Testing the Impossible Turn

[dmccormack]

That's the airspeed recommended by Prof. Rogers. For a pilot who plans on using his method, I can see how Ron's recommendation to have CFI on board when trying it for the first time would make sense.

One can, of course, use a higher airspeed, at the price of losing more altitude than Rogers predicts.

Right -- see my earlier post -- the total altitude loss + turning radius difference between 45 MPH and 60 mph is negligible.

 

[Palmpilot]

Right -- see my earlier post -- the total altitude loss + turning radius difference between 45 MPH and 60 mph is negligible.

An 11% or so increase in altitude loss could make the difference between reaching a safe landing or not, but if you still see that as negligible, what is the point of incurring a greater chance of losing control of the airplane for no reduction in altitude loss?

 

[dmccormack]

An 11% or so increase in altitude loss could make the difference between reaching a safe landing or not, but if you still see that as neglibible, what is the point of incurring a greater chance of losing control of the airplane for no reduction in altitude loss?

I can tell you this -- few pilots I've flown with so far (perhaps one or maybe the other) will default to a "just above stall" 60 degree bank turn in the engine out on takeoff situation.

The more likley result in this situation is the more natural human clutch action, more likely a pull back will occur to "hurry the airplane around" -- and perhaps a cross-control when the bank gets "too steep" without enough rudder...

This is a classic case where theory doesn't account for reality -- gusts, panic, the rest.

In my airplane, 1g stall speed with me and full fuel is about 38 MPH.

I'm comfortable power on, level 60 degree turns at 60. Of course the g load is increased because I'm level.

Power off, maintaining 60 mph takes quite a bit of nose down during the 60 degree turn. It's a bit disorienting and when you finish the 180, takes a moment to figure out where you are.

At 50 mph in a descending 60 degree bank the airplane feels mushy (no stall indicator except aerodynanmic sensations).

But the altitude loss is about the same -- ~300 feet.

 

[PittsDriver]

A Pitts pilot that regularly performs "arcing" finals would have no problem. A Cessna pilot that always performed "stable" approaches?

I come over the fence at 95 mph and roll on at about 80 mph. A Cessna pilot is going to have a lot more time to think and maneuver than I am but they're ability to use that advantage will depend on if they've ever developed some skill. I practice a simulated engine out landing to an exact spot almost every time I fly - which I suspect many pilots don't do nearly often enough.

 

[Palmpilot]

I can tell you this -- few pilots I've flown with so far (perhaps one or maybe the other) will default to a "just above stall" 60 degree bank turn in the engine out on takeoff situation.

The more likley result in this situation is the more natural human clutch action, more likely a pull back will occur to "hurry the airplane around" -- and perhaps a cross-control when the bank gets "too steep" without enough rudder...

This is a classic case where theory doesn't account for reality -- gusts, panic, the rest.

It sounds like we agree that a 60 degree bank creates a risk of loss of control.

In my airplane, 1g stall speed with me and full fuel is about 38 MPH.

I'm comfortable power on, level 60 degree turns at 60. Of course the g load is increased because I'm level.

Power off, maintaining 60 mph takes quite a bit of nose down during the 60 degree turn. It's a bit disorienting and when you finish the 180, takes a moment to figure out where you are.

At 50 mph in a descending 60 degree bank the airplane feels mushy (no stall indicator except aerodynanmic sensations).

But the altitude loss is about the same -- ~300 feet.

So if a 60 degree bank does not reduce the altitude loss, would you agree that it increases the risk without providing a benefit?

 

[dmccormack]

So if a 60 degree bank does not reduce the altitude loss, would you agree that it increases the risk without providing a benefit?

I'm not sure what the question is.

I think at 60 MPH with a 60 degree bank, I turn quickly, lose about 300 feet, and get truned back towards the airport without being on the edge of stall.

At 50 (still 10 MPH above 1g stall speed), the airplane feels a but mushy and control isn't as assured (a gust could be Very bad).

 

[PittsDriver]

It sounds like we agree that a 60 degree bank creates a risk of loss of control.

Why in the world would anyone agree to such a thing? Just because the stall speed is higher in a 60 degree bank than a 45 or 30 why does that equate to higher risk? Is it because it is believed that stalls are somehow more sinister at high bank angles? In turns generally?

I would agree that the risk is higher for anything you're not skilled at that you might be trying for the first time in an emergency but that's a different point than saying 60 degree banks are inherently more risky.

 

[Capt. Geoffrey Thorpe]

Just because the stall speed is higher in a 60 degree bank than a 45 or 30

It is?

I would agree that the risk is higher for anything you're not skilled at that you might be trying for the first time in an emergency but that's a different point than saying 60 degree banks are inherently more risky.

That I'll agree with.

 

[gismo]

It is?

It is if you're in a coordinated turn and aren't changing your vertical velocity, oherwise all bets are off.

 

[PittsDriver]

It is?

I obviously meant with the increased G load which you'll want in this turn.

 

[dmccormack]

I obviously meant with the increased G load which you'll want in this turn.

Well...

You're in a power off descending turn.

Helps reduce the load significantly.

 

[ebetancourt]

It's amazing, I regularly do "coordinated" 90 - 110 degree bank turns without stalling or losing control. My Citabria must read a different aerodynamics book. :smile:

 

[mantakos]

You're in a power off descending turn.

Helps reduce the load significantly.

I think that's a bit of a myth. If you're in a constant-rate descent, then your wing is necessarily generating all the lift needed to haul the plane around in an arc, and all the lift needed to carry the plane's weight. You may get a tiny bit of boost from a vertical component of drag, but it's not significant.
-harry

 

[gismo]

Well...

You're in a power off descending turn.

Helps reduce the load significantly.

Descending in a turn doesn't decrease the load at all. Slipping does, and accelerating towards the ground will (but not for long).

 

[gismo]

You may get a tiny bit of boost from a vertical component of drag...

Not if the turn is coordinated.

 

[brcase]

Descending in a turn doesn't decrease the load at all. Slipping does, and accelerating towards the ground will (but not for long).

Serious question, What indicated bank angle does it take to equal a 2g turn when the nose is 30 degrees down? How about 60 degree down?

You say What? So think about this scenerio. My glider has speed limiting flaps meaning it can go into a vertical dive without exceeding Vne. So if my nose is 90 degrees down,What is a 60 degree bank angle(obviously it is only 1g)? How about 80 degrees down or 70 degrees down? Then how many G's am a pulling once stablized?

Some one better than me at the geometry might be able figure this out.

I suspect but can't yet prove that this might explain why you don't normally pull as many G's in a descending turn.

Brian

 

[mantakos]

Not if the turn is coordinated.

What does coordinated have to do with it? If you're traveling vertically through the air, then you're generating drag in the vertical direction. This is an academic point, though, as the effect is not significant enough to impact load factor.
-harry

 

[mantakos]

... My glider has speed limiting flaps meaning it can go into a vertical dive without exceeding Vne. So if my nose is 90 degrees down...

Then you've figured out a way to make that vertical component of drag significant, as it becomes enough to support the entire weight of your plane/glider as you reach terminal velocity.

In typical flight, though, our downward velocity isn't enough to generate enough vertical drag to support any significant portion of the weight of the plane.
-harry

 

[Palmpilot]

I'm not sure what the question is.

Sorry, when you wrote "the total altitude loss + turning radius difference between 45 MPH and 60 mph is negligible," I misread it as "the total altitude loss + turning radius difference between 45 degrees and 60 degrees is negligible." My mistake - no wonder my questions weren't making sense to you!

I think at 60 MPH with a 60 degree bank, I turn quickly, lose about 300 feet, and get truned back towards the airport without being on the edge of stall.

Have you tried it at 45 degrees of bank with the same percentage margin above stall?

At 50 (still 10 MPH above 1g stall speed), the airplane feels a but mushy and control isn't as assured (a gust could be Very bad).

At 60 degrees of bank, if you are descending at a constant rate, wouldn't the 2g stall speed be the one that is applicable?

 

[Palmpilot]

Why in the world would anyone agree to such a thing? Just because the stall speed is higher in a 60 degree bank than a 45 or 30 why does that equate to higher risk? Is it because it is believed that stalls are somehow more sinister at high bank angles? In turns generally?

Perhaps I've been conditioned to think that way because some of the planes I fly have 60 degrees of bank as an operating limitation.

I would agree that the risk is higher for anything you're not skilled at that you might be trying for the first time in an emergency but that's a different point than saying 60 degree banks are inherently more risky.

Isn't it true that 60 degrees of bank requires a higher skill level than smaller bank angles?

 

[dmccormack]

I think that's a bit of a myth. If you're in a constant-rate descent, then your wing is necessarily generating all the lift needed to haul the plane around in an arc, and all the lift needed to carry the plane's weight. You may get a tiny bit of boost from a vertical component of drag, but it's not significant.
-harry

Then why does a 60 degree bank level turn feel 2 g while a descending 60 degree turn doesn't?

I'm sure the aerobatic types can tell us about "unloading" the wing. I've heard it discussed, read Rich Stowell's books, had it demonstrated, yada, yada.

http://www.apstraining.com/nose-high-unusual-attitude-recovery/

I *think* it means the airplane is in a semi or full free fall -- the wings are not providing lift momentarily, and thus there is no stress on them for the time they are unloaded.

Correction/ better development of this topic welcome!

 

[brcase]

Then why does a 60 degree bank level turn feel 2 g while a descending 60 degree turn doesn't?

I'm sure the aerobatic types can tell us about "unloading" the wing. I've heard it discussed, read Rich Stowell's books, had it demonstrated, yada, yada.

http://www.apstraining.com/nose-high-unusual-attitude-recovery/

I *think* it means the airplane is in a semi or full free fall -- the wings are not providing lift momentarily, and thus there is no stress on them for the time they are unloaded.

Correction/ better development of this topic welcome!

It is true the airplane should be accelerating(increasing descent rate) in the descent as the wing is unloaded and this might be for only a short period of time, however I think it is possible to get a lot of degrees of heading change in that short period of time.

Brian

 

[PittsDriver]

If we're talking about turning the airplane around faster and in in a smaller radius you're going to have to trade some vertical lift for horizontal lift and that results in an increase of the G load on the airplane. Anytime you do that, the direction of flight departs to a greater extent from the direction the wing is pointed increasing AOA for a given airspeed. Thus, the wing stalls at a higher airspeed and why you should have a mental model for stalls that isn't tied to a particular speed/configuration of the plane but rather the difference in where your energy has you traveling vs where the airplane's nose it pointed, i.e. angle of attack. That's a related but different discussion but hold that thought for a moment.

If your engine stops providing thrust and you roll the airplane into a 60 degree bank and hold 2 G, you'll do a level turn but you're probably not going to like where your airspeed is at the end of your turn if you can even complete it without stalling. So we trade altitude for speed. What's the right speed to look for on the ASI? Hell I don't know because I'm not in a 2G turn resulting from a level 60 degree banking turn. And if you don't have G meter in your airplane you're not going to know the exact stall speed for this descending maneuver either without some practice in your airplane (or maybe someone smarter than me will). I'd probably shoot for a speed around my best glide speed to hold. But if you have that mental model of the delta angle between direction of flight and direction the nose is pointed and a calibrated set of pants on that can feel the first signs of a stall buffet, you don't have to even look at the ASI during this maneuver. Just pull until the first signs of the buffet and then let just a tiny little bit of that load go.

The reason my first post in this thread was "way to go Dan." He's out calibrating the seat of his pants on how much to bank and how hard to pull before it starts breaking loose. Maybe he'll never in his life have to execute this maneuver for real but just practicing it will give him a greater feel for his airplane and is making him a more intuitive stick and rudder guy.

For all those that think this zen, seat of the pants stuff is crazy talk let me just say that the limits of your airplane are probably way out there beyond your comfort zone - that's certainly the case for me and my plane. Those limits are probably out there way beyond what you even this is possible. This is one of the great benefits of just a little aerobatic instruction. It's kinda like going out to a skid pad and doing some sliding turns in your car with a driving instructor. It'll make you more likely to do the right thing when you're sliding on ice someday. Same thing for airplanes with aerobatic instruction and owning a pair of calibrated airplane pants.

 

[Capt. Geoffrey Thorpe]

Then why does a 60 degree bank level turn feel 2 g while a descending 60 degree turn doesn't?

I'm sure the aerobatic types can tell us about "unloading" the wing. I've heard it discussed, read Rich Stowell's books, had it demonstrated, yada, yada.

http://www.apstraining.com/nose-high-unusual-attitude-recovery/

I *think* it means the airplane is in a semi or full free fall -- the wings are not providing lift momentarily, and thus there is no stress on them for the time they are unloaded.

Correction/ better development of this topic welcome!

In the original turn from the first post in this thread, you were accelerating as you turned. That's why the G loading was less. You weren't pulling hard enough to maintain a steady speed. If you are descending at a steady speed, the lift necessary is reduced by the function of drag and the sine of the descent angle, but for small angles that is, well, small. But if you are letting the nose drop and the aircraft accelerate the necessary lift (and thus, G loading) can be arbitrarily small. At least for a reasonably short period of time - which is what you did in your so called impossible turn.

G loading is a function air speed and angle of attack. Angle of attack is a function of how hard you pull. No pull, no G. Of course, gravity will modify your trajectory downwards...

 

[PittsDriver]

Perhaps I've been conditioned to think that way because some of the planes I fly have 60 degrees of bank as an operating limitation.

The limitation comes from keeping the airplane in a configuration that wouldn't require you to be wearing a parachute (according to the FARs). As long as you keep the airplane operating with it's G limits it doesn't care how much it's banked. While you should always respect how your airplane is "limited" those limits aren't aways placed there as a marker for increased risk to you or the airplane unless you count risk to your certificate for operating outside of them.

That's why I commented that it's more of an experience thing than an airplane physics problem.

 

[dmccormack]

I'd probably shoot for a speed around my best glide speed to hold. But if you have that mental model of the delta angle between direction of flight and direction the nose is pointed and a calibrated set of pants on that can feel the first signs of a stall buffet, you don't have to even look at the ASI during this maneuver. Just pull until the first signs of the buffet and then let just a tiny little bit of that load go.

Exactly -- there's a sense that "More nose down is waste of energy -- too much nose up is going to result in decaying speed. Let's try about here."

The ASI isn't really the director -- the sensation is -- the ASI confirms.

The reason my first post in this thread was "way to go Dan." He's out calibrating the seat of his pants on how much to bank and how hard to pull before it starts breaking loose. Maybe he'll never in his life have to execute this maneuver for real but just practicing it will give him a greater feel for his airplane and is making him a more intuitive stick and rudder guy.

Which is why I said in another post I've learned more stick and rudder in the past 50 hours in this Chief than I did previous 500. Of course it's an exaggeration, but the lack of finely calibrated gauges means that feel and view have to be better calibrated. This has absolutely translated back to my flying in larger, more modern SEL airplanes.

For all those that think this zen, seat of the pants stuff is crazy talk let me just say that the limits of your airplane are probably way out there beyond your comfort zone - that's certainly the case for me and my plane. Those limits are probably out there way beyond what you even this is possible. This is one of the great benefits of just a little aerobatic instruction. It's kinda like going out to a skid pad and doing some sliding turns in your car with a driving instructor. It'll make you more likely to do the right thing when you're sliding on ice someday. Same thing for airplanes with aerobatic instruction and owning a pair of calibrated airplane pants.

I did some emergency recovery type training with a local 10k hour-flown-everything-own-a-decathlon CFI. Before we flew I said, "Show me all the ways students may try to kill me."

Now that I own an airplane, it's incumbent on me to learn how to nibble at the edges of the envelope, and then learn how to recover.

It's fun!

 

[mantakos]

It is true the airplane should be accelerating(increasing descent rate) in the descent as the wing is unloaded and this might be for only a short period of time, however I think it is possible to get a lot of degrees of heading change in that short period of time.

Note that a fully unloaded wing is not only not providing a vertical component of lift, it's also not providing a horizontal component of lift. We need our wing to hold us up, but we also need it to change our course.

There's no free lunch here. You can lighten the wing's workload by making it do less, but then it's doing less of the thing you needed it to do in the first place, which in this case is pull the plane around in an arc while keeping it from tumbling out of the sky.
-harry

 

[Palmpilot]

Then why does a 60 degree bank level turn feel 2 g while a descending 60 degree turn doesn't?

Based on Newton's Laws, it seems to me that the only way that could happen is if you were executing the maneuver in such a way that your rate of descent was increasing throughout the duration of the turn. If that is indeed what you're doing, that would explain why you are getting different results than Rogers predicts, because his analysis is for the case of a constant rate of descent during the turn.

I'm sure the aerobatic types can tell us about "unloading" the wing. I've heard it discussed, read Rich Stowell's books, had it demonstrated, yada, yada.

http://www.apstraining.com/nose-high-unusual-attitude-recovery/

I *think* it means the airplane is in a semi or full free fall -- the wings are not providing lift momentarily, and thus there is no stress on them for the time they are unloaded.

Correction/ better development of this topic welcome!

As Harry pointed out, if you unloaded the wing completely (i.e., zero lift) the rate of turn would go to zero. Furthermore, if it weren't for drag, the rate of descent would increase at 32 feet per second per second. (You don't need aerodynamics to see that, only Newton's Laws.) In one second your rate of descent would increase by 32 feet per second, which equals 1920 fpm. After two seconds, it would have gone up by 3840 fpm. At some point the rate of descent will get high enough so that the vertical component of drag will become significant enough to limit your rate of descent. But since you're not turning, you're giving up all that altitude for no benefit.

If you unload the wing to 1g, then since the bank angle is 60 degrees you will have half the lift that would be needed for a constant rate of descent. Your rate of descent would increase at 16 feet per second per second until the vertical component of drag became significant, and you would turn, but not as fast as you would if you had done a 2g turn.

 

[bbchien]

Sigh. It boils down to this:
(1) Don't stall...you'll die.
(2) Practice with a 1000 foot additional floor. Don't stall.
(3) Fight like you practiced. Don't stall.

Did we forget to mention...."don't stall".

 

[ebetancourt]

I will apologize first. This thread is probably finished, and I should leave it alone. But more than most casual board discussions, this one has troubled me.

To add to Bruce's comment, the only thing worse than a stall close to the ground is a cross-controlled stall close to the ground. The comments about "altitudes" and practice at altitude all have their place. But if you leave the goal as the return to the runway, the stall and quite possibly the cross-controlled stall will happen when attempting to line up with the runway. If you practice this at altitude, please find a ground reference that approximates a normal runway, and pay attention to the winds at your selected altitude. Pay attention to the maneuvering required and ask yourself if you are comfortable doing that close to the ground.

My fear is that if you don't do that, you will convince yourself that you can do the turn back from X feet. Maybe even have a callout for yourself "X feet, I can turn back if I have to" or something of that nature. Then the real thing happens. The best case will be a teardrop return with a shallow reverse to the runway heading. The less good case will be a 270/90 course reversal. If there is a nice headwind on takeoff, when you make that 90 you will have a higher groundspeed than you are used to on short final. You may be attempting a turn below 100 feet and have a huge temptation to skid the turn so that you can achieve "alignment" while applying back pressure to achieve a "normal" groundspeed.

Please, always make your primary goal not stalling. If you line up fine, if you don't -- DON'T STALL.

I am done preaching and I apologize for doing so, but my conscience feels better.

Ernie

 

[dmccormack]

I will apologize first. This thread is probably finished, and I should leave it alone. But more than most casual board discussions, this one has troubled me.

To add to Bruce's comment, the only thing worse than a stall close to the ground is a cross-controlled stall close to the ground. The comments about "altitudes" and practice at altitude all have their place. But if you leave the goal as the return to the runway, the stall and quite possibly the cross-controlled stall will happen when attempting to line up with the runway. If you practice this at altitude, please find a ground reference that approximates a normal runway, and pay attention to the winds at your selected altitude. Pay attention to the maneuvering required and ask yourself if you are comfortable doing that close to the ground.

My fear is that if you don't do that, you will convince yourself that you can do the turn back from X feet. Maybe even have a callout for yourself "X feet, I can turn back if I have to" or something of that nature. Then the real thing happens. The best case will be a teardrop return with a shallow reverse to the runway heading. The less good case will be a 270/90 course reversal. If there is a nice headwind on takeoff, when you make that 90 you will have a higher groundspeed than you are used to on short final. You may be attempting a turn below 100 feet and have a huge temptation to skid the turn so that you can achieve "alignment" while applying back pressure to achieve a "normal" groundspeed.

Please, always make your primary goal not stalling. If you line up fine, if you don't -- DON'T STALL.

I am done preaching and I apologize for doing so, but my conscience feels better.

Ernie

All this presumes a pilot unfamiliar with the performance of his/her airplane within the flight maneuvering required to achieve the turnback.

The choice is simple: "Don't ever try this!" or "Experiment to find where the edges are."

If you choose the latter course, all the normal caveats apply -- instruction, altitude, practice, etc etc etc.

 

[rstowell]

I've never been able to track down this technical report, so I can't give much credence to the quote. I have to be skeptical that they had enough data to work with to come up with such statistics.

Not sure why you can't find that paper, but that doesn't mean it doesn't exist.

The number "62" appears nowhere in that report.

Neither does the number "68".

Easily calculated from the data provided in the report cited.

That's not true.

Then please enlighten us with the true margin for error when executing such a turn with the stall warning horn going off very close to the ground, with smoke in the cockpit and screaming passengers (and the elevated stress levels on the pilot that go along with that), executed by "average" pilots who are notoriously bad at maneuvering flight (according to AOPA ASF among others).

Which is a good argument for not practicing this close to the ground.

If it's so dangerous to practice close to the ground in a controlled environment with power available anytime the pilots wanted to abort, are you suggesting that the maneuver becomes less dangerous during a surprise, real-life engine failure on climb out?

Sure, because the simulator didn't simulate any trees or buildings to crash into. If the world ahead of you is a computer-generated runway of infinite width and length, then the runway behind you has nothing to offer that improves upon what's ahead of you, so by all means do land straight ahead.
-harry

When statistics continually show that impact speed and impact angle are the determining factors for crash survivability, what exactly do trees and buildings have to do with this discussion at all? In other words, evidence repeatedly points to the "how" of the arrival and not at all to the "where" of it. For example, see Clark, John C., “Summary Report on the National Transportation Safety Board’s General Aviation Crashworthiness Project Findings,” SAE Technical Paper Series 871006, 1987.

If the objective of learning to try to execute a turnback from a total engine failure on the upwind leg is the belief that the odds of survival for pilot and pax will be increased, that is demonstrably false.

If the objective is to save the airplane, that's a dumb reason.

If the objective has to do with the morals/ethics of possibly hurting "innocents" on the ground in populated areas, that's certainly a reasonable discussion to have provided a) you don't stall/spin into innocent B's house in the process of trying to avoid innocent A's house; b) you candidly brief your passengers on the course of action you are predisposed to take, and the high statistical odds that they could be killed as a result; and c) you've had the same candid discussion about the real odds with your loved ones.

Also, rather than trying to come up with unusual ways to demonstrate superior skills, how about instead we as a pilot community exercise the more mundane skills of ensuring that we've: 1) put fuel in the airplane; 2) are accessing that fuel; 3) have checked for contamination in that fuel; and 4) don't have carb ice on takeoff?

Those four pilot-controlled variables account for the overwhelming majority of causes of apparent engine failures. True mechanical engine failures are in the low single digits.

I think this thread is focusing on the wrong (and potentially more dangerous) thing here.

 

[mantakos]

Not sure why you can't find that paper, but that doesn't mean it doesn't exist.

No, it means that I can't see it for myself, verify what it says, and evaluate the methods by which their results were obtained.

Easily calculated from the data provided in the report cited.

Yes, by combining results that should never have been combined, such as mixing in results where the test subjects were explicitly told the _wrong_ technique, like skidding through the turn.

Then please enlighten us with the true margin for error when executing such a turn with the stall warning horn going off...

The margin of error for loss of control is chosen by the pilot. The optimal airspeed is just above stall, but there is no requirement to fly the maneuver with optimal performance.

... very close to the ground ...

When proper margin is applied to the turn-back altitude, the plane should be wings-level with several hundred feet below you. Note that there is no engine out option that doesn't involve "very close to the ground".

... with smoke in the cockpit and screaming passengers (and the elevated stress levels on the pilot that go along with that), executed by "average" pilots who are notoriously bad at maneuvering flight (according to AOPA ASF among others)...

Sounds like these conditions are not the result of the choice of maneuver, and will apply regardless of the choice. But if the pilot is not confident of his ability to accomplish such a maneuver, as demonstrated by practice, then he would do well to neglect it as an option.

If it's so dangerous to practice close to the ground in a controlled environment with power available anytime the pilots wanted to abort, are you suggesting that the maneuver becomes less dangerous during a surprise, real-life engine failure on climb out?

It would be unwise to practice this maneuver close to the ground when the option exists of practicing it at altitude.

There are many emergency maneuvers that are too dangerous to practice "for real", particularly when they are only required in response to highly improbable events, like an engine out on departure. Would you practice an engine-out landing into a field all the way down into the flare? If that's too dangerous to practice, does that mean that it's too dangerous to serve as an option in a real-life emergency? Of course not, the premise is silly.

When statistics continually show that impact speed and impact angle are the determining factors for crash survivability, what exactly do trees and buildings have to do with this discussion at all?

Because the impact angle varies significantly for a crash into a tree or building as compared to a glide onto a flat surface, due to the tendency of trees and buildings to rise at a perpendicular angle to the surface of the Earth.

If the objective of learning to try to execute a turnback from a total engine failure on the upwind leg is the belief that the odds of survival for pilot and pax will be increased, that is demonstrably false.

Then please supply us with that demonstration, it would be enlightening to us all. Do make sure that this demonstration assumes a pilot who is trained on the proper way to perform the maneuver, has practiced it, and has made the decision that he is prepared to do it. Also provide a demonstration of the odds of success for the alternate choices.
-harry

 

[gprellwitz]

Then please supply us with that demonstration, it would be enlightening to us all. Do make sure that this demonstration assumes a pilot who is trained on the proper way to perform the maneuver, has practiced it, and has made the decision that he is prepared to do it. Also provide a demonstration of the odds of success for the alternate choices.
-harry

Harry,
Maybe you can get Rich to post it on his website: http://www.richstowell.com/

 

[dmccormack]

I think this thread is focusing on the wrong (and potentially more dangerous) thing here.

I started this thread with a description of some attempts I made to do a 180 with power to idle to see how much altitude I lost: partly to test my technique, partly to test the airplane.

It has changed how I fly patterns. I begin the turn to crosswind sooner, and make one continuous turn (no squared off patterns).

But this is for a particular airplane at a specific airfield. My options straight ahead are very limited, the engine is 70 years old, and the airframe isn't designed for power-off flight.

So it is important for me to know ahead of time that there is no way I can make it back before I reach some altitude, and reinforce that once in a while.

Above that height it becomes possible, without unusual attitudes, skills, or maneuvers.

 

[Palmpilot]

The best case will be a teardrop return with a shallow reverse to the runway heading. The less good case will be a 270/90 course reversal.

"Less good" is quite an understatement. According to the analysis in the Rogers paper (which can be found through the link in post #20), for an example scenario discussed in the "Comparison" section on page 11, a 90/270 maneuver requires a runway about FIVE TIMES AS LONG as a teardrop procedure when the same bank angle is used for both.

Please, always make your primary goal not stalling. If you line up fine, if you don't -- DON'T STALL.

Agree 1000 percent!!!

 

[rstowell]

The margin of error for loss of control is chosen by the pilot. The optimal airspeed is just above stall, but there is no requirement to fly the maneuver with optimal performance.

I disagree, especially when the average pilot lacks the aeronautical knowledge and/or the skill set to be able to know what the margin for error is, much less "choose" it.

When proper margin is applied to the turn-back altitude, the plane should be wings-level with several hundred feet below you.

"Several hundred feet below" coupled with the usual 15-20 knot tailwind that would result on our 2700 foot runway will only result in hitting objects at the other end with more energy.

Would you practice an engine-out landing into a field all the way down into the flare? If that's too dangerous to practice, does that mean that it's too dangerous to serve as an option in a real-life emergency?

Not an equivalent situation. And yes, training scenarios such as you describe may indeed present themselves as favorable and safe to simulate an engine-out all the way down to a touchdown. For example, during a clinic I conducted in Fairbanks where the smaller GA runway and the ski strip are aligned, separated by a taxiway. We coordinated the following with the tower on a quiet morning: touch and go on the paved runway; simulated engine failure on climb out; nose down and glide straight ahead to a landing on the then-gravel ski strip; touch and go. But I would not simulate turnarounds from low altitude from simulated engine outs on climb out - ever.

Because the impact angle varies significantly for a crash into a tree or building as compared to a glide onto a flat surface, due to the tendency of trees and buildings to rise at a perpendicular angle to the surface of the Earth.

You're assuming the pilot is unable to point the nose between trees and shed the wings (thereby also taking away energy) or must center punch a building with no other options to maneuver even a few degrees one way or the other. Plus, buildings, cars, etc. typically do not result in the fatal sudden impacts/sudden decelerations that spinning into the flat ground surrounding an airport at a 60-70 nose-down angle do after botching a turnback.

Again, read the Crashworthiness study.

Then please supply us with that demonstration, it would be enlightening to us all. Do make sure that this demonstration assumes a pilot who is trained on the proper way to perform the maneuver, has practiced it, and has made the decision that he is prepared to do it. Also provide a demonstration of the odds of success for the alternate choices.
-harry

Now THAT's silly, Harry! You could pose that challenge to anyone about any maneuver with the same "who is trained on the proper way" caveats and get a favorable result. The problem isn't how a superbly skilled, highly current/competent pilot could perform, but how the vast majority of average pilots with average training and average skills not only will, but often do, behave.

Just because Sean Tucker or Patty Wagstaff or Bob Hoover can do what they can do with airplanes close to the ground shouldn't serve as a model for the rest of the aviation community to emulate. Nor should we talk in forums such as this as if those kinds of advanced skills are readily available to the majority of (i.e., average) pilots who are flying less than 100 hours a year.

For example, I can perform a one-turn spin and recover to level flight in a total of 400 feet in a Citabria, and could do the same consistently even below 1,000 feet agl, too (precisely where most stall/spin accidents occur). Give me 500 feet agl and I'll have 100 feet to spare in which to flare and land. In fact back in the day, one of my spin mentors used to perform a two-turn spin to a landing in an Aeronca C-3 as part of his air show act. But it would be irresponsible to suggest that because some of us can do some of these things, that it's easily attainable for everyone else out there if they simply tried it a few times. It takes far more repetitions to master such complex, dynamic, and corner-of-the-envelope maneuvers than average pilots will put into their training regimens.

Again, you're better off making sure you've done what you're supposed to do to fuel-wise and carb ice-wise before departing.

 

[brcase]

I started this thread with a description of some attempts I made to do a 180 with power to idle to see how much altitude I lost: partly to test my technique, partly to test the airplane.

It has changed how I fly patterns. I begin the turn to crosswind sooner, and make one continuous turn (no squared off patterns).

But this is for a particular airplane at a specific airfield. My options straight ahead are very limited, the engine is 70 years old, and the airframe isn't designed for power-off flight.

So it is important for me to know ahead of time that there is no way I can make it back before I reach some altitude, and reinforce that once in a while.

Above that height it becomes possible, without unusual attitudes, skills, or maneuvers.

Dan, in my opinion you have this exactly right. In most aircraft, certainly not all,turning crosswind at 500 feet, once you get to 90 degrees of turn at 500 feet the turn back to runway is no more difficult than doing it from downwind. This does assume about a 5000 foot runway, and a normal climb out.

But if you don't know what you can do, certainly don't try in an emergency situation. My Motto for emergency landings is "make them much like your normal landing as possible, try as little new stuff as possible during an emergency."

Brian

 

[mantakos]

I disagree, especially when the average pilot lacks the aeronautical knowledge and/or the skill set to be able to know what the margin for error is, much less "choose" it.

The pilot lacks the knowledge and skill to be able to choose an airspeed?

"Several hundred feet below" coupled with the usual 15-20 knot tailwind that would result on our 2700 foot runway will only result in hitting objects at the other end with more energy.

Should I ignore the possibility of a turnback as an option when I'm flying in a steep climber from a 6000' runway because you can imagine the existence of a plane that, in conditions you can imagine, cannot land at a 2700' runway that exists somewhere else? Should I be basing my emergency procedure strategies on this kind of logic?

Not an equivalent situation.

You tried to argue that if something is too dangerous to practice, then it's too dangerous to be an emergency procedure. This is clearly a false assertion. We don't practice engine outs by shutting down the engine, we don't practice off-airport landings down to the flare, we don't practice stall recovery at low altitude, and we don't exactly have the opportunity to practice using trees to shear off the wings...

But I would not simulate turnarounds from low altitude from simulated engine outs on climb out - ever.

Nor should you, nor should anybody advocate this.

You're assuming the pilot is unable to point the nose between trees and shed the wings...

Sure, if the trees place themselves in such an accommodating fashion, and if the aim is good enough, what with the cockpit full of smoke, the passengers screaming, the elevated stress levels, and the pilot notoriously bad at maneuvering flight...

Plus, buildings, cars, etc. typically do not result in the fatal sudden impacts/sudden decelerations that spinning into the flat ground surrounding an airport at a 60-70 nose-down angle do after botching a turnback...

So I guess the only two choices are perfect execution of a "straight-ahead" maneuver vs complete loss of control for a "turn-back" maneuver? Doesn't this strike you as a disingenuous argument?

The pilot needs the ability to do a power-off gliding 180 with a 45 degree bank and a speed a small margin above stall, a maneuver very similar to a comm power-off steep spiral. If his skill is inadequate for this, as demonstrated by his practice attempts, then he should not add this to his bag of tricks, nor should he consider it without this practice.

The problem we have is that pilots are not trained in this maneuver, and so they attempt it in situations where success is not a possibility, and they attempt it using techniques that are incorrect. We see this and instead of saying "we should educate pilots", we say "that maneuver is dangerous, we better avoid ever saying anything about that maneuver to pilots, because it will give them ideas". Then we take it upon ourselves to preach the gospel ("thou shalt not turnback, it is an abomination").

Sorry, but I don't buy into this gospel, and certainly don't buy into selling dishonest arguments with dubious abuse of statistics, rationalized by the belief that my cause is just and good.

Now THAT's silly, Harry! You could pose that challenge to anyone about any maneuver with the same "who is trained on the proper way" caveats and get a favorable result. The problem isn't how a superbly skilled, highly current/competent pilot could perform, but how the vast majority of average pilots with average training and average skills not only will, but often do, behave.

Is it your assertion that it is "demonstrably" true that only a superb pilot is capable of flying a 45 degree bank at an airspeed a small margin above stall? Shouldn't pilots attempt the maneuver at altitude and evaluate their demonstrated skill for themselves, and choose their strategies accordingly?
-harry

 

[PittsDriver]

You could pose that challenge to anyone about any maneuver with the same "who is trained on the proper way" caveats and get a favorable result. The problem isn't how a superbly skilled, highly current/competent pilot could perform, but how the vast majority of average pilots with average training and average skills not only will, but often do, behave.

I'm confused then because it looks like we're in agreement that if you "trained on the proper way" you'd get favorable results. Rich, you of all people know that a lot training is installing a programming that can be invoked when it hits the fan. Why would you argue against these training exercises given the remark you made quoted above?

Maybe you can point out the flaw in this reasoning?
1. Pilots will attempt this maneuver with no previous effort to master it - often to a bad result. The lure of that runway is strong.
2. There are many cases when this turn just won't work well.
3. There are cases when it would be well within the skills of the average pilot with training to perform a turn-around with a high degree of success - and that is demonstrable though maybe without the smoke and screaming from the back seat.
4. For pilots to develop the judgement to make this decision on the fly, training would be essential.

No one is suggesting that you should have to perform this maneuver to get a private cert but you and I both know that pilots need better stick and rudder skills and judgement than is taught by the primary training they get. Shouldn't pilots aspire to this level of skill and shouldn't there be competent instructors that know how to teach something other than rote numbers and rules of thumb? Isn't that how you make your living?