cirrus pilot does. Has happened. But rarely. And most of those instructors have more than a 1,000 hours dual given in Cirrus type aircraft. They expect and demand high standards.   

For the sake of all Cirrus pilots, like the one in this fatal accident, I pray that each of them flies with an instructor that offers a greater level of awareness and professionalism.  Pilot-related causes account for over 90% of Cirrus fatal accidents.  And most of those pilots have lots of flight experience.   

That's why Paul's work is so important.     

@John re "I have to wonder, if the pilots involved in the original post here, had better stick and rudder skills, maybe the outcome would have been differant."

No wondering. Yes  I believe it would 

But more important to me is the skill of aeronautical decision-making. Chose your instructor wisely. Recognize what you don't know. Maintain awareness of your situation. Understand the @John re "I have to wonder, if the pilots involved in the original post here, had better stick and rudder skills, maybe the outcome would have been differant."

No wondering. Yes  I believe it would 

But more important to me is the skill of aeronautical decision-making. Chose your instructor wisely. Recognize what you don't know. Maintain awareness of your situation. Understand the edges of your flying envelope of safety. Act to mitigate risks. 

Recall the adage: a superior pilot uses his superior judgment to avoid having to exercise his superior skill. 

I don't think it's just Cirri pilots who get hung up on the doodads inside the airplane. Even way back when, in ancient times when I was instructing, putting a newbie in a superbly equipped (for the time) airplane was a guarantee that he/she would look at the dials rather than through the windows. Put that same newbie into a glass cockpit airplane today, and the same thing happens today. The cure way back when was to put a towel over the panel, and I suppose the same thing could be used now--but turning the dial down and blacking out the screens would work as well.

The first steps in learning to fly any airplane have to be to learn to fly the airplane--not the doodads. Whether today's relatively low time instructors are failing in that arena, I'm not prepared to say. But for certain, if a pilot or instructor cannot really fly the airplane, i.e., lacks good stick & rudder skills, none of the doodads will help him/her do it in a tight situation which really requires stick & rudder skills and not doodad monitoring skills.

Perhaps what my first instructor told me some 38 years ago was absolutely right, when I asked about the more advanced avionics than our 150s had: "First you have to learn to fly the airplane. We'll worry about all that other stuff later."

Cary

Speaking of Cirri -- and other digital display cockpits -- it seems if all the do-dads give the pilots a false sense of confidence. With all this technology how can anything go wrong....go wrong....go wr...

Now, I must admit that this observation is anecdotal and I don't know of any studies that may prove this, but I am not the only instructor who has noted this.

The Cirrus is a fine airplane, and the referenced accident would probably have happened no matter the mnake and model being flown.

Loved Cary's towel analogy, we did that for pre solo AND for Commercial maneuver training. That was before we started spending $800 so we couldn't hear the airframe and engine talk to us, LOL.