Starting a New Arguement

[Bob - S50]

Easily proven: set 23", 2400 rpm. Trim for level flight. (Trim = pitch)

Reduce power 2". Don't touch anything else.

Airplane descends, airspeed stays the same.

Therefore power = altitude

And pitch = airspeed.

Easily proven:

 

Sit on the end of the runway, push the yoke all the way forward.  When the speed reaches 65 knots push the power up and climb.

(With tongue fully in cheek)

 

Bob

[Bob - S50]

I let it go - I figured Bob must be from England or someplace else where they don't talk Murican proper.  And I thought maybe we were talking about aeroplanes or something.

Nope, just a bad speller.

 

Bob

[Bob - S50]

I look at this differently and I have had discussions with some CFI/CFIIs on other forums on this topic. If you are maintaining level flight and at say 100 knots and want to increase your airspeed (let's say to 120 knots), the first thing you do is pitch down to increase airspeed (from the original premise that pitch controls airspeed and power controls altitude). As soon you do that, you are moving into a higher energy regime (i.e maintaining same altitude but demanding 20knots more airspeed). If you don't do anything about it (i.e. add power), you are going to go down. It has nothing to do with the fact that you pitched down that you are going down. It has to do with total energy. So you add power to maintain the altitude.  On the ILS you may be going down at 500fpm at say 90 knots, if you want to go slower, you pitch up. Now you have too much energy (same rate of descent desired), so you cut some power until you see the same -500fpm again. I think for long term stable flight this is the right way to fly and there is no confusion on what controls what. It is always pitch for airspeed and power for altitude. As Langewiesche in Stick and Rudder points out, you can achieve anything short term by pitching up or down to change your altitude but that is not a stable situation. I will stick with Langewiesche says and ignore what CFIs say if anything different from this! In practical flying it has worked perfectly for me and it has made me a better pilot. I have an AoA as well which is nice to have and definitely has some benefits in high work load situations.

If I understand you, with all due respect, BS.

 

You really think in your first example that you descended because your mind said it wanted to go 20 knots faster and not because you pushed on the stick?  It had everything to do with the stick.  You cannot change energy state with the stick, you can only convert potential energy to kenetic energy or vice versa.  The only device in the plane that allows you to change energy state is the throttle (because it converts more or less 100LL to hot air).

 

In your second case, if I'm on glidesplope and fast, I'm sure as heck not going to raise my nose and go above glideslope to slow down and then have to reduce power to work my way down again.

 

Pitch has an ...immediate... affect on altitude and a slightly delayed noticable (did I spell that right?) affect on speed.  That is, according to physics, the affect is immediate but it takes a short time until the change is large enough for us to notice.  Power has a somewhat slower affect on speed (but still faster than pitch) and an even slower affect on altitude.

 

I use the yoke to make the airplane go where I want it to go and the throttle as necessary to keep the speed I want.

 

Bob

[yvesg]

I remember when I was trained on visual approaches in a Cessna 150 18 years ago. I had some trouble making it to the right spot... at some point, my instructor slammed me and said touching the yoke: this is the speed... then he pointed to the throttle and said, this is the altitude. On that single day, I started making perfect approaches and have not had any trouble since... so I am sorry guys but I will keep using his coaching.

Yves

[wishboneash]

If I understand you, with all due respect, BS.

 

You really think in your first example that you descended because your mind said it wanted to go 20 knots faster and not because you pushed on the stick?  It had everything to do with the stick.  You cannot change energy state with the stick, you can only convert potential energy to kenetic energy or vice versa.  The only device in the plane that allows you to change energy state is the throttle (because it converts more or less 100LL to hot air).

 

In your second case, if I'm on glidesplope and fast, I'm sure as heck not going to raise my nose and go above glideslope to slow down and then have to reduce power to work my way down again.

 

Pitch has an ...immediate... affect on altitude and a slightly delayed noticable (did I spell that right?) affect on speed.  That is, according to physics, the affect is immediate but it takes a short time until the change is large enough for us to notice.  Power has a somewhat slower affect on speed (but still faster than pitch) and an even slower affect on altitude.

 

I use the yoke to make the airplane go where I want it to go and the throttle as necessary to keep the speed I want.

 

Bob

 

Fine. As you wish. One has to make the power adjustments quickly enough or almost simultaneously to avoid ballooning or undershooting, but that doesn't change the physics or the aerodynamics. By the way, I agree with your statement that you cannot control energy with the "stick" and I never said that you control energy with the stick.

[Bob - S50]

Looks like I am in the minority.

 

I think either way will work and I think we all end up at the same point, we just use a different mindset to get there.  If I'm in the base turn, on speed, but a little high, I push the nose down and simultaneously pull power to avoid getting fast.  Those of you in the wrong (kidding) camp pull the power to go down and simultaneously lower the nose to avoid getting slow.  We both moved both controls at the same time.  Its just a matter of which came first, the chicken or the egg.

 

We all accept the fact that a change in one will usually require a change in the other.

 

I prefer to use one technique for the entire flight and not different techniques for different phases of flight.

 

With that said, for those of you in the majority camp, consider the following scenarios to see if you ...really... use pitch for airspeed control:

 

1.  You are approaching the VFR pattern at pattern altitude doing 140 KIAS.  You want to slow to 100 KIAS to fit in with the other traffic.  Do you really pull the nose up and climb above pattern altitude to slow down as your first action and then pull power to maintain altitude or do you pull power to slow down and use pitch as needed to maintain altitude?

 

2.  You are on final and you have the glideslope nailed.  It is so perfect that Bob Hoover would be impressed.  However, you are 15 knots too fast.  Is your first action really to pull the nose up to slow down, get above that perfect glideslope, then pull power to descend?  Or is your first reaction to pull power and then use pitch to maintain the path?

 

Bob

[WardHolbrook]

I look at this differently and I have had discussions with some CFI/CFIIs on other forums on this topic. If you are maintaining level flight and at say 100 knots and want to increase your airspeed (let's say to 120 knots), the first thing you do is pitch down to increase airspeed (from the original premise that pitch controls airspeed and power controls altitude). As soon you do that, you are moving into a higher energy regime (i.e maintaining same altitude but demanding 20knots more airspeed). If you don't do anything about it (i.e. add power), you are going to go down. It has nothing to do with the fact that you pitched down that you are going down. It has to do with total energy. So you add power to maintain the altitude.  On the ILS you may be going down at 500fpm at say 90 knots, if you want to go slower, you pitch up. Now you have too much energy (same rate of descent desired), so you cut some power until you see the same -500fpm again. I think for long term stable flight this is the right way to fly and there is no confusion on what controls what. It is always pitch for airspeed and power for altitude. As Langewiesche in Stick and Rudder points out, you can achieve anything short term by pitching up or down to change your altitude but that is not a stable situation. I will stick with Langewiesche says and ignore what CFIs say if anything different from this! In practical flying it has worked perfectly for me and it has made me a better pilot. I have an AoA as well which is nice to have and definitely has some benefits in high work load situations.

You're not disagreeing with me, you're disagreeing with that the FAA has published. (Ref: Instrument Flying Handbook Page 4-6.) You're also diagreeing with the way the most precise pilot I know (Otto Pilot) flys any airplane he's in. 

[wishboneash]

The key phrase is "long term". If you are close to the ground, have a certain profile to fly, one has to do what it takes to meet the short term flight profile. I do that myself. So I am not disagreeing with most of you  . If things are less hurried, yes, I will level off by pitching up to reduce speed as I approach an airport several miles out, put the gear down and so on. If you are 300 ft AGL, nailed the GS and you have to reduce speed, by all means go ahead to reduce power first and pitch down to avoid going below the GS, but I don't do that 3 miles from the runway.

[Robert C.]

What I think I'm missing from most of these posts is 2 things: 1) what is the "rule" you follow vs what is your "habit" and 2) an explicit appreciation for the need to do different things at different points in the flight.

 

The fact that the FAA in the IFR Handbook, and your autopilot, all use pitch to stay on glideslope during an ILS approach is all good and well but I'll bet that a 777's Otto uses a different rule set in autoland mode when flaring and landing and that the IFR Handbook doesn't discuss pitch vs power when in the flare.

 

So I'll encourage all of you once again to google Don Kaye's comments on Precision Flying.

 

The "rule" he lays out is simplicity itself:

 

1) Pitch controls whatever is most important at a particular stage in the flight

2) Power controls the other.

 

In cruise and in the pattern you need to maintain an altitude: pitch for altitude, power for speed

In early approach: staying on glideslope is primary: use pitch and then adjust power (the oft cited ILS/Otto example)

Final Approach: you all know what the Mooney does when you're too fast over the numbers and besides, a stall on final is a death warrant: post-FAF, 1 mile out or so, transition to pitch for speed and power for glideslope

 

The rule works in all flight regimes and is incredibly intuitive. When you read all the comments above you quickly see that pretty much everyone does the common-sensical thing anyway, this simply gives the framework.

 

So back to the original inspiration: the dreaded base-to-final turn.

 

What governs? AoA of course.

What tools do we have to control AoA? Both pitch and power, but a pitch change is a lot quicker to effect than a power (speed) change. So i would argue that pitch is "primary." 

So I'd use pitch to maintain the AoA and power to raise or lower my flight path.

 

R.

[Hank]

Good answer, Robert! Our flight path is determined by AoA. What factory instrument provides AoA reading to the pilot? "Nuttin, honey." Airspeed is an approximation, and your load can throw it completely off. Off one way, you land fast and long, hopefully without PIO or prop strike. Off the other way, stall / spin and die.

[kmyfm20s]

Sounds a lot like the "Chicken and the Egg" debate.

[PTK]

...You cannot change energy state with the stick, you can only convert potential energy to kenetic energy or vice versa. The only device in the plane that allows you to change energy state is the throttle (because it converts more or less 100LL to hot air)...

In your second case, if I'm on glidesplope and fast, I'm sure as heck not going to raise my nose and go above glideslope to slow down and then have to reduce power to work my way down again.

I use the yoke to make the airplane go where I want it to go and the throttle as necessary to keep the speed I want.

Bob

I really think the use of the term "speed" or "airspeed" is not proper when we say we use throttle or thrust to control "speed." I think we all use throttle to control the energy conversion. How much potential energy we allow to be converted to kinetic and vice versa. We use pitch to stay on path and control energy with throttle.

A precisely flown GS is one in which this energy conversion is very smooth. No large excursions either way.

[ryoder]

I am kind of low time but I think for vfr work the answer is it depends. If you are aiming right at the numbers but are high then reduce power. Don't change the aim point.

[Jeff_S]

To continue in my vein of incredibly helpful additions to this thread, unfortunately Bob, noticeable DOES have an "e"!

 

Also, somewhat in tune with Don Kaye's maxim, I don't think you can have one solid rule for pitch vs. power because it varies by flight regime.  The successful pilot has learned how to manipulate both to achieve the desired result.

[PTK]

As for the chicken or the egg question, which came first: Y that can't come without X, or X that can't come without Y?

[xcrmckenna]

I would say for precision flying they go hand and hand. But my instructor told me if your engine quits running at 10,000 feet you will not be able to maintain your altitude, but you can carry your speed all the way to the scene of the crash.

[Robert C.]

As for the chicken or the egg question, which came first: Y that can't come without X, or X that can't come without Y?

 

That depends on whether you're in the male or female flight regime of chicken flight.

 

In the male it is XY and in the female XX. Although i will admit I never did understand why it had to be XY rather than YX.

 

R.

[carusoam]

Gregor Mendel decided one day while growing Pea plants...XY vs.YX...?

-a-

[aviatoreb]

As for the chicken or the egg question, which came first: Y that can't come without X, or X that can't come without Y?

 

X if and only if Y. 

[Hank]

Oh oh---the mathematician has entered the (genetics/nature v nurture) debate.

Point if irder, Erik: "IFF" is what you meant, right? X IFF Y.

Reduce throttle slightly IFF too high, maintain yoke position for correct speed; when back on slope, increase throttle a tad (not as much as the reduction). Slightly increase Down trim IFF on slope but getting slow. Etc.

[aviatoreb]

Oh oh---the mathematician has entered the (genetics/nature v nurture) debate.

Point if irder, Erik: "IFF" is what you meant, right? X IFF Y.

Reduce throttle slightly IFF too high, maintain yoke position for correct speed; when back on slope, increase throttle a tad (not as much as the reduction). Slightly increase Down trim IFF on slope but getting slow. Etc.

 

Yes -X IFF Y is short hand for X if and only if Y meaning one implies the other and vice versa - or sometimes its said X is necessary and sufficient for Y.  Its logical speak.

 

So I was in jest deliberately interpreting what was clearly suggesting genetics in terms of language of another topic - logic.  In genetics you can have XY as a genetic trait.  Different story. Just having fun.

[Hank]

Yes -X IFF Y is short hand for X if and only if Y meaning one implies the other and vice versa - or sometimes its said X is necessary and sufficient for Y. Its logical speak.

So I was in jest deliberately interpreting what was clearly suggesting genetics in terms of language of another topic - logic. In genetics you can have XY as a genetic trait. Different story. Just having fun.

[Dave Marten]

For me it is this:

To control airspeed I use pitch

To control altitude (during an approach) I use throttle

Actually the opposite of you Bob!

Yves

Yves, and believe it or not that actually works south of Canada in ambient temperatures above freezing!

 

If you're stuck on the ground waiting on the weather this winter "Aerodynamics for Naval Aviators" has a lot of great info. Available as a free .pdf from our friends at the FAA

 

http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80t-80.pdf

 

or if you use foreflight its one of the documents available for download on the 'download' page.

 

Chapter 6 starting on page 349 has good info for this topic. Heck, the document is written for Naval Aviators so don't be too intimidated.

 

Keep it simple, plan for that stable approach, you'll then be able to easily stay ahead of the pitch/power problem. 

[yvesg]

Thanks Dave for providing this reference. Guys, go ahead and read this. Here is an excerpt about airspeed control...

Yves

[Hank]

That's just what we've been saying, Yves. Pitch for speed, leaving power for altitude.