Bubbler

That's really your preference on how long you want to wait. If the eights on pylon presentation is the only big issue the original guy had with your oral, then I'd go with the other DPE in a week.

But don't worry about the other exam being observed, if you go with that one. The observation is for the examiner, not you. They'll be making sure the DPE is administering a proper examination, just like the examiner is making sure you're teaching correctly.

The DPE I flew with for my CFI said that when he's observed, they often get on him about teaching too much during examinations. If they're doing good, he likes to give tidbits of advice. FSDO doesn't like that, but me and everyone else I know who flew with him did.

lstorm2003

So what ever happened with this? Did you eventually get it done?

And can I ask a dumb question.. When you found out this examiner wanted you to calculate pivitol based on TAS why didnt you just make it easy on yourself and do that? He is the one who can pass you or fail you. The book cannot give you your ticket, so why not just do it his way and move on?

Sounds to me like he got annoyed that he told you that HE wanted you to use AS not GS and you used GS anyway.

Not saying he's right I'm just saying the goal should be gettting your ticket. Not proving the examiner wrong. Unless its a safety issue who cares?

JamesNoBrakes

Because that is against pretty much everything a pilot should be about and the other people that will fail because this DPE is requiring applicants to teach in conflict with the approved material? Are you going to have that attitude when the captain does something against regulations or when the company asks you, just to "get it done"?? Seriously?

TonyC

Equating this Inspector's affinity for TAS or GS to a Captain asking you to violate a regulation is quite the stretch. It seems to me that doing it the way the Inspector likes is a wise strategy, and once the pilot has a signed certificate in hand, he can always ask the Inspector to explain something he doesn't quite understand.


I read this thread when it started, but I didn't read the old threads until today, and I just now reviewed the applicable section of the Airplane Flying Handbook. If you're skimming for the answer you want to find, Figure 6-12 and the sentence that precedes it actually confuses the matter. Here are some pertinent excerpts:

(Start on Page 6-12, or page 89 of the Adobe document)

In the text, there are numerous references to groundspeed:Figure 6-10 refers to groundspeed:andLater in the text ...


bank is steep enough to affect the groundspeed."

Here's where it might be confusing:What immediately follows is Figure 6-12 "Speed vs. pivotal altitude", which lists "Airspeed" and "Approximate Pivotal Altitude"


But, go back and read that last sentence more carefully. There is an important caveat that is being missed.In calm wind, the true airspeed and the groundspeed will be the same, so there is no contradiction with the text that precedes or follows this table and the sentence than introduces it.

This sentence and table DO NOT CONSTITUTE FAA INSTRUCTIONS to use TAS to determine Pivotal Altitude! Using airspeed only works in calm wind! The text is replete with explanations that pivotal altitude is a function of groundspeed and groundspeed alone. Changes in groundspeed require changes in pivotal altitude, and therefore require climbs and descents.

Again, later in the text,Later ...(6-03-2008)
Airplane Flying Handbook and both of the fine references you included very emphatically aver that pivotal altitude (or pivotal height) in other than still air is a function of groundspeed, and groundspeed alone.


(6-04-2008)
The table you reference in Airplane Flying Handbook is for calm winds only. In anything other than calm winds, pivotal altitude is a function of groundspeed, not airspeed. Read the sentence prior to the table very carefully ... "... in calm wind ..." is an important clause.


(6-04-2008)

Um, no. The physics are the physics, and the references you linked explain and support the physics.

(6-04-2008)
The FAA does NOT say use airspeed. It says if the winds are calm, here's a table that will work with airspeed. The entire text explains how and why the pivotal altitude changes with groundspeed, which is why you have to push or pull to make the airplane go up or down to keep the pylon on the sightline without changing the bank angle.



(7-28-2009)

YES! You got it correct!







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Mistek89

I passed with a different examiner, I am already instructing at a flight school

Cubdriver

Tony, you're picking nits and I have long since stopped thinking about this topic very deeply anyway. This thread is 5 years old. But I still hold that the best practical method to use for this maneuver is to target an airspeed, not a groundspeed. Yes the physics is the physics I am not talking about that. I am talking about how to teach this maneuver. Why airspeed? Because that's what the pilot sees, not groundspeed. No aircraft has a groundspeed dial in the 6 pack. I teach a student looking at wing tip and 6-pack instruments to go back and forth between these things, and not waste time second guessing what some off axis gps unit, assuming they even have one, shows for GS and it will be changing a lot anyway. The idea is to target an appropriate indicated airspeed, maintain it, and adjust your altitude by dipping and climbing as necessary to keep the wingtip where it is supposed to be. It's an eye hand exercise, not a physics lesson. But if you do not agree then fine, we can agree to disagree on this one. I have FAA dogma behind me plus my practical experience teaching it which is good enough for me. Use zero wind groundspeed and an altitude guesstimate to come up with a target pivotal altitude while still on the ground planning the flight, then fly the manuever using airspeed and be happy.

TonyC

Naw, picking nits would be showing how the 60-to-1 rule is an approximation, not an exact, mathematically accurate formula.

But, since you think I'm picking nits, let me point out THIS thread is only two months (plus some days) old, and one of the threads you referenced is over SIX years old.

But the correct answers never change.

And here's the thing. Mistek89, the guy that started THIS thread, explained EXACTLY CORRECTLY how to do Eights-on-pylons, and the threads you offered as reference have you telling him (us) a different (incorrect) way. I just thought it would be fair to use the webpages you linked, showing the physics of the maneuver and the mathematical derivation of 11.3 in the formula, to drive home the point that Mistek89 had it correct all along. To quote, "The derivation is interesting not only because it explains why we use the value 11.3, but also because it demonstrates why the pivot height does not depend on any factors other than groundspeed." I also cited the FAA source document that supports his explanation.


The pilot flies an airspeed, true. And yet every ground reference maneuver he flies takes into account the fact that there is WIND. To quote the Airplane Flying Handbook, "Ground track or ground reference maneuvers are performed at a relatively low altitude while applying wind drift correction as needed to follow a predetermined track or path over the ground. They are designed to develop the ability to control the airplane, and to recognize and correct for the effect of wind ..." The Rectangular Course, S-turns across a road, Turns about a point, Eights along a road, Eights across a road, and Eights around pylons all require adjustments for ... wind. So, too, do eights on pylons.

Planning a maneuver and flying a maneuver are both critical skills, and the substance of the debate here is not how to fly it, but how to plan it.

For eights on pylons, the key is to begin at the correct altitude, and that altitude is determined by groundspeed. Mistek89 did that, accounted for wind, while his feet were still firmly planted on the ground. He said, we have a wind today, and based on that wind and the airspeed we plan to fly, the groundspeed when we tip the wing to begin our first orbit on the pylon will be X knots, and based on that groundspeed, our pivotal altitude will be X squared divided by 11.3. Add that to the height of the terrain where we'll be performing this 8 on pylons, and we've got an entry airspeed and altitude to read off the six-pack.

Proper Planning Prevents **** Poor Performance


That sounds like a great way to think about it when you get there and are flying the maneuver. If you have also planned it correctly, using groundspeed to determine your beginning altitude, it should be a textbook eights on pylons. However, if you begin at the wrong altitude because you didn't bother to adjust your groundspeed for wind, you're going to have a harder time making it look right, and the stronger the wind the harder it will be. But why would you want to begin from a deficit? Use Mistek89's preflight planning and it should turn out slick as a whistle!


Ouu, here's the part that I've been waiting to get to.

Please describe this FAA dogma. Do you have a reference?

I've got the Airplane Flying Handbook on my side. Do you have a trump card?


Sure, I've flown with plenty of guys that use the "T-LAR" method. And they were pretty happy. So is my dog.






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TonyC

CONGRATULATIONS!

Glad you got that one over with!






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Cubdriver

Tony, you're wrong again, plus your mother dresses you funny.

This maneuver is started from a more or less parallel and crosswind orientation to the pylon axis, see the Airplane Flying Handbook page 6-12, not on the downwind. In theory this maneuver is begun on a crosswind because starting the maneuver without winds pushing/ pulling the airplane helps the pilot get established as easy and fast as possible before things get challenging with the prevailing winds. And this means the no-wind groundspeed is the relevant number to use in the pivotal altitude formula in the classroom before grabbing that last donut and taking a leak before heading out. And it's more relevant than some guesstimate of wind speeds using TAFs, Area Forecasts, Winds Aloft, Pireps, onboard gps, pond streaks, smoke plumes or any other method. Forget it!