dtuuri
Final Approach
I supported the assertion.
If you skid around a pylon, you could bust. If you skid around a turn to final, you could die.
Pivotal altitude. Why it matters...
- Thread starter brcase
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If you skid around a pylon, you could bust. If you skid around a turn to final, you could die.
Pivotal altitude has nothing to do with skidding a turn, except when performing pylon 8s.I supported the assertion.
dtuuri
Final Approach
Says you.
Says physics. But if you can explain just how it is that pivotal altitude contributes in any meaningful way to spin avoidance I'm definitely interested.
Clip4
Touchdown! Greaser!
w
Concept - a principle or idea.
VS
Maneuver - movement or series of moves requiring skill and care.
Pivotal Altitude - altitude at which, for a given groundspeed, the projection of an imaginary visual reference line to a single point on the ground appears to pivot
Precisely - in exact terms; without vagueness.
if you understand the importance of an emergency or circle to land maneuver, understand concept of pivotal altitude by practicing the 8s on maneuver, you will be able to perform circle to land and emergencies more precisely.
Hope that helps.
Important - of great significance or value; likely to have a profound effect on success, survival, or well-being.
Concept - a principle or idea.
VS
Maneuver - movement or series of moves requiring skill and care.
Pivotal Altitude - altitude at which, for a given groundspeed, the projection of an imaginary visual reference line to a single point on the ground appears to pivot
Precisely - in exact terms; without vagueness.
if you understand the importance of an emergency or circle to land maneuver, understand concept of pivotal altitude by practicing the 8s on maneuver, you will be able to perform circle to land and emergencies more precisely.
Hope that helps.
dtuuri
Final Approach
I have a good memory of how hard it was to keep from skidding the wing into position back when I worked on my commercial license. It took enormous restraint and self-discipline, an awareness I often forced myself to invoke in subsequent years when making turns low to the ground under the effect of a strong wind. The temptation to inappropriately use rudder is stronger during on-pylons than any other maneuver I can recall. I think the OP and author he cited are making that point too, so that's at least three of us.
MauleSkinner
Touchdown! Greaser!
If you understand the importance of an emergency or circle to land maneuver, understand the concept of a stabilized approach by practicing them, you will be able to perform circle to land and emergencies more precisely.
personally, I’ll pick the one that most pilots are likely to continue practicing after the commercial checkride.
You had previously posted, "I agree PA is an important concept for emergencies and maybe IFR circle to land. Rectangular traffic patterns not so much." In this sentence, you characterized PA (I assume you meant pivotal altitude) as an important concept. I merely wanted clarification of your intent with regard to emergencies and circling approaches. Your reply didn't answer my question, but thank you for providing definitions of terms that were not a matter of contention. Seems like lot of extra trouble merely for the appearance of being argumentative.
Okay, I'll bite: In what type of emergency maneuver does pivotal altitude come into play? As for circling approaches...pure nonsense; or can you tell me how you would fly a circle-to-land approach by calculating and maintaining pivotal altitude while maneuvering to land?
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Maybe the issue here is a matter of differentiating between the maneuver, 8s-on-pylons, and a component of the maneuver, pivotal altitude. I contend that they are two different things. As I stated in post #40, 8s-on-pylons are one way to practice "controlling the aircraft in all three axes simultaneously while dividing our attention between inside and outside references..." which could indeed be helpful in learning the proper use of controls including the rudder. I went on to say "calculating a pivotal altitude is necessary to make the maneuver work as intended." If we seek to perfect our use of flight controls, then pylon 8s (my preferred term) are a good way to hone those skills. But pivotal altitude is not applicable to anything other than the proper execution of this maneuver. So if you wish to argue that the pylon-8 maneuver was helpful in learning to avoid improper use of the rudder, that makes perfect sense. If you were to continue to assert that proper use of rudder reduces the chance of a low-altitude stall/spin, then I'm in complete agreement. If you then connect the maneuver, pylon 8s, to a reduced chance of auguring-in, I think that's a valid cause/effect relationship. My point is that pivotal altitude itself has nothing to do with avoiding stall/spin accidents and has no meaningful application in the real world.
Clip4
Touchdown! Greaser!
So you believe the only way one can recognize they are at PA is math? On an emergency approach to landing or a circle to land, the pilot recognizing PA can hold a point and descend without increasing bank / G loading as the ground speed changes with the effect of the wind,
MauleSkinner
Touchdown! Greaser!
So which emergency has you holding a point on your wingtip and climbing and descending to keep it there? And why is climbing and descending to maintain a point on your wingtip a valid technique for circling to land?
RyanShort1
Final Approach
I generally respect the IP and appreciate many of his posts, but reading the OP, my professional opinion is that this is a "gotcha" question of minimal value on a flight review and if it was my flight review I would say "ok" and can we please move on?
Usually I'm the one who is unclear on the concept. This time, however...
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dtuuri
Final Approach
Depends. One time I wanted to study the area around my house as I returned from a trip, deadhead. I had my copilot figure the pivotal altitude, around 3000' MSL, IIRC, so I could circle without looking inside at all. I thus avoided a stall/spin.
Ryan F.
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Ryan Ferguson 1974
Just my personal opinion: the correlative connection between, specifically, pivotal altitude and stall-spin awareness as presented is interesting, but a tad tenuous. That said, it sparked discussion and that is always good. To the point, any enhancement in aeronautical knowledge, and the application of that knowledge (pivotal altitude) when demonstrating smoothness and precision in aircraft control can only be of benefit to safety.
Eights-on-pylons are a ground reference manuever, and per the Airplane Flying Handbook, "... ground reference maneuvers train the pilot to accurately place the airplane in relationship to specific references and maintain a desired ground track." The AFH goes on to describe Eights-on-pylons as "the most advanced and difficult" of the ground reference manuevers and state they are "unmatched for developing intuitive control of the airplane." That sounds about right to me.
The key phrase from the AFH is on p. 7-15: "This develops the pilot’s ability to maneuver the airplane accurately while dividing attention between the flightpath and the selected pylons on the ground." That is the critical skill which is honed from properly learning this maneuver.
In short, a well-flown Eights-on-Pylon task requires division of attention, and an intuitive sense of the aircraft's coordination. These skills are certainly called upon in the traffic pattern as well, such as scanning for traffic while maintaining awareness of AOA/airspeed, aircraft configuration, coordination, etc. especially while turning.
So is there a connection between properly taught, satisfactorily demonstrated Eights-On-Pylons and pilot skills which could help prevent a low altitude stall-spin? Absolutely. Carry on!
Eights-on-pylons are a ground reference manuever, and per the Airplane Flying Handbook, "... ground reference maneuvers train the pilot to accurately place the airplane in relationship to specific references and maintain a desired ground track." The AFH goes on to describe Eights-on-pylons as "the most advanced and difficult" of the ground reference manuevers and state they are "unmatched for developing intuitive control of the airplane." That sounds about right to me.
The key phrase from the AFH is on p. 7-15: "This develops the pilot’s ability to maneuver the airplane accurately while dividing attention between the flightpath and the selected pylons on the ground." That is the critical skill which is honed from properly learning this maneuver.
In short, a well-flown Eights-on-Pylon task requires division of attention, and an intuitive sense of the aircraft's coordination. These skills are certainly called upon in the traffic pattern as well, such as scanning for traffic while maintaining awareness of AOA/airspeed, aircraft configuration, coordination, etc. especially while turning.
So is there a connection between properly taught, satisfactorily demonstrated Eights-On-Pylons and pilot skills which could help prevent a low altitude stall-spin? Absolutely. Carry on!
RussR
En-Route
I respect your opinion as an experienced DPE, Ryan, but I'm still not convinced that the 8's on pylons are anything but a made-up exercise in order to have something new to do and learn for the Commercial.
Note that if you're doing your Commercial in a multi (even if it's your initial Commercial), you will not learn or have to perform them on the checkride. If, as the FAA states, they are so great that they are "unmatched for developing intuitive control of the airplane", wouldn't we want our multiengine pilots to benefit from this maneuver as well? After all, speeds would be higher and therefore pivotal altitude would be higher, so it would be "safer".
But I don't see them as some awesome training exercise. They're really quite simple.
Pre-calculate a few pivotal altitudes for various groundspeeds you are likely to have and put them on a sticky note on the panel.
Start at the altitude appropriate for your current ground speed.
If the pylon moves forward, you're too high - push.
If the pylon moves back, you're too low - pull.
Roll out 270 degrees after entry (I recommend setting the heading bug prior to entry) and do the other pylon.
Students realize pretty quickly that all they have to do is push or pull in the same direction that the pylon is moving. Sure, they can get all wrapped up in the pivotal altitude concept and derivation thereof (like the ERAU video on the math of the PA, which personally I find very interesting, but most don't and it's completely unnecessary anyway), but really it just comes down to "push or pull".
Sure, I've had it where they lose situational awareness and forget when to roll-out and head toward the next pylon, but heck that happens with turns about a point and other maneuvers like steep turns as well.
The whole other discussion here about circling approaches and emergency landing maneuvering makes no sense to me either, I can't see any connection between those and PA or 8's on pylons at all.
Correlation is not causation. It wouldn't have mattered how you flew the maneuver, so long as you didn't stall you would have avoided a stall/spin.
Sounds similar to what had been said in a previous post: "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."
But the usefulness of the maneuver 8s-on-pylons is not at issue. The title of the thread, and subject of the first post, is pivotal altitude, not 8s-on-pylons. The connection drawn by the OP between pivotal altitude and stall/spin accidents is, as you put it, tenuous. Actually, tenuous is generous.
Over and out.
Ryan F.
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Russ,
I don't have any interest (or ability) to get into the history of the task, or why/how it was developed. I can only say that from my little corner of the airman certification world, the task has its place and it holds plenty enough value to warrant its inclusion in the ACS. Though it may seem simple to you as an accomplished instructor, I've watched more than a few applicants struggle with the task. Of course, I've seen others demonstrate a high level of skill. In my experience the applicants that struggle tend to already have a difficult time dividing attention or multi-tasking in general. For example, working a navlog, computing a T/S/D while hand flying, that sort of thing. Skills a commercial pilot needs to have.
This may be the sort of observation that's borne of the unique perspective of watching many individuals demonstrate the task as part of a checking event, rather than being part of the instructional path. I haven't taught commercial maneuvers in years.
The ACS treats the Eights-on-Pylons with extra care. Per Appendix 7: Aircraft, Equipment, and Operational Requirements & Limitations:
Not that it's the subject of discussion anyway, since this task isn't going anywhere, but I think it serves a useful role in a pilot's development. Perhaps one could argue there's a better manuever for that job... in the fertile imagination of an active flight instructor, somewhere, ready to submit the idea to the FAA and its industry stakeholders. In the meantime, Eights on Pylons will have to do.
Thanks for a great discussion!
I don't have any interest (or ability) to get into the history of the task, or why/how it was developed. I can only say that from my little corner of the airman certification world, the task has its place and it holds plenty enough value to warrant its inclusion in the ACS. Though it may seem simple to you as an accomplished instructor, I've watched more than a few applicants struggle with the task. Of course, I've seen others demonstrate a high level of skill. In my experience the applicants that struggle tend to already have a difficult time dividing attention or multi-tasking in general. For example, working a navlog, computing a T/S/D while hand flying, that sort of thing. Skills a commercial pilot needs to have.
This may be the sort of observation that's borne of the unique perspective of watching many individuals demonstrate the task as part of a checking event, rather than being part of the instructional path. I haven't taught commercial maneuvers in years.
The ACS treats the Eights-on-Pylons with extra care. Per Appendix 7: Aircraft, Equipment, and Operational Requirements & Limitations:
For initial commercial applicants seeking an ASEL or ASES rating, the evaluator must choose:
• Task A, Steep Turns, or Task B, Steep Spiral;
• Task C, Chandelles, or Task D, Lazy Eights; and
• Task E, Eights on Pylons.
Of all the maneuvers contained within AOA V., Task E is the one the applicant must demonstrate regardless of evaluator preference.Not that it's the subject of discussion anyway, since this task isn't going anywhere, but I think it serves a useful role in a pilot's development. Perhaps one could argue there's a better manuever for that job... in the fertile imagination of an active flight instructor, somewhere, ready to submit the idea to the FAA and its industry stakeholders.
In the meantime, Eights on Pylons will have to do.Thanks for a great discussion!
Roger, Wilco, Over and Out.
Could not agree with Roger Wilco more. Commercial check ride half a century ago. Never used the skill, but keep the ball centered for all turns. Proper scan, and multitasking is the skill to be established, and can be verified at a safe altitude. I was better at pilon 8's than some of my instructors.
Could not agree with Roger Wilco more. Commercial check ride half a century ago. Never used the skill, but keep the ball centered for all turns. Proper scan, and multitasking is the skill to be established, and can be verified at a safe altitude. I was better at pilon 8's than some of my instructors.
RussR
En-Route
Appreciate the viewpoint as always.Russ,
I don't have any interest (or ability) to get into the history of the task, or why/how it was developed. I can only say that from my little corner of the airman certification world, the task has its place and it holds plenty enough value to warrant its inclusion in the ACS. Though it may seem simple to you as an accomplished instructor, I've watched more than a few applicants struggle with the task. Of course, I've seen others demonstrate a high level of skill. In my experience the applicants that struggle tend to already have a difficult time dividing attention or multi-tasking in general. For example, working a navlog, computing a T/S/D while hand flying, that sort of thing. Skills a commercial pilot needs to have.
This may be the sort of observation that's borne of the unique perspective of watching many individuals demonstrate the task as part of a checking event, rather than being part of the instructional path. I haven't taught commercial maneuvers in years.
The ACS treats the Eights-on-Pylons with extra care. Per Appendix 7: Aircraft, Equipment, and Operational Requirements & Limitations:
For initial commercial applicants seeking an ASEL or ASES rating, the evaluator must choose:• Task A, Steep Turns, or Task B, Steep Spiral;• Task C, Chandelles, or Task D, Lazy Eights; and• Task E, Eights on Pylons.Of all the maneuvers contained within AOA V., Task E is the one the applicant must demonstrate regardless of evaluator preference.
Not that it's the subject of discussion anyway, since this task isn't going anywhere, but I think it serves a useful role in a pilot's development. Perhaps one could argue there's a better manuever for that job... in the fertile imagination of an active flight instructor, somewhere, ready to submit the idea to the FAA and its industry stakeholders.
Thanks for a great discussion!
I don't think that my instructional techniques for this are amazing or novel. I certainly didn't make them up. So I'd say that if you as the examiner are seeing problems with this maneuver, it's due to poor instruction from CFI's who don't know how to teach it, not due to the difficulty of the maneuver. (Of course, poor instruction is ultimately the result of most of the problems you see, I'm sure.)
You can fly this maneuver pretty much just through rote application of starting altitude, when to push and pull, and entry/exit headings. It does not require the finesse and constant changes in control forces and coordination that is required of Chandelles or Lazy 8's. It doesn't require the attention to altitude and bank angle and proper amount of back pressure of steep turns. It doesn't require making ground track adjustments and bank angles for varying wind like turns about a point or S-turns across a road.
dtuuri
Final Approach
I don't think it's simply push and pull. To really learn something, you need to just do on-pylons, no 8s. Hang in there around and around a few times and see how it goes. Chances are, you'll wind up losing the pylon all together if you aren't good at it. Rolling out for an "eight" is like cheating.
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brcase
En-Route
I am not saying you should be watching the wing, In fact exactly the opposite. What I am saying is that as pilots we are used to seeing things looking a certain way... The ground going by at a certain Speed, A specific pitch attitude out the window, and the inboard wing moving backwards in a turn. I am saying we can or may be underestimating how much we depend on these visual cues and need to be cautious and understand when our visual cues may deceive us. For example we talk a fair amount about wide vs narrow and sloped runways how they change the visual ques for us, even though this probably doesn't have a lot of relevance toward stall spins, other than it could lead you to come in lower than normal, causing other visual illusion.
We also teach believe the instruments when instrument flying and most of us have experienced how hard this can be when we are feeling something different that what the instruments tell us. Think about how we react when what we are seeing is different that what the instruments tell us, Like a skidded turn below pivotal altitude looks normal or a normal coordinated turn below pivotal altitude looks like a slipping turn.
My 1st experience with visual illusions was on off airport landing in my glider where my final was over a hill so my AGL altitude was only 1 to 200 feet. The Approached looked and felt normal, but the glider started giving me indications of stall (oil canning of the aluminum wing skins). Glider we do lots of slow flight when climbing so I was intimately familiar with this indication and immediately put then nose down observing the ASI was at Stall speed I sped up to normal approach speed, then started scanning my landing area noting some power lines to make sure I would miss and moments later I was gain at Stall speed. What I observed is this feeling was exactly like the leans when on instruments, where if you look away from the instrument for more than a few seconds you will start to do what you are feeling, Just in this case what I was feeling was caused by what I was seeing, ie. the ground closer than normal and appearing to be going faster than I really was.
I have since watched many Stall Spin Accident Video and accident reports and have noted these kinds of illusions are if not obviously present, easily could have been.
Another event like this was a Champ I used to teach in, the pilot did downwind uphill approach to the airstrip on the go around he stalled and spun it in, fortunately from only about 20 feet, and he walked away from it, but totaled the airplane, Not pivotal altitude but defiantly the appearance of high ground speed close to the ground..
Another local accident that easily could have been related to the Pivotal altitude illusion...
The whole point of understanding these illusions is to realize unless you are looking for them or doing something to prevent them you may be the pilot that would "never do that" without even realizing you are doing exactly that. The more you understand where these illusions can occur you can be more vigilant about preventing them from turning into an accident.
Brian
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Hang 4
Brian, I think your last post was where you were going all along and the pivotal altitude confused rather than clarified. I'll give an example of what I think you are trying to get across. In a hang glider, "pattern speed" is roughly 25 - 30 MPH. Pretty darn slow. If you are flying a standard pattern in a 15 mph wind, your downwind leg is going to be scary fast relative to the ground. Our patterns are much lower than GA, typically ~ 500 AGL on downwind. You have to will yourself to fly airspeed vs groundspeed and the downwind turn can easily produce a stall if you aren't paying attention to airspeed.
In GA that effect is much less pronounced due to the higher absolute speeds in the pattern relative to normal wind speeds. The effect can still manifest itself in the turn from downwind to base if you see the ground moving faster than you expect and you kick in extra rudder to compensate. Since you fly gliders, with their long skinny wings, the effect of the tip moving relative to the ground might be a bit more pronounced. Hence the pivotal altitude starting point?
In GA that effect is much less pronounced due to the higher absolute speeds in the pattern relative to normal wind speeds. The effect can still manifest itself in the turn from downwind to base if you see the ground moving faster than you expect and you kick in extra rudder to compensate. Since you fly gliders, with their long skinny wings, the effect of the tip moving relative to the ground might be a bit more pronounced. Hence the pivotal altitude starting point?
RyanShort1
Final Approach
Hang 4 is on to something. I’d be completely OK with a discussion about visual illusions on a flight review.
Tarheelpilot
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Tarheelpilot
I have thousands of hours operating at low altitudes working as an ag pilot. The end of every pass was a low level ground reference maneuver. I never noticed diddly squat about the relative motion of objects on the ground in reference to my wing tip. This claim of importance feels like a solution looking for a problem.
dtuuri
Final Approach
Lazy eights aren't under discussion, just sayin'...
Tarheelpilot
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Tarheelpilot
I edited my post to remove the lazy eight. I mistyped. Thanks for pointing it out so I could edit for clarity but it doesn’t change my position.
bbchien
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Search and rescue at sea.....