Pivotal altitude. Why it matters...

[brcase]

A Question I like to ask when doing flight reviews is...

We start teaching Inadvertant Spin Avoidance almost from Lesson #1. Why or What Factors lead pilot to continue to have Stall Spin Accidents?

There obviously are a number of factors, but pivotal altitude is one of them, and often we don't even talk about it until we start teaching 8 on Pylons for the Commerical Check Ride.
And even then a I bet a lot of commercial pilots still haven't made the connection between pivotal altitude and low altitude spins.

Here is Quote from a article I was reading today...

Pivotal altitude.​

pilots do this maneuver for their (commercial) check rides, and it is to understand the height and speed combination as you sight down your wingtip as it should look like it is staying on one point, the wingtip not tracking forward or aft of that ground reference point. We spend all day watching our wing going backward (when turning). Once we get below pivotal altitude, the wing looks like it is going forward. This can lead to wanting to apply more rudder into the turn. For a more in-depth explanation of pivotal altitude check out the Airplane Flying Handbook.

When you are low, you get a sense of ground rush and might try to slow down.
(Credit to Garret Willat)

The take away, is what everyone knows, especially below pivotal altitude pilot need to be especially aware of maintaining Airspeed and Coordinated turns, as the desire to inadvertently Slow Down and Skid a Turn is much higher than at higher altitudes. But what not all pilots may yet appreciate is that below the pivotal attitude we should also be more alert for indications of a stall and prepared to recover at the 1st indication of a stall, especially while performing activities that might be distracting, emergency procedures for example. Also the pivotal altitude becomes higher the faster your ground speed i.e.. Downwind Turns.

Brian
CFIIG/ASEL

 

[farangutan]

I had three instructors during my commercial training. The third one really centered the importance of pivotal altitude in the 8s on pylon. The others really were teaching two adjacent turns around a point. I wish I had learned about it earlier in all my training because it really is important for all pilots.

 

[Domenick]

Eights on Pylons and pivotal altitude is also discussed in the free FAA Airplane Flying Handbook, page 7-14 in the current edition. Can also be found in the document by searching for "pivotal altitude." There is a handy chart.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook

 

[iamtheari]

For the fellow math nerds ...

 

[noahfong]

I'm sorry but you'll have to do a lot better to convince me. I'm not even sure whether I follow any of the logic or know how you and the article are connecting spins to pivotal altitude. If you're saying that a pilot will just pull back and stall the aircraft because the wingtip appears to go forward.... I think that's a stretch. But I'm open to more discussion.

 

[brcase]

I'm sorry but you'll have to do a lot better to convince me. I'm not even sure whether I follow any of the logic or know how you and the article are connecting spins to pivotal altitude. If you're saying that a pilot will just pull back and stall the aircraft because the wingtip appears to go forward.... I think that's a stretch. But I'm open to more discussion.

Have you done the eights on Pylon Maneuver? most pilots learning the maneuver have to resist the urge to use the rudder to just point the wing where they want it, since it supposed to be a coordinated manueuver.

Below Pivotal Altitude, the wing doesn't appear to pivot backwards like it does at higher altitudes. Slight above pivotal altitude it will appear to pivot slower than expected. So if a pilot is trying to turn quicker and make the turn look "normal" they may push on the rudder to Skid the turn, especially if they are leery of steepening then turn.

Of course that is just one piece of the stall spin puzzle. Another is the illusion of speed, downwind and closer the ground provides yet another illusion that the airspeed is faster that it really is, allowing a pilot to think it is fine to raise the nose, which might seem like a good idea when they see the ground or obstruction in front of them.

Add some more factors like a distraction and the we are starting to put a lot of pieces of a potential accident chain together.


Brian
CFIIG/ASEL

 

[Daleandee]

FWIW,

 

[noahfong]

Have you done the eights on Pylon Maneuver?

Of course I have. I know what 8s on pylons is. But it doesn't mean I automatically agree. I'll concede you may have a point... but I don't agree (yet) it's a significant one. Thanks.

 

[midwestpa24]

Its an interesting theory, a connection I have never heard made before. I would surmise it may be only one piece of a more complicated puzzle.

Another consideration, when we are practicing stalls and maneuvers of all kinds, we are usually at altitude. Our ground references are distant enough that you don't see small deviations in position like you do 300-400 feet off the ground in close reference to the runway threshold. Even at 1,000 feet, being laterally offset by 50 feet would be unnoticeable and would not be corrected. On short final that means you are lined up on the grass and you need to correct it. Add in the optical illusions, including what you are trying to point out in pivotal altitude, the reduction in safety margin due to low altitude and low airspeed, the urge to correct lineup without overbanking, etc, etc, it can all equal a bad situation with small margins between safe recovery and disaster.

 

[RyanShort1]

I think a bigger cause relates to the law of primacy and that most instructors rush past the “effects and use of controls” phase when they are trying to push a student to solo.

I’m not discounting the pivotal altitude argument, but we don’t teach that until commercial maneuvers. It’s not “that” foundational.

 

[Roger Wilco]

Count me in with noafong and RyanSHort1 on this. I'm curious: is there a real-world situation in which a pilot maneuvers the airplane by pinning a wingtip reference point to a point on the ground while turning?

I was taught, and subsequently taught others, how to perform 8s on Pylons in a part of the country where 15-20kt winds were common. It was one of several ground reference maneuvers that demonstrate the effects of wind, and proper use of controls. Other than that, I've never found any practical value.

 

[MauleSkinner]

Count me in with noafong and RyanSHort1 on this. I'm curious: is there a real-world situation in which a pilot maneuvers the airplane by pinning a wingtip reference point to a point on the ground while turning?

I was taught, and subsequently taught others, how to perform 8s on Pylons in a part of the country where 15-20kt winds were common. It was one of several ground reference maneuvers that demonstrate the effects of wind, and proper use of controls. Other than that, I've never found any practical value.

or…photography.

 

[Roger Wilco]

[AC-130]

or…photography.

Well, there's one I hadn't considered: blasting evildoers to shreds. Have you flown that mission?

As for photography, of the not-too-many aerial photo shoots that I have flown, the camera operator was more concerned about maintaining a steady platform and a constant altitude. Admittedly, my experience is limited.

 

[MauleSkinner]

Well, there's one I hadn't considered: blasting evildoers to shreds. Have you flown that mission?

As for photography, of the not-too-many aerial photo shoots that I have flown, the camera operator was more concerned about maintaining a steady platform and a constant altitude. Admittedly, my experience is limited.

No, haven’t blasted evildoers.

I flew a guy who took photos of farm sites, but the best angle was below pivotal altitude, so there was a lot of slipping and skidding to point the wing, and he’d say, “wing up” when he wanted me to raise the wing out of his shot.

 

[RyanShort1]

Well, there's one I hadn't considered: blasting evildoers to shreds. Have you flown that mission?

As for photography, of the not-too-many aerial photo shoots that I have flown, the camera operator was more concerned about maintaining a steady platform and a constant altitude. Admittedly, my experience is limited.

I’ve flown photography for a decade. Pivotal Altitude is not part of our mission. In fact, we want to maintain a constant altitude - so flying PA would be quite negative for us.

 

[Skymac]

ATP/CFII/MEI/IGI with about 2000 hours dual given, you’ll never convince me that 8’s on pylons and pivotal altitude is anything more than rubbish… I believe it’s one of the most useless things that’s required of the ACS. I could think of many more relevant items to take its place.

We all have opinions though.

 

[kgruber]

Mattered in Vietnam with "Puff the magic dragon!"

 

[RyanShort1]

Mattered in Vietnam with "Puff the magic dragon!"
View attachment 123585

I genuinely doubt that.

 

[LoLPilot]

View attachment 123546

or…photography.

First of all thanks for this thread. I am currently practicing and studying for my commercial and this is super interesting. I'm going to check the videos out, but is there a link to the original article?

Also, while practicing 8's on pylons with my instructor, once we were established on the first pylon I was like "gunner... light 'em up." My CFI was like "well okay then."

 

[Clip4]

A Question I like to ask when doing flight reviews is...

We start teaching Inadvertant Spin Avoidance almost from Lesson #1. Why or What Factors lead pilot to continue to have Stall Spin Accidents?

There obviously are a number of factors, but pivotal altitude is one of them, and often we don't even talk about it until we start teaching 8 on Pylons for the Commerical Check Ride.
And even then a I bet a lot of commercial pilots still haven't made the connection between pivotal altitude and low altitude spins.

Here is Quote from a article I was reading today...

Pivotal altitude.​

pilots do this maneuver for their (commercial) check rides, and it is to understand the height and speed combination as you sight down your wingtip as it should look like it is staying on one point, the wingtip not tracking forward or aft of that ground reference point. We spend all day watching our wing going backward (when turning). Once we get below pivotal altitude, the wing looks like it is going forward. This can lead to wanting to apply more rudder into the turn. For a more in-depth explanation of pivotal altitude check out the Airplane Flying Handbook.

When you are low, you get a sense of ground rush and might try to slow down.
(Credit to Garret Willat)

The take away, is what everyone knows, especially below pivotal altitude pilot need to be especially aware of maintaining Airspeed and Coordinated turns, as the desire to inadvertently Slow Down and Skid a Turn is much higher than at higher altitudes. But what not all pilots may yet appreciate is that below the pivotal attitude we should also be more alert for indications of a stall and prepared to recover at the 1st indication of a stall, especially while performing activities that might be distracting, emergency procedures for example. Also the pivotal altitude becomes higher the faster your ground speed i.e.. Downwind Turns.

Brian
CFIIG/ASEL

I agree PA is an important concept for emergencies and maybe IFR circle to land. Rectangular traffic patterns not so much.

 

[dtuuri]

most pilots learning the maneuver have to resist the urge to use the rudder to just point the wing where they want it, since it supposed to be a coordinated manueuver.

I'll agree to that. Learning to "resist the urge" is the main advantage and never mentioned as the main goal. Circling while studying a small area on the ground without taking your eyes off of it is the accepted objective, but that doesn't transfer to any other application like resisting the urge to skid does.

 

[MauleSkinner]

Learning to "resist the urge" is the main advantage and never mentioned as the main goal.

It’s not mentioned as the main goal, but under “common errors” it has a whole paragraph on rudder coordination, followed by bullet points for “other” common errors, and one of the bullet points is slips and skids.

If “resisting the urge” isn’t being clearly taught, that’s handing at the instructor level.

 

[Roger Wilco]

I agree PA is an important concept for emergencies and maybe IFR circle to land. Rectangular traffic patterns not so much.

First, would you be willing to clarify the difference between "important concept" vs. the actual maneuver and pivotal altitude? Secondly, how, precisely, does mastery of the maneuver translate to emergencies and circling approaches?

 

[Roger Wilco]

With regard to the applicability of pivotal altitude and gunships, it seems highly unlikely that gunship pilots are direct (aim) fire by climbing and descending while turning around a target. Can anyone here describe the actual piloting technique used by gunship pilots? Does it involve calculating and maintaining pivotal altitudes while firing on a target?

 

[MauleSkinner]

With regard to the applicability of pivotal altitude and gunships, it seems highly unlikely that gunship pilots are direct (aim) fire by climbing and descending while turning around a target. Can anyone here describe the actual piloting technique used by gunship pilots? Does it involve calculating and maintaining pivotal altitudes while firing on a target?

Most likely it involves a lot of slipping and skidding.

 

[Roger Wilco]

Most likely it involves a lot of slipping and skidding.

So, no connection to pivotal altitude at all. I'd be interested in hearing from anyone who has actually flown gunships and has firsthand knowledge.

 

[RyanShort1]

Gunship techniques were closely related to the “bucket drop” system used by missionary Nate Saint. I am thinking the pivotal altitude would be unhelpful because you’re trying to maintain a constant radius or distance for the bucket line.

 

[Roger Wilco]

Gunship techniques were closely related to the “bucket drop” system...

Have you flown gunship missions?

 

[RyanShort1]

Have you flown gunship missions?

No, but the literature supports that theory.

https://arc.aiaa.org/doi/abs/10.2514/6.2002-5806

 

[455 Bravo Uniform]

So in my plane at my pattern speeds, if I’m turning final with no wind, if I’m below the pivotal altitude of 375 ft AGL then I would be at greater risk? If I have some headwind, then my pivotal altitude is even lower. So turning final above 500 AGL is advised? That’s probably not bad advice anyway.

We learn that stall-spins occur when pilots overshoot final and try to keep the turn going but using more rudder and less bank. Is that related to pivotal altitude and ground illusions?

 

[Roger Wilco]

No, but the literature supports that theory.

Interesting. I'd like to read the rest of the story, but not for 25 bucks. Thanks for posting the link.

Regardless, we can assume that flying a gunship is a specialized mission with its own specialized training. I don't think that it makes a case in support of the 8s-On-Pylons maneuver as part of a CPL syllabus.

 

[RussR]

ATP/CFII/MEI/IGI with about 2000 hours dual given, you’ll never convince me that 8’s on pylons and pivotal altitude is anything more than rubbish… I believe it’s one of the most useless things that’s required of the ACS. I could think of many more relevant items to take its place.

We all have opinions though.

Same ratings, instructional experience and opinion. I have also questioned (on this forum) about how in a slower airplane it's probably not even strictly legal due to the low altitude. But it seemed few others shared my view on that, oh well.

I don't really buy the "teaching this helps reduce base-to-final stall/spin accidents". Maybe it's just me, but I'm not typically looking at my wingtip when I'm turning final. I honestly have never noticed whether, on this turn to final, an object is falling behind my wingtip or moving ahead. Why would I? That doesn't makes any difference, and there are far more important things to be doing at the time.

 

[455 Bravo Uniform]

I went back and looked. Chapter 6 of the AFH is called Ground Reference Maneuvers.

The intro of Ch.6 is called Purpose and Scope. Reading it will give an idea of what these maneuvers are intended to convey to the learning pilot.

It has 8s on Pylons as the last maneuver. The intro paragraph of this section discusses its intended purpose.

Worth a read/review before we either criticize it, or give it more credit than it’s due.

 

[RussR]

I went back and looked. Chapter 6 of the AFH is called Ground Reference Maneuvers.

The intro of Ch.6 is called Purpose and Scope. Reading it will give an idea of what these maneuvers are intended to convey to the learning pilot.

It has 8s on Pylons as the last maneuver. The intro paragraph of this section discusses its intended purpose.

Worth a read/review before we either criticize it, or give it more credit than it’s due.

It's Chapter 7 in the current version (2021), and I don't see any headers for "Purpose and Scope". The introduction tells why ground reference manuevers are important, and I agree that most of the maneuvers and exercises have value that crosses into many other phases of flying. But not 8's on pylons.

The second sentence of the 8's on pylons chapter just says "Because of the techniques involved, the eights on pylons are unmatched for developing intuitive control of the airplane." Yeah, I can't agree with that. "Unmatched"? "Developing intuitive control"? Come on now.

 

[455 Bravo Uniform]

It's Chapter 7 in the current version (2021), and I don't see any headers for "Purpose and Scope". The introduction tells why ground reference manuevers are important, and I agree that most of the maneuvers and exercises have value that crosses into many other phases of flying. But not 8's on pylons.

The second sentence of the 8's on pylons chapter just says "Because of the techniques involved, the eights on pylons are unmatched for developing intuitive control of the airplane." Yeah, I can't agree with that. "Unmatched"? "Developing intuitive control"? Come on now.

Mine is the 2004 version. Maybe the more revisions, the more the editors are screwing around with the original understandings and purpose. When did the first AFH come out?

 

[brcase]

So in my plane at my pattern speeds, if I’m turning final with no wind, if I’m below the pivotal altitude of 375 ft AGL then I would be at greater risk? If I have some headwind, then my pivotal altitude is even lower.

Correct the lower your ground speed the lower the pivotal altitude, which provide for a normal looking turn. This part of the reason downwind turns are considered more dangerous because the pivotal altitude is higher make the urge skid the turn higher when you are below the pivotal altitude.

I have reviewed a lot of recorded flight traces from a number of different pilots and have found that very few normally turn final below 400feet.

Brian

 

[brcase]

I don't really buy the "teaching this helps reduce base-to-final stall/spin accidents".

Exactly just learning the maneuver does nothing to teach why we should think about pivot altitude. But at least it does give us the opportunity understand what pivotal altitude is. Without the 8's on pylons maneuver most pilots would have no idea what pivotal altitude is.

Maybe it's just me, but I'm not typically looking at my wingtip when I'm turning final. I honestly have never noticed whether, on this turn to final, an object is falling behind my wingtip or moving ahead. Why would I?

This is sort of the point of my post, the point is if you aren't noticing it and/or the ball, there is a very good chance you might be skidding the turn and not even realizing you are doing it, because it looks total normal. But the Ball (inclinometer) will say it is not.

Now if you have very good rudder skills, or have practice low level turns a lot then you may be doing it just fine. But would you do it just fine after an engine failure and having to perform a downwind turn to final? Knowing that there is a strong tendency to slow and skid turns when low and downwind may make you pay more attention to your coordination and airspeed.

Brian

 

[MauleSkinner]

Exactly just learning the maneuver does nothing to teach why we should think about pivot altitude. But at least it does give us the opportunity understand what pivotal altitude is. Without the 8's on pylons maneuver most pilots would have no idea what pivotal altitude is.




This is sort of the point of my post, the point is if you aren't noticing it and/or the ball, there is a very good chance you might be skidding the turn and not even realizing you are doing it, because it looks total normal. But the Ball (inclinometer) will say it is not.

Now if you have very good rudder skills, or have practice low level turns a lot then you may be doing it just fine. But would you do it just fine after an engine failure and having to perform a downwind turn to final? Knowing that there is a strong tendency to slow and skid turns when low and downwind may make you pay more attention to your coordination and airspeed.

Brian

If you’re not noticing a slip/skid condition without knowing about pivotal altitude, I can’t imagine how that would change if you knew about pivotal altitude.

 

[RussR]

Exactly just learning the maneuver does nothing to teach why we should think about pivot altitude. But at least it does give us the opportunity understand what pivotal altitude is. Without the 8's on pylons maneuver most pilots would have no idea what pivotal altitude is.




This is sort of the point of my post, the point is if you aren't noticing it and/or the ball, there is a very good chance you might be skidding the turn and not even realizing you are doing it, because it looks total normal. But the Ball (inclinometer) will say it is not.

Now if you have very good rudder skills, or have practice low level turns a lot then you may be doing it just fine. But would you do it just fine after an engine failure and having to perform a downwind turn to final? Knowing that there is a strong tendency to slow and skid turns when low and downwind may make you pay more attention to your coordination and airspeed.

Brian

I'm interested in why you think that watching the wing during a turn has any relation to being coordinated. That's what the ball, and your butt, are for. I also don't know why you infer that if I (and therefore my students) am not watching the wing, I (and they) therefore may not be watching the ball. I just don't see any relation between the two.

 

[Roger Wilco]

Correct the lower your ground speed the lower the pivotal altitude, which provide for a normal looking turn.

What do you mean by "normal looking turn?"

This part of the reason downwind turns are considered more dangerous...

Who considers downwind turns to be more dangerous? Decades ago there were misinformed pilots who believed that the wing would stall when turning downwind at a slow airspeed, but I don't recall anyone ever claiming that pivotal altitude was in any way a factor that increased the danger.

Exactly just learning the maneuver does nothing to teach why we should think about pivot altitude. But at least it does give us the opportunity understand what pivotal altitude is. Without the 8's on pylons maneuver most pilots would have no idea what pivotal altitude is.

If I had never learned what pivotal altitude is, it would have made no difference whatsoever. The ONLY reason to calculate pivotal altitude is to teach pylon 8s or pass a checkride.

This is sort of the point of my post, the point is if you aren't noticing it and/or the ball, there is a very good chance you might be skidding the turn and not even realizing you are doing it, because it looks total normal. But the Ball (inclinometer) will say it is not.

A good reason to forget about the wingtip and remember to crosscheck the inclinometer instead.

...Knowing that there is a strong tendency to slow and skid turns when low and downwind may make you pay more attention to your coordination and airspeed.

Maintaining proper airspeed and control coordination are fundamental skills that have nothing to do with pivotal altitude, nor is an understanding of pivotal altitude in any way applicable to learning and applying those skills. 8s-on-pylons merely provide a more challenging maneuver to practice and demonstrate proficiency in controlling the aircraft in all three axes simultaneously while dividing our attention between inside and outside references, and calculating a pivotal altitude is necessary to make the maneuver work as intended.

39 posts in, and nothing has been added to this thread that supports your assertion that pivotal altitude contributes in any meaningful way to spin avoidance.