Slow flight to PTS standards is impossible

[dmspilot]

Contradiction in FAA Slow Flight PTS standards

TASK: MANEUVERING DURING SLOW FLIGHT

Objective. To determine that the applicant:

1. Exhibits knowledge of the elements related to maneuvering during slow flight.
2. Selects an entry altitude that will allow the task to be completed no lower than 1,500 feet (460 meters) AGL.
3. Establishes and maintains an airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in an immediate stall.
4. Accomplishes coordinated straight-and-level flight, turns, climbs, and descents with landing gear and flap configurations specified by the examiner.
5. Divides attention between airplane control and orientation.
6. Maintains the specified altitude, ±50 feet (15 meters); specified heading, ±10°; airspeed +5/−0 knots, and specified angle of bank, ±5°.

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

Starting with just straight and level slow flight, it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall, and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

 

[gtcfi]

Add power in the turn. The increased vertical component of thrust makes up for the reduced vertical component of lift.

In less technical terms, in slow flight, altitude is controlled with power. If you are descending in level flight, add power. Likewise, in the turn, avoid descending by adding power.

 

[nosehair]

it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall,

Ah, it is humanly impossible, that's why only pilots can do it. :wink2:

and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

That's actually pretty easy. When the applicant says he/she has it in slow flight, I reach up and pull slightly on the yoke. If I get a stall buffet, he/she is in "PTS Slow Flight". If the nose pitches up a bit and no immediate buffet or stall, he/she is not there yet.

Really, you can do it. One of the purposes/reasons for teaching this knife-edge slow flight is for the student pilot to really "feel" the edge of the stall. A pilot should really know when the stall will occur. He/She should have the feel of the elevator just on the ragged edge of the buffet before stall, and keep it there by elevator feel.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

Add some power. This actually decreases angle of attack.

 

[gismo]

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

Starting with just straight and level slow flight, it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall, and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

The word "infinitesimal" isn't in the PTS and "any further increase" really means a perceptible increase (e.g. a few degrees). I wouldn't get in a sweat over this if I were you.

 

[RyanShort1]

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

Starting with just straight and level slow flight, it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall, and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

They do give you a 5 KT window...
Slow flight is one of my favorite maneuvers, because a lot of folks are really afraid to take the plane and explore it's envelope, and fly it WELL throughout the envelope. It's quite satisfying to add a touch of power and hold the Cub at 33 mph indicated in slow flight while turning, maintaining altitude, and moving backwards. I've found that a lot of folks are simply afraid of the edge, not smooth enough in their control inputs, and careful enough with their banking and coordination to do slow flight well.

Ryan

 

[tonycondon]

well you obviously have to reduce the AoA when you enter the turn in order to maintain an attitude that allows for the PTS description of the manuever. And then, in order to maintain altitude, you have to add power.

 

[dmspilot]

Thanks nosehair and gtcfi and tony...I am just doing the ground work now, so this is all hypothetical, but will try out your techniques next time I do slow flight.

The word "infinitesimal" isn't in the PTS and "any further increase" really means a perceptible increase (e.g. a few degrees). I wouldn't get in a sweat over this if I were you.

The word "any", to me, means just that: any. Including infinitesimal. So it should say "perceptible increase" not "any increase". Not that I'm getting in a sweat...I just disagree with the FAA and think it's an example of government incompetence.

They do give you a 5 KT window...

You are right, it says -0/+10 knots actually. Which IMO contradicts the other standard that comes right before it. So I still say the FAA is being boneheaded with their wording. How can you be required to be right on the edge of the stall yet have a tolerance of -0/+10 knots...it's beyond logic to me.

 

[denverpilot]

I like slow flight, but with the R/STOL it's really slow in our bird and abusive on the engine, temperature-wise in the summer. The stall fences "sing" for lack of a better word. Once the buffet starts you're still flying straight ahead and dropping like a rock, totally under control.

I was demonstrating this for a pilot buddy this summer, but power off. Let the speed bleed off and kept coming until the elevator was full-up and I wrapped my forearms around the yoke from underneath and held it there to save on forearm fatigue.

Nose bobs up and down, VSI is pegged down, rumbles the wing from airflow separation and the stall horn is of course, screaming the whole time. Just kinda watch the world bob up and down until you're bored with it or scrubbed too much altitude. Ponderous slow turns are easy with limited bank angles and a bit of rudder.

At least one instructor *thought* we were established in slow flight once when I said, "Oh she'll fly slower and still maintain altitude. Hang on, we're not there yet."

Stable is an understatement. It's just a hoot.

 

[dmccormack]

How can you be required to be right on the edge of the stall yet have a tolerance of -0/+10 knots...it's beyond logic to me.

An excellent lesson in reading ONLY THE REQUIREMENT and not ADDING to the requirement.

Learn this well if you want to progress through the FAA's knowledge and practical tests with minimal fuss.

 

[RyanShort1]

You are right, it says -0/+10 knots actually. Which IMO contradicts the other standard that comes right before it. So I still say the FAA is being boneheaded with their wording. How can you be required to be right on the edge of the stall yet have a tolerance of -0/+10 knots...it's beyond logic to me.

Because they're not actually "boneheaded" - and recognize that on for instance a bumpy, thermally day, you may need a tiny bit of margin to deal with wind shear, etc... the idea is for you to TRY and get the aircraft to that point where an angle of attack cannot increase without stalling.
Again, this is about your ability to coordinate the aircraft, feel it, and manage your bank angles. Remember that your Load Factor with a bank rises very slowly until you get past a certain point, and when you are doing shallow banks, your stalling speed does not increase significantly. Also, this maneuver is frequently done with the trainee's head buried in the cockpit, which is not the right way to do it. You should bring your speed back and verify it on the airspeed indicator, but should then be 90% visual, which means you have to feel the aircraft, and see how it is responding. A quick look at the Airplane Flying Handbook and the section on "common errors" on slow flight would be a good start.

Ryan

 

[poadeleted20]

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

How much experience does the instructor training you have?

 

[gismo]

The word "any", to me, means just that: any. Including infinitesimal. So it should say "perceptible increase" not "any increase". Not that I'm getting in a sweat...I just disagree with the FAA and think it's an example of government incompetence.

Well you can disagree with the FAA all you want but as CFI you're not going to get very far if you do that nor will this be the last bit of "incompetence"/inconsistency you'll find.

 

[dmspilot]

How much experience does the instructor training you have?

What difference does it make? I said I am only studying for the ground portion at this point.

Just to make it perfectly clear. My issue is with the wording of the PTS, not the performance of the maneuver.

 

[dmspilot]

An excellent lesson in reading ONLY THE REQUIREMENT and not ADDING to the requirement.

Learn this well if you want to progress through the FAA's knowledge and practical tests with minimal fuss.

Say again? The PTS wants you to be on the edge of a stall, yet gives you a tolerance of 10 knots. What have I added to the requirement?

Remember that your Load Factor with a bank rises very slowly

But it rises nonetheless. Anyway, your point about "trying" to get it there but giving you a tolerance for gusts and such is noted. This seems to be the FAA's intent. I can accept your interpretation of the PTS...though I prefered it the way it was before...

 

[poadeleted20]

What difference does it make? I said I am only studying for the ground portion at this point.

Sorry, I assumed your position was based on actually having gone through the training on how to teach the maneuver, not just a critical reading of the PTS.

Just to make it perfectly clear. My issue is with the wording of the PTS, not the performance of the maneuver.

Well, you're free to quibble, but the FAA has been honing that definition for a very long time, and they're pretty well satisfied that when combined with the general guidance at the beginning of the PTS, it provides an adequate description for what they want taught and how they want it performed, and pretty much everyone who has completed CFI-A training understands it. Of course, if you think you have a better way to word it, AFS-600/800 will probably be happy to consider your better way and your justification for changing it.

 

[dmspilot]

the FAA has been honing that definition for a very long time

Not true. The part I'm having issue with was written that way in 2002 and it hasn't been changed at all since then. Before that, it was completely different:

3. Stabilizes and maintains the airspeed at 1.2 VS1, ±5 knots.

Now, I suppose 20% above stall was a bit too generous, but now they imply that they want 0.00000001% above stall...I think they've gone overboard here.

Sorry, I assumed your position was based on actually having gone through the training on how to teach the maneuver, not just a critical reading of the PTS.

I'm working on lesson plans and thinking in my mind about how I would teach it. I never though of adding power to turn because I "learned" slow flight before the 2002 PTS change when you didn't have to. So I suppose this is how I will have to teach it to students.

Though I just might send a letter to the FAA as you suggested.

 

[Skip Miller]

So I still say the FAA is being boneheaded with their wording. How can you be required to be right on the edge of the stall yet have a tolerance of -0/+10 knots...it's beyond logic to me.

There is the problem right there.... You can't use the words "FAA" and "logic" in the same paragraph.

-Skip

 

[poadeleted20]

Not true. The part I'm having issue with was written that way in 2002 and it hasn't been changed at all since then. Before that, it was completely different:

Only briefly, and before that it was the way it is now, and it was that way for decades before they boogered it into the definition you mention, and after a lot of clamor and discussion, changed it back in 2002.

I'm working on lesson plans and thinking in my mind about how I would teach it. I never though of adding power to turn because I "learned" slow flight before the 2002 PTS change when you didn't have to.

I guess I'm a bit surprised that you never learned about the relationships between AoA, power setting, load factor, bank angle, and speed before this, but it's good that this made you think about the problem.

So I suppose this is how I will have to teach it to students.

That's correct.

 

[dmspilot]

Only briefly, and before that it was the way it is now, and it was that way for decades before they boogered it into the definition you mention, and after a lot of clamor and discussion, changed it back in 2002.

I see...thanks for the insight...

I guess I'm a bit surprised that you never learned about the relationships between AoA, power setting, load factor, bank angle, and speed before this, but it's good that this made you think about the problem.

Where did I say that I never learned the relationship between AoA, power setting, load factor, bank angle, and speed? I'm not stupid. I understand it perfectly. You seem to be projecting experiences with your own students upon me.

 

[poadeleted20]

Where the hell did I say that I never learned the relationship between AoA, power setting, load factor, bank angle, and speed?

When you said you never thought of using power to maintain altitude in turns. Well, perhaps at the rote level, but not at the levels of application and correlation, which is where a CFI needs to be on aerodynamics knowledge.

 

[dmspilot]

When you said you never thought of using power to maintain altitude in turns. Well, perhaps at the rote level, but not at the levels of application and correlation, which is where a CFI needs to be on aerodynamics knowledge.

I KNOW you CAN...but which technique you are supposed to use to meet the PTS on a checkride is not a reflection of whether I "was taught" the relationship between angle of attack and loadfactor...geez. And regardless of how experienced my instructors are, I am perfectly capable of learning on my own. So that was a totally inappropriate question.

 

[bobmrg]

Thanks nosehair and gtcfi and tony...I am just doing the ground work now, so this is all hypothetical, but will try out your techniques next time I do slow flight.


The word "any", to me, means just that: any. Including infinitesimal. So it should say "perceptible increase" not "any increase". Not that I'm getting in a sweat...I just disagree with the FAA and think it's an example of government incompetence.



You are right, it says -0/+10 knots actually. Which IMO contradicts the other standard that comes right before it. So I still say the FAA is being boneheaded with their wording. How can you be required to be right on the edge of the stall yet have a tolerance of -0/+10 knots...it's beyond logic to me.

Golly, Ive signed off a lot of students who must have performed adequately for the DE, and I have administered a whole bunch of checkrides as a DE, and this comes as a surprise to me.....

Trust me...the DE knows what slow flight requires.

Bob Gardner

 

[denverpilot]

Trust me...the DE knows what slow flight requires.

Thank you Bob for the sanity check.

Watching CFIs quibble over FAA wording doesn't exactly project confidence to those of us who'd just like to go demonstrate that we "get it" about how to fly an aircraft around at minimum airspeed.



"Keep it in slow flight just above the edge of the stall and turn to 280" is what the person in the right seat has always said to me. For varying values of 280.

They were probably thinking of the goofy wording in the back of their wonderfully encyclopedic heads, and then using plain non-FAA English to see if I could do it without killing them or myself in the process.

"Don't let the airspeed climb," pretty-well covered the limitations.

 

[BillTIZ]

Re: Contradiction in FAA Slow Flight PTS standards

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

Starting with just straight and level slow flight, it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall, and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

You passed your Pvt and Comm check ride, which both required slow flight.
So it must be possible.

 

[MBDiagMan]

It's interesting how we sometimes take things for granted. Along these same lines, we sometimes learn to do things and not know that they're supposed to be hard.

Both of my instructors, have had me fly on the edge of stalling and make me do an approach with nothing but rudder movement. I thought it was fun and in spite of the fact that I am NOT a natural or talented pilot, was able to do it quite well.

I guess I didn't know it was supposed to be hard so I was able to do it.

Doc

 

[Jaybird180]

It's interesting how we sometimes take things for granted. Along these same lines, we sometimes learn to do things and not know that they're supposed to be hard.

Both of my instructors, have had me fly on the edge of stalling and make me do an approach with nothing but rudder movement. I thought it was fun and in spite of the fact that I am NOT a natural or talented pilot, was able to do it quite well.

I guess I didn't know it was supposed to be hard so I was able to do it.

Doc

What was the point of THAT exercise?

 

[bobmrg]

What was the point of THAT exercise?

Simulates loss of aileron/elevator control? Sounds like a good idea to me.

Bob Gardner

 

[Jaybird180]

Simulates loss of aileron/elevator control? Sounds like a good idea to me.

Bob Gardner

By reinforcing Wolfgang Langewiesche's 'great sin'?

 

[dmspilot]

we sometimes learn to do things and not know that they're supposed to be hard.

I guess I didn't know it was supposed to be hard so I was able to do it.

I didn't say slow flight is hard. I said the PTS doesn't make sense. You didn't read the thread.

 

[MBDiagMan]

I didn't say slow flight is hard. I said the PTS doesn't make sense. You didn't read the thread.

dms,

Sorry about that! My bad. I didn't mean any ill will in what I wrote.

Doc

 

[nosehair]

What was the point of THAT exercise?

To practice rudder control. Many pilots are not taught rudder control, or they get lazy and just 'drive' around with aileron. Exercising rudder only will wake up your feet and get some neurons built that will begin to 'automatically' make your feet and hands work together.

 

[dmccormack]

To practice rudder control. Many pilots are not taught rudder control, or they get lazy and just 'drive' around with aileron. Exercising rudder only will wake up your feet and get some neurons built that will begin to 'automatically' make your feet and hands work together.

Skidding around the pattern teaches that?

 

[RyanShort1]

Skidding around the pattern teaches that?

For real. That's kind of shocking. A Cub or Champ will cure that problem much more effectively, as will a good instructor.

Ryan

 

[dmccormack]

For real. That's kind of shocking. A Cub or Champ will cure that problem much more effectively, as will a good instructor.

Ryan

Exactly. I thought I flew with decent coordination. Until I flew a T-Craft.

 

[steingar]

Re: Contradiction in FAA Slow Flight PTS standards

Working on my CFI certificate and I have to take an exception to this. I do not understand how this task is possible.

Starting with just straight and level slow flight, it seems humanly impossible to me to fly at a speed such that even an infinitesimal increase in load factor or angle of attack will result in a stall, and furthermore seems impossible for the applicant or examiner to determine whether you are on an the infinitesimal edge of a stall or not.

To further make my case, the FAA expects you to conduct turns in this configuration while maintaining altitude. Since it definitely is impossible to turn and maintain altitude without increasing angle of attack or load factor, I say this task is impossible as worded.

You can control altitude with power, which is what you're supposed to do in the pattern anyway.

I can't disagree with the taildragger pilots at all. I fly coordinated in the Cherokee, but I doubt it would be very hard to do with my feet flat on the floor. There just isn't that much rudder authority.

 

[Jaybird180]

I thought you had a Comanche

 

[steingar]

I thought you had a Comanche

I wish.

 

[MBDiagMan]

For real. That's kind of shocking. A Cub or Champ will cure that problem much more effectively, as will a good instructor.

Ryan

Yep, if you want to whip your rudder habits into shape spend a few hours in a Champ.

 

[nosehair]

Re: Contradiction in FAA Slow Flight PTS standards

You can control altitude with power, which is what you're supposed to do in the pattern anyway.

Don't even get me started!

 

[RoscoeT]

Re: Contradiction in FAA Slow Flight PTS standards

Don't even get me started!

What's there to argue with? We all know that the elevator controls airspeed, which is why I furiously pump the yoke on the takeoff roll.