Impossible Turn Testing

[FlyingMonkey]

I'll disagree here.

In the case of the "Impossible Turn", the biggest danger is rushing the turn with rudder at low speed. It's so instinctive that even experienced pilots fall victim to it. So, "if it doesn't work out" often means that part way through the turn, the inside wing drops precipitously as the plane enters a spin.

At that point, it's unlikely that one could have the presence of mind - and time - to pull the chute.

This could likely be the very last thing one saw, with only a few seconds to decide, reach for and pull the chute - which itself takes a finite amount of time to deploy.

Not saying it's "impossible", but I think it's a dangerous assumption to think on an engine failure on climbout one will have the time and mental capacity to sort through things and try them sequentially

To avoid repetition, there's a very long thread on this very topic on Pilots of America, where I've weighed in.http://www.pilotsofamerica.com/forum/showthread.php?t=76880

Of course all of this is the danger here. THIS IS A HIGH RISK MANEUVER.

 

That said, I'm not sure the right lesson from what you posted is "never attempt the turn"...I would say a better lesson is "if you feel the need to do this, make sure the airplane stays coordinated throughout the maneuver, and resist the impulse to skid the turn." And my notion that you can still pull the chute if it does not work out is valid. Even in a stall/spin, if you plan that if at any point a wing drops in the maneuver you pull the handle, you are ready for it and can likely deploy the chute before the spin develops.

 

Yes, this is all really hard to do under stress. But we are talking about a more or less "do or die" scenario here, you have to get it done right, even if you land straight ahead. Going straight does not guarantee you won't stall stretching the glide, you have to be aware of that danger and resist it.

 

Going straight or using the BRS are usually going to be the safest options, but I think you should have this capability in your bag 'o tricks in case circumstances favor it.

[AZAV8OR]

There are two aspects to a turn, radius and rate.  The radius in this case doesn't matter too much, as in a CT the radius of turn in the impossible turn scenario will not be too much different between 60kt and 80kt.  The RATE of turn (how many degrees per second you can push the nose around the circle) you can sustain with higher speed is greater.  if at 80kt you can keep a 1.8g turn, and at 60kt you can do a 1.5g turn (without stalling) then you are going to make the turn around faster at 80kt.

 

Of course, with a dead engine you are making no thrust and any speed you have decays.  If the engine quits at 80kt, I am going to be able to pull a tighter sustained turn until that speed bleeds off to my "safe" target speed of 60kt than if I wait to make the turn until 60kt, not to mention that as the speed falls I'm traveling farther from my desired landing with no way to recover the energy lost.

 

Now, you could let the nose drop low enough that your speed would stay at 80kt and turn really tight, but that 80kt is above the best L/D ratio of the CT, which is IIRC ~62kt at 15° flaps.  So doing that would make for a quick turn, but you are burning a lot of altitude to do that, and you will likely come out of the turn faster but not have enough glide to get you to the landing zone.

 

I'm not advocating making a turn faster than 60kt; but if the engine quits at 70kt or 80kt, don't wait to make the turn.  Get the nose down and make your turn, just let that extra speed bleed off in the turn and stabilize the turn when you get to ~60kt.  That speed will give you the best distance to glide (at 15° flaps) once you come out of the turn and the best chance to get to your landing zone.

 

Fighter pilots use this all the time, it's what they call an "angles fight".  You don't really care how big your turn is, you care about how many degrees per second you can generate to point your nose on the enemy (or at your landing zone).  The same principle really applies in real dogfights, as airplanes always run out of energy before they run out of maneuvers that the pilots would like to make, so they have to maximize them.  

 

This is IMO of course and YMMV, void where prohibited by law.

Ah so! Makes sense!

[AZAV8OR]

I agree with you, but it's all about having options.  If you never practice the turn, you have no idea how it might work out, so you have to take that option off the table, leaving only landing straight ahead or the BRS.  But if you have 800' AGL when the engine dies, there is no reason not to make that turn, it's plenty of height.  Even if it doesn't work out, you will know if well before you are outside the BRS deployment envelope, and you still have that option.

 

Imagine a far-fetched scenario.  You are taking off from the Mt. Gonnakillya airport, where the runway departure hangs on the edge of the basin of this giant volcano filled with molten lava.  If your engine quits on takeoff, you can't land straight ahead (remember, lava) and you can't use the BRS (again...lava).  Your ONLY option is to turn back.  

 

Granted that is a silly scenario, but it's not so hard to imagine a scenario where terrain or other circumstances dictate your best option for survival might be knowing how and when to use the impossible turn. 

All good points. As a matter of rule, I try to stay away from volcanos, though!

[FlyingMonkey]

All good points. As a matter of rule, I try to stay away from volcanos, though!

That is definitely an aviation "best practice."

[Tom Baker]

You have to pull the stick back to pull more g's.  Steep banks without backpressure will put you in a slip and not on the edge of a spin so at least it is error in the right direction.

A steep bank without backpressure does not have to put you in a slip. Go out and practice some Lazy 8's, not the dumbed down commercial and CFI PTS versions but some with a little steeper bank angle. You will see that you can have a steep coordinated bank angle without backpressure.

[FastEddieB]

Again, to avoid repetition my position is pretty well laid out in the thread on POA I linked to before.

[Ed Cesnalis]

A steep bank without backpressure does not have to put you in a slip. Go out and practice some Lazy 8's, not the dumbed down commercial and CFI PTS versions but some with a little steeper bank angle. You will see that you can have a steep coordinated bank angle without backpressure.

 

Your right, IOW if I lead with a steep bank and now back pressure it is easy to do either.  I follow with less rather than more rudder if I want to slip, which is the side I want to error on here as opposed to skidding.

[Tom Baker]

Again, to avoid repetition my position is pretty well laid out in the thread on POA I linked to before.

What little I have looked at the POA forum I have no desire to participate, and I rarely follow links listed in post.

[FastEddieB]

What little I have looked at the POA forum I have no desire to participate, and I rarely follow links listed in post.

Fair enough.

 

Two of my posts there:

 

1. Purely a thought exercise, since the dead don't talk, but...

 

I wonder if you could ask, let's say, 100 or 1,000 pilots who failed to make the impossible turn, "What were you thinking?" if a pattern would result.

 

Most popular?

 

"I had tried it so many times at altitude, I could have SWORN I could do it."

 

"I totally KNEW I would never attempt it, but something clicked and the siren song of the runway took over."

 

"I dunno. Just seemed like a good idea at the time."

 

Any other candidates?

 

And does anyone know of any account of a failed impossible turn survivor? That might be interesting, though probably not many of those around.

 

2. Just a data point...

 

...I don't recall ever having done "The Impossible Turn" scenario.

 

Maybe in the distant past I was shown it, but that was mainly to show what a bad idea it was.

 

I also don't think I've ever made a point of demonstrating one, except perhaps, again, to reinforce that its a BAD idea and not to be considered as an immediate consideration. What I wanted to see was a turn of not more than about 45º to select the least bad spot to land the plane under control. Only then, with sufficient altitude and things calmed down, to maybe consider a medium turn back towards the airport environment.

 

I'm not saying that that is right or wrong, just my recollection as a pilot trained in the 1970's.

[FlyingMonkey]

So Eddie, is your position "never, there is no altitude or distance from the runway where a 180 back to the runway can be made safely?"

[FastEddieB]

So Eddie, is your position "never, there is no altitude or distance from the runway where a 180 back to the runway can be made safely?"

No.

 

I've used the example of Knoxville, but any long runway would do.

 

I could be 1,200' or more and still be over the runway. Engine stops? Establish glide speed and turn downwind and fly a near normal pattern.

 

But at 800', I would strive to turn no more than about 45° and look for the least bad option off airport. If I was still high and close, I might establish a turn back to the runway environment, but do it gently and deliberately.

 

I just don't want a return to the airport to be a first reflex - that's what I think gets lots of pilots killed.

[IrishAl]

I'm surprised at your (Eddie's) position on this.

 

We all agree that it is properly named 'The Impossible Turn' at 200 feet, but at 1000 feet, it's no longer impossible - it's now the 'Very Possible Turn'.  And for some, it might be The Completely Certain Turn at that height.  

 

I can't understand why you still treat it as The Impossible Turn at 800', as you state in your last post.

 

The POH for the Ikarus C42 states the following, under the heading 'LOSS OF ENGINE POWER DURING TAKE OFF'

           

       'Do not attempt to return to airfield if altitude is below 260ft (80m) after gliding speed has been reached.  At lower altitudes, it         is best to land straight ahead without attempting any course corrections.'

 

(I was very surprised to find this, and I'm fairly sure the USA distributor would insist on it being removed!  It seems a very slim margin, doesn't it?)

 

However, this information does suggest that it is quite possible to turn 180 (and maybe backtrack a bit) with an overall drop of 260ft from a best glide starting position.  

 

My point is, Eddie, why not practice this turn starting at a safe height and as you get the familiar with doing it, bring it down further and further until you find your comfortable 'no turn back' height?   

 

It seems to me that most accidents in this phase of flight happen because a panicked decision is made due to the pilot having little or no personal experience of the situation to call on when his engine quits unexpectedly.  Surely such practice will help the pilot keep a cool head and deal with the event in a calmer way?

 

It would seem to me that this is a better solution than just taking a good, hefty safety margin and adding a load more to be extra sure?  

 

However, I stand to be corrrected!

[FastEddieB]

Maybe I didn't make myself clear.

 

At 800', after choosing an off airport site within about 45°, I might then consider a further turn back to the airport environment.

 

If I'm recalling correctly, at the approved school I taught at there was nothing in the syllabus about returning to the airport after an engine failure on upwind. I know it's not in the Practical Test Standards for any rating I'm familiar with. Why? The statistics seemed to point to the fact it was safer to continue straight ahead or nearly so.

 

The FAA tended to frown on attempting to return to the airport. Their Flight Training Handbook still says this:

 

"In the event of an engine failure on initial climb-out, the pilot’s first responsibility is to maintain aircraft control. At a climb pitch attitude without power, the airplane will be at or near a stalling angle of attack. At the same time, the pilot may still be holding right rudder. It is essential the pilot immediately lower the pitch attitude to prevent a stall and possible spin. The pilot should establish a controlled glide toward a plausible landing area (preferably straight ahead on the remaining runway)."

 

And that's what we taught.

 

If someone was taught "The Impossible Turn" and stayed proficient in it with constant practice, it could be a valuable tool - and maybe a lifesaver.

 

But in the heat of battle, a large number of pilots who thought they could do it have stalled and spun and died when a landing straight ahead very well could have been survivable.

 

But I'm not telling anyone what to do it not do. If you want to practice it, fine. It's not "impossible", so it may just work.

 

Or not.

[Ed Cesnalis]

Maybe I didn't make myself clear.

 

At 800', after choosing an off airport site within about 45°, I might then consider a further turn back to the airport environment.

 

If I'm recalling correctly, at the approved school I taught at there was nothing in the syllabus about returning to the airport after an engine failure on upwind. I know it's not in the Practical Test Standards for any rating I'm familiar with. Why? The statistics seemed to point to the fact it was safer to continue straight ahead or nearly so.

 

Anyway, I never learned it nor did I ever teach it.

 

If someone was taught it and stayed proficient in it with constant practice, it could be a valuable tool - and maybe a lifesaver.

 

But in the heat of battle, a large number of pilots who thought they could do it have stalled and spun and died when a landing straight ahead very well could have been survivable.

 

But I'm not telling anyone what to do it not do. If you want to practice it, fine. It's not "impossible", so it may just work.

 

Or not.

 

Things have changed.

 

I have always been open to returning to the field because my first 350lb Challenger permitted it, not because of a good glide ratio but because of an extremely steep climb gradient.  

 

If I compare my CTSW to the various heavier aircraft that I have flown, aircraft more similar to what you have taught in I find 2 distinct improvements.  

1. Much steeper climb gradient.
2. Improved glide ratio.

I'm now in a different performance class than I was with the Cessna or Piper.  I don't need as much altitude and I can get close to that point by the end of the runway.

[FastEddieB]

Things have changed.

 

 

I'll accept that.

[FlyingMonkey]

 

I just don't want a return to the airport to be a first reflex - that's what I think gets lots of pilots killed.

 

I agree with that!

[Jim Meade]

Lots of pilots killed? How many is lots? How many are killed doing the turn versus the number who would be killed with some other maneuver?

 

Some seem to prefer to work with facts and some prefer aphorisms. When we're done with this topic we can go on to spin training versus no spin training.

[Jim Meade]

I am rather busy and so am not doing the subject justice, but I think there is a lot of bad, even dangerous, discussion.

 

Here are a few references:

1. Naval aviation study, very well publicized. Read the entire article.

http://jeremy.zawodny.com/flying/turnback.pdf

 

The conclusion:

 

"A simplified model of the turnback maneuver after engine failure during the take-off climb

segment has been developed. The model shows that optimum conditions for returning to the

departure runway result from climbing at Vymax

max , executing a gliding turn through a 190°

heading change, using a 45° bank angle at 5% above the stall velocity in the turn using a

teardrop shaped flight path"

 

2. Barry Schiff, well known aviation author, in AOPA:

http://www.aopa.org/News-and-Video/All-News/2010/November/13/Turn

 

"Schiff suggests practicing the turn, performing it with an instructor, and considering the options.

Establish the aircraft in a stabilized climb at V y.

Retard the throttle.

Do nothing for 5 seconds and hold the nose in climb attitude.

Roll the aircraft into a 45-degree banked turn and maintain best glide speed.

Continue the turn until the heading has changed by 270 degrees.

Roll out of the turn.

Simulate a moderately aggressive flare for a landing.

Note altitude when vertical speed becomes zero.

Subtract this altitude from the altitude at which you retarded the throttle.

The minimum turnaround altitude should be increased by 50 percent.

Do not consider turning around unless two-thirds of the final turnaround altitude has been reached when passing over the departure end of the runway.

 

While presenting the checklist for performing a turn after takeoff, Schiff admonished that he was not recommending the maneuver, but suggesting pilots be prepared for the possibility. —Julie Summers Walker"

 

Jay Hopkins posits that human factors argue against the turn:

http://www.flyingmag.com/technique/proficiency/human-factor-big-push-improbable-turn?page=0,1

 

Sparky Imeson, author of "Mountain Flying Bible" talks about canyon flying. In this case, unlike the turn, the plane may be wanted to fly level. We all know that Imeson died in mountain flying. We don't know how.

 

Let's keep in mind that the turn would be descending. Talk about G forces need to keep in mind that the aircraft is in a fairly steep descent. (Aerodynamics for Naval Aviators talks about rate of turn, p 178 ff.)

 

For a constant airspeed, a greater angle of bank equates to a smaller turn radius and a greater turn rate. For a constant angle of bank, a slower airspeed will result in a smaller turn radius and a greater turn rate. APH 3-10. In the turn under discussion, the angle of bank would be constant (about 45° based on above recommendations) and the speed would become pretty constant (about 1.05 X Vs0) as soon as stabilized.

 

As a glider pilot, I've been trained to do a 180° turn back at altitude over 200'. I have personally done one at an altitude of 250' at runway 24 at MUT Muscatine, IA. I released from tow approximately over the end of the 5500' runway and immediately initiated a steep turn to the left. I don't know the altitude when I leveled off over runway 6, but I had to use full spoilers to feel comfortable getting down with the tailwind. Schiff remarks that an airplane with no engine is a glider - perhaps an inefficient one, but still a glider.

 

One thing I'm struck with is the difference in attitude toward training by casual versus professional pilots. Pilots flying charter or for the airlines expect to train regularly and expect to have to maintain certain standards and they receive training from objective trainers. Training for the turnback is not something they would find unusual if it were expected of them. (It's probably safe to say no one but Tex Johnson would seriously consider doing the turnback in an airliner at the kind of altitudes we're discussing here.) My point is that these kinds of pilots would have developed and practiced a profile that would give a high probability of success. Casual pilots see willing to go with old wives tales and hangar talk rather than the kind of training that is not only feasible but reasonable. Although, I'll admit that the very pilots who refuse to train for the turnback are also unlikely to train for a landout straight ahead, they just default to thinking that is their main option but do nothing to prepare themselves for it.

 

Maybe the discussion ought to be about departure incident training in general, not whether or not an untrained maneuver will be successful.

[IrishAl]

Thank you for your well-considered and concise input.

 

Very helpful!

[FastEddieB]

Jim,

 

Nice analysis - thanks.

 

To add to the knowledge base, I typed "FAA impossible turn" into Google and came up with this publication:

 

http://www.cfidarren.com/p8740-44.pdf

 

I don't know that never read that particular document, but I think it pretty well summarizes what I was taught 40 years ago, and what influenced my teaching, and personal decision making, over much of that 40 years.

 

I suggest everyone absorb as much information on the topic as possible, then make their own decisions as to the feasibility of a successful return at different altitudes. And if you're going to practice it, do it often enough to stay proficient.

[coppercity]

Good articles, thanks for sharing.

[Jim Meade]

I think the Darren article is fraught with the very type of misinformation we have seen in our discussion. A couple of points:

 

1. He talks about a standard rate turn, which is 3°/sec, or, for most light planes, about 15° bank. That is far too shallow a turn, according to any of those who have studied it (e.g. the Naval study I referred to).

 

2. He cites the increased g loading and stall speed in a steep bank. That is true only when holding altitude. We are decidedly in a steep descent in the turnback maneuver so all those level flight figures are not only inapplicable but misleading.

 

3. He eventually conceded that a more dramatic turn at a higher altitude could result in a turnback, but then he quibbles about the landing. A straigh-ahead off-airport landing may be just as challenging but he doesn't talk about that.

 

4. He says one reason people may want to turn back is they don't like to be told what to do - they don't want to have to listen to the advice of their betters, so to speak. It seems to me that a pilot who is trained and prepared may choose the optimum course of action as opposed to following "conventional wisdom" that is not supported by science..

 

Now, after the author makes his points, he offers suggestions that if the loss of power is at 200', land straight ahead. If at 400 feet, land within a 60° arc of straight ahead. I don't think any of us would suggest that a person try a turnback that is not possible. If a pilot has trained and is current and those numbers make sense there is no reason to not follow them. Not a single one of us is suggesting a turnback that we know won't work or that is marginal.

 

What those of us who consider a turnback advocate is to train and know your airplane, your environment and yourself and make a good choice. To me, the good choice is probably not "never turn back".

 

Maybe I am unfair to Ed, but what I hear him say is never turn back.

[Ed Cesnalis]

Looking at the Darren figure 1

 

 

 

The failure point is far enough beyond the end of the runway to complete a tear drop before getting back.  In my CTSW that is pattern altitude not 300' that he gives you to work with.

 

No doubt there are a few, although very few, situations in which circumstances might dictate turning back. But, such decisions, demanding split second action and supreme skill, are beyond the capabilities of the average pilot.

 

I flew for years with a 2-stroke and always had a glide to a field.  IMO Darren loses a lot of credibility with his scare mongering.

[Ed Cesnalis]

If you believe it would kill us why would you dare us to do it?

 

Aviators should look out for each other.

[Duane Jefts]

Hmmm, takeoff with 10 kt headwind on 6000 ft runway and climb to 500 ft a little ways past the departure end of the runway, lose engine, turn back with 10 kt tailwind - oops, may be a little high on final.

 

My point is - know your airplane, know your limitations, know your level of proficiency, don't presume to tell other folks what their abilities are or are not. 

 

We all have a different level of expertise, know yours, and stay within your limits.