Constant airspeed climb/descent

injb

Pre-takeoff checklist
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jb
I just did my 5th flying lesson today, and I've been having a little trouble keeping my altitude under control. Something that hasn't quite sunk in for me yet is exactly when (and why) you need to make pitch changes with the yoke when you reach the altitude you want, instead of just setting the power to the level that will maintain that altitude.

Looking back at my video from the previous lesson, I see my instructor taught me to start altitude changes with power only, but then "encourage" the nose back to level when we get to where we want, then put the power back to where it should be. But I never got around to asking him why it has to be done that way.

Today I found myself forgetting to encourage the nose down after making a climb to correct my altitude, and I couldn't seem to get it stabilized. I'm trying to form a good mental model of what is really going on so that I can't get it wrong in future, but I could use some help! If I remember what I've been told/shown correctly, you only need to change your power setting in order to begin a constant airspeed climb or descent. But to level out from that climb or descent, you need to do this little "encouragement" with the yoke. Is that correct, or am I still missing something? And if that is correct, why? Surely if your speed was constant up to that point, then the making a pitch change with yoke is going to change it?

It seems like somehow the plane is very willing to depart from level flight, either up or down, but reluctant to come back to it, once the original power setting is restored.
 
Trim exercises will be very beneficial for you. Have your CFI trim the airplane nose up and then trim it nose down and try to maintain altitude with the yoke and power. These exercises will help you learn how trim, power and the yoke coincide with each other.
 
Seems you're over complicating it. I wouldn't try to remember specific numbers as in rpms. If you pull your power to cruise too soon after level off from a full power climb, it'll just take longer to get trim stabilized at cruise speed. If you pitch down before pulling power in a descent you'll just over speed. If you don't get your power back in soon enough after leveling of the descent, you'll get too slow and take longer to get stabilized in cruise.
 
Level off, hold it level, adjust power to cruise, trim.

Observe what your nose position is to the horizon, and use it every time. Eventually it becomes second nature. Hang in there, you'll get it.
 
Thanks for the replies. Everyone mentioned trim funnily enough - I do have trouble getting the plane trimmed correctly, which is part of the reason I end up having to make so many altitude corrections. But I understand the trim, I just haven't gotten used to it yet. But some of the responses here seem to be saying you always adjust pitch first, then power, then trim. That is definitely not what I've been taught so far. For example, in one situation, I had failed to get the trim right, and climbed 700 feet unintentionally. Here's how my instructor showed me how to fix it:

1. Fix the trim for level flight. Now everything is fine except we're 700 feet too high.
2. Reduce power to descend 700 feet
3. Restore the power to approximately where it was
4. Adjust the pitch upwards a little.
(3 and 4 were almost at the same time)
5. Make a few very small corrections since obviously things are not back exactly as they were before.

What I don't understand is, why is pitch control with the yoke necessary at the end of this process, but not at the beginning? It's the same when climbing, from what I've been shown. The plane was trimmed correctly by my CFI at the beginning of the demonstration, so that's not the issue.
 
Not completely understanding what you're meaning but, power adjustment comes first when leveling the airplane at altitude, followed by a trim adjustment. Doing it the opposite is counterproductive.

If you're at 3,000' and you need to descend to say 2,900', a power adjustment isn't normally required. Simply push forward on the yoke a tad, followed by a hair of nose down trim. Once you're coming up to 2,900' then just ease back on the yoke to level the nose and re-trim for level flight.
 
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Interesting.... So I always overshot my cruse altitude by 100 to 200 feet, then keep the power in, push over and drop down to the right altitude, level off and reduce power... then trim to hold that increased speed.... if you just level off at your cursing numbers, the nose will be high, and it will "push" along... not really getting all the speed that could be had... As for maintaining the set altitude, that elusive +/- 200 feet is a game of pitch and trim.... trim, more trim, then trim again....
 
injb, this handbook is going to be your best friend for the rest of your training: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/ . Read Chapter 3.

While climbing, take a look at quick glance at your vertical speed indicator (VSI). If it reads 500 feet per minute, take 10% of that value. The resultant value is 50 feet. Start your level off 50 feet below your target altitude by smoothly applying forward pressure on the yoke. As you do this, look outside at the horizon (and not inside at the gauges). Pitch the nose so that it is slightly below the horizon. Now take a look at the altimeter. If the big hand on the altimeter is still moving clockwise (indicating a climb), pitch down with more forward pressure on the yoke until it stops moving.

Next, while holding that forward pressure on the yoke, reduce power to a cruise setting, usually 2100-2300 RPM during training. Do it fairly quickly so that you can get back to focusing on other stuff. 3-4 seconds is all this should take. Any longer than that and you'll already be climbing again because you're too concentrated on the RPM gauge (aka the tachometer).

Next adjust your trim. If you had the trim set for takeoff on the ground, or had it set for a climb attitude (which is unlikely given your descriptions of what your instructor has been teaching), you will have to trim down. Pretend your hand is on top of the airplane. Moving the trim wheel forward towards the nose will result in the forward pressure you're applying on the yoke being relieved.

1. Pitch.
2. Power.
3. Trim.
 
Not completely understanding what you're meaning but, power adjustment comes first when leveling the airplane at altitude, followed by a trim adjustment. Doing it the opposite is counterproductive.

If you're at 3,000' and you need to descend to say 2,800', a power adjustment isn't normally required. Simply push forward on the yoke a tad, followed by a hair of nose down trim. Once you're coming up to 2,800' then just ease back on the yoke to level the nose and re-trim for level flight.
Pitch, power, trim.

Assuming you're trimmed for straight-and-level flight, an altitude change of 200 feet should be accomplished with a power adjustment in most piston singles. The result of pitching, trimming, and not adjusting the power is that the speed will increase and subsequently result in unexpected performance when the pilot attempts to level off into a normal cruise attitude. In the example of the 200 foot descent, a gain in airspeed that results in trimming down and pitching down (without adjusting power) will cause the airplane to climb when the pilot levels off into a "normal" cruise attitude that actually isn't suitable for that speed.
 
I appreciate all the feedback, but I don't think I've explained what's confusing me.

I understand trim. Let's assume I'm in level flight and trimmed correctly, and I'm happy with my airspeed, but I want to change my altitude. The reason for that might be that I have previously mismanaged my trim, but that's fixed now.

What I have been shown is that I should begin the process with a power adjustment only, but finish it (i.e. return to level flight) by using pitch as well as power. Why is it not enough to simply restore the power to where it was before?
 
Like many have said pitch for cruise speed, set power , and trim. And just keep the mental picture of level. But what do I know. I only have 10 hours lol
 
Having thought about it for a while, I wonder if this is a better way of thinking about it: power is a coarse adjustment for altitude, and pitch is the fine adjustment. You could use pitch as a coarse adjustment, but that would result in big changes to your airspeed as a side affect. Maybe power adjustments are just not precise enough to get the altitude nailed, and that's why you need both? That explains why you would begin a climb or descent with power, but finish it with pitch. It would also mean that having used pitched to fine tune your altitude, you'd be flying at a slightly different airspeed than before, and you have to re-trim. But it would be a small change - a trade off of precise speed for precise altitude control. Does that make sense at all?
 
What helped me immensely in getting this sort of thing right was to stop thinking about in terms of the individual controls, but rather what the controls do to what you actually want to manage: energy. I'm sure you're heard the term "energy management" and that is exactly what you're trying to do at the top of a climb. Ignoring trim for now, think about pitch as a fast way to trade potential energy (altitude) for kinetic (speed) or vice-versa. Power is the slow way to just add or subtract energy, either potential or kinetic (especially in low-horsepower trainers).

At the top of the climb, you have maximum potential energy you desire (for the moment, anyway). But you want more kinetic. You're already pumping maximum power into the energy equation with the engine, so you trade some of that for speed by pitching down. At some point, you get the speed you planned for, so you pull power back to keep the balance of power in the same as the power going out with drag. Along the way, you've adjusted the trim to keep your yoke forces balanced, but trim doesn't play into the energy balance directly. And there you are: level cruise.

Reality, of course, is more complicated. The wing does not respond linearly to yoke inputs and it responds differently at different speeds. How you set the trim can make the job easy or really hard. This is where learned feel comes in. How much do I pitch this aircraft down when leveling? How much trim do I run in at first to keep it there? Now, as speed comes up, the aircraft will attempt to climb again, because speed's effect on angle of attack is not linear. So, gradual pitch down and trim down as the speed comes up to keep the altitude. And, of course, there are multiple orders and techniques to getting it right. For various physical reasons, it's actually just a little faster to reach cruise speed by overshooting your altitude and descending to it. But the effect is minor and not something to worry about in initial training.

Anyway, that's the way I think about it: I have an energy budget, and I can spend it with the controls. The yoke is about trading and borrowing (both pitch and roll). The power is about adding and subtracting. Trim is about stability: spending your energy budget precisely. The rudders are about being efficient with it. Maybe that helps you, maybe I just made it more complicated.
 
...
Anyway, that's the way I think about it: I have an energy budget, and I can spend it with the controls. The yoke is about trading and borrowing (both pitch and roll). The power is about adding and subtracting. Trim is about stability: spending your energy budget precisely. The rudders are about being efficient with it. Maybe that helps you, maybe I just made it more complicated.

OK, but if the power is about adding and subtracting, then why would adding the power that I took away not get me back to the same condition I was in before? Why I should I have to mess with the yoke? That's why I've started to think that it's a question of precision. Restoring the power to where it was *would* get me back to exactly the same condition, but maybe it's impossible to be that precise. Maybe it's easier to set the vertical speed precisely with the yoke, at the expense of a small unwanted change in airspeed.
 
OK, but if the power is about adding and subtracting, then why would adding the power that I took away not get me back to the same condition I was in before? Why I should I have to mess with the yoke? That's why I've started to think that it's a question of precision. Restoring the power to where it was *would* get me back to exactly the same condition, but maybe it's impossible to be that precise. Maybe it's easier to set the vertical speed precisely with the yoke, at the expense of a small unwanted change in airspeed.

I should have been clearer. It's about adding and subtracting energy. That energy can go to either speed or altitude. Your pitch governs how much of that is being added to which variable.

Before everyone else jumps all over me, this is, of course, a simplification. Yes, I could talk about trimming for speed and phugoid oscillations and engineered stability. But for me, those all got blended into the "feel" you pick up with practice. For me, I don't think in terms of absolute power settings, exactly how much pressure on the yoke, or how many turns of the trim. (Big exception: aircraft limits. Know where the limits are and don't exceed them!) Some pilots do think about absolutes and it works for them. Do what works for you.

For me, I know that at the top of the climb, I want to start putting all my energy into speed instead of altitude. So I use the tool for making that trade, the yoke, to effect it by pushing. After doing so, I'm in a loop with the instruments to ensure that it's really doing what I want. I have to keep pushing the yoke more and more with speed to keep the trade correct. There's lots of physics as to why, but I'm not thinking about that. I just know that my energy budget shouldn't be spent right now on gaining altitude, so I'll keep the balance. Along the way, I trim to make myself comfortable.

At cruise speed, I now don't want to keep adding energy at all, speed or altitude. That's where the power comes back. Admittedly, at this point, it is book numbers that are driving me. I know what cruise setting I planned for. This is a case of knowing the limits I mentioned earlier: you want to keep your engine running by not overstressing it, so running along at 100% power is not a good move.

With more and more flying, you add more tools to your toolbelt for managing that energy. S turns, slips, flaps, speed brakes, spoilers, gear, and more.

Anyway, that's me. Others do it differently, and they're not wrong. You will find the thing that works for you!
 
Think of it this way. The mission is to get to cruise. It may be hard to see this with your trainer. However, let's look at a xc traveling machine. You will want to pitch over and let the plane accelerate. Why, because your behind the power curve speed wise. As the plane accelerates you can start reducing power. Once at the speed you want you and set power to maintain it. Other wise the plane is just mushing along and will take a long time to get to your cruise speed if ever. Of course you can trim the pressure off as needed... Now if performance is not what you're after then the Pitch, Power, Trim is what you want to do...

Now that I've said all this, here is my recommendation... Talk to your CFI and do what he wants... That's what's going to matter in the end.:yes:

Keep us posted on you progress...

Fly save,
 
I appreciate all the feedback, but I don't think I've explained what's confusing me.

I understand trim. Let's assume I'm in level flight and trimmed correctly, and I'm happy with my airspeed, but I want to change my altitude. The reason for that might be that I have previously mismanaged my trim, but that's fixed now.

What I have been shown is that I should begin the process with a power adjustment only, but finish it (i.e. return to level flight) by using pitch as well as power. Why is it not enough to simply restore the power to where it was before?

Whether you're talking about a climb or a descent, and the magnitude of the altitude deviation, are going to affect the technique. Give some specific examples.
 
Having thought about it for a while, I wonder if this is a better way of thinking about it: power is a coarse adjustment for altitude, and pitch is the fine adjustment. You could use pitch as a coarse adjustment, but that would result in big changes to your airspeed as a side affect. Maybe power adjustments are just not precise enough to get the altitude nailed, and that's why you need both? That explains why you would begin a climb or descent with power, but finish it with pitch. It would also mean that having used pitched to fine tune your altitude, you'd be flying at a slightly different airspeed than before, and you have to re-trim. But it would be a small change - a trade off of precise speed for precise altitude control. Does that make sense at all?

That does make sense actually. Usually small altitude deviations (about 100 feet) can be corrected with pitch only. Larger altitude deviations call for a power adjustment as well. In straight-and-level flight, altitude is more important than airspeed, don't worry about variations in airspeed so much, it will vary due to turbulence anyway as well as the airplane's natural tendency to oscillate. Also keep in mind that trim is not a cruise control, it's not going to be perfect even in smooth air for more than a couple minutes.
 
Pitch, power, trim.

Assuming you're trimmed for straight-and-level flight, an altitude change of 200 feet should be accomplished with a power adjustment in most piston singles. The result of pitching, trimming, and not adjusting the power is that the speed will increase and subsequently result in unexpected performance when the pilot attempts to level off into a normal cruise attitude. In the example of the 200 foot descent, a gain in airspeed that results in trimming down and pitching down (without adjusting power) will cause the airplane to climb when the pilot levels off into a "normal" cruise attitude that actually isn't suitable for that speed.
Bad example, on my part. I was intending to describe a small altitude adjustment. Post edited to correct.
 
Interesting.... So I always overshot my cruse altitude by 100 to 200 feet, then keep the power in, push over and drop down to the right altitude, level off and reduce power... then trim to hold that increased speed.... if you just level off at your cursing numbers, the nose will be high, and it will "push" along... not really getting all the speed that could be had... As for maintaining the set altitude, that elusive +/- 200 feet is a game of pitch and trim.... trim, more trim, then trim again....

Getting on the "step," eh? Gotta try that soon.
 
Just a thought, but it might be a problem with the "seat of your pants."
During a prolonged climb, your body gets used to the nose up attitude and begins to think that it's "normal". When you push over at the top of the climb, the seat of your pants tells you that now you're in a dive, so you pitch up to get back to what your body considers normal and resume your climb. Eventually, you adapt to level being normal, but the climb-level off-climb sequence is normal for new pilots until they begin to believe the instruments and ignore what they're feeling.
 
injb, this handbook is going to be your best friend for the rest of your training: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/ . Read Chapter 3.

While climbing, take a look at quick glance at your vertical speed indicator (VSI). If it reads 500 feet per minute, take 10% of that value. The resultant value is 50 feet. Start your level off 50 feet below your target altitude by smoothly applying forward pressure on the yoke. As you do this, look outside at the horizon (and not inside at the gauges). Pitch the nose so that it is slightly below the horizon. Now take a look at the altimeter. If the big hand on the altimeter is still moving clockwise (indicating a climb), pitch down with more forward pressure on the yoke until it stops moving.

Next, while holding that forward pressure on the yoke, reduce power to a cruise setting, usually 2100-2300 RPM during training. Do it fairly quickly so that you can get back to focusing on other stuff. 3-4 seconds is all this should take. Any longer than that and you'll already be climbing again because you're too concentrated on the RPM gauge (aka the tachometer).

Next adjust your trim. If you had the trim set for takeoff on the ground, or had it set for a climb attitude (which is unlikely given your descriptions of what your instructor has been teaching), you will have to trim down. Pretend your hand is on top of the airplane. Moving the trim wheel forward towards the nose will result in the forward pressure you're applying on the yoke being relieved.

1. Pitch.
2. Power.
3. Trim.

Best advice so far. Nice and concise.

The way the OP phrased his dilemma - and a few of the suggestions - implied what I think is a bad habit: "Flying the trim". Leveling off from a climb or a descent is actually one of the simpler skills in flying, so no need to over-complicate it. The key is the PIC needs to put the nose where he or she wants it - firmly and with authority - to get the performance desired. Accuracy first; smoothness later. Undercontrolling is as much of a problem as overcontrolling. "Climbing 700 feet unintentionally" certainly implies undercontrolling. Trim only comes into it to relieve control pressure, never to move the nose.

The reason to leave climb power in initially is to accelerate into the cruise regime as efficiently as possible. There is no "step", but it is possible to settle into cruise on the "backside of the power curve" and to dwell there for an entire flight. Not usually a problem until near the plane's ceiling, but it's still a good habit to get into.
 
The way the There is no "step", but it is possible to settle into cruise on the "backside of the power curve" and to dwell there for an entire flight. Not usually a problem until near the plane's ceiling...

It's also an issue (more just an aspect of the plane's handling rather than a problem) in many low powered light planes at any altitude.
 
What I have been shown is that I should begin the process with a power adjustment only, but finish it (i.e. return to level flight) by using pitch as well as power. Why is it not enough to simply restore the power to where it was before?

It IS possible to just use power at both ends of the climb or descent to get back to where you want to be. Absolutely. It just takes longer. From cruise, pull the power back and the airplane will descend, as you know. At the bottom, yes, you could just add power to level off, in fact this is a fine way to do it. But it takes a little longer because you are now overcoming the inertia of the airplane descending. Gravity and all. So if you add just a little bit of back pressure on the yoke as well, it speeds up the transition, and that in turn means you can get on to the next task, whatever it may be, such as navigating, radio use, changing fuel tanks, etc. Try it both ways, you'll see, it works either way.

Same is true in a climb. You CAN do it just by manipulating power, it just might take longer.
 
If you JUST did it with power, it would set off a phugoid oscillation. Try it. Let it go a whole cycle, but be careful not to let the engine or airplane overspeed at the bottom of the cycle (this is best done at low power).

There isn't much damping in the system unless you add it.
 
What I don't understand is, why is pitch control with the yoke necessary at the end of this process, but not at the beginning? It's the same when climbing, from what I've been shown. The plane was trimmed correctly by my CFI at the beginning of the demonstration, so that's not the issue.

Pitch control is not necessary at either the beginning or the end of a climb or descent but is often done to obtain a desired optimal airspeed. To climb, add power, pitch up, trim. To level off, pitch down, reduce power, trim. After a while, you'll do both pitch and power adjustments simultaneously.

As someone has said, I think of all of this as energy management. Power controls total energy. Pitch controls the distribution of this total energy into potential (altitude) or kinetic (airspeed). To change altitude by only 100 feet or so, I can just keep the same total energy and just redistribute kinetic into potential (pitch up, climb, but also slow down) or potential into kinetic (pitch down, descend, but also speed up). To change altitude by a lot, I also want to change the total energy, hence power adjustment. Then adjust pitch to get the desire distribution.

This concept is crucial when landing and is, to me, more helpful than the simple "pitch for airspeed, power for altitude." If you're slow and high, just try distributing potential into kinetic while keeping the same total energy. If you're fast and low, kinetic into potential. If you're low and slow, increase total energy first then redistribute as necessary. If you're high and fast, decrease total energy first then redistribute as desired.




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It IS possible to just use power at both ends of the climb or descent to get back to where you want to be. Absolutely. It just takes longer. From cruise, pull the power back and the airplane will descend, as you know. At the bottom, yes, you could just add power to level off, in fact this is a fine way to do it. But it takes a little longer because you are now overcoming the inertia of the airplane descending. Gravity and all. So if you add just a little bit of back pressure on the yoke as well, it speeds up the transition, and that in turn means you can get on to the next task, whatever it may be, such as navigating, radio use, changing fuel tanks, etc. Try it both ways, you'll see, it works either way.

Same is true in a climb. You CAN do it just by manipulating power, it just might take longer.

If you JUST did it with power, it would set off a phugoid oscillation. Try it. Let it go a whole cycle, but be careful not to let the engine or airplane overspeed at the bottom of the cycle (this is best done at low power).

There isn't much damping in the system unless you add it.

I have tried it, and I couldn't get it to settle in the altitude I wanted! Now I have a better idea of why. A few posts ago I mentioned my theory that it has to do with being precise, but from what you guys are saying (and I think you're both saying essentially the same thing) it sounds like even if I could get the power back to exactly where it was before, it would still oscillate. This is definitely the best explanation I have heard so far :)

I never waited long enough to see if it would eventually stabilize because my CFI just went straight to showing me the proper technique. Which is fair enough, but I wanted to understand it more clearly.
 
Climb under full power to cruise altitude. Then do everything at once. Pull the power back, pull the prop back, lean to rpm drop and richen a bit, and trim to level cruise. Continue to trim a bit as speed is gained in level flight. Rudder, elevator and ailerons as needed of course. Trim as needed, all the time.
 
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Climb under full power to cruise altitude. Then do everything at once. Pull the power back, pull the prop back, lean to rpm drop and richen a bit, and trim to level cruise. Continue to trim a bit as speed is gained in level flight. Rudder, elevator and ailerons as needed of course.

That may work for you most times, but is not traditionally how it's done, as outlined previously.

From the AFH:


"After the airplane is established in level flight at a constant altitude, climb power should be retained temporarily so that the airplane accelerates to the cruise airspeed. When the airspeed reaches the desired cruise airspeed, the throttle setting and the propeller control, if equipped, should be set to the cruise power setting and the airplane re-trimmed."

(Bolded mine)
 
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My way is setting the power to a specific manifold pressure and the prop to a specific rpm (the manifold pressure goes UP as the rpm comes down btw). I use these because this is where the engine runs smoothly and I know the fuel burn. The airspeed is whatever airspeed results. At any rate, with my method, I only have to do everything once (except trim). Pretty much have to trim frequently no matter what you do, unless you have an autopilot. Obviously there is no reason the pilot cant make little adjustments along the way. Or big ones, if that is what is wanted.

Watch the CHT's in the climb and don't let them get too high. Might need an adjustment there also.
 
Best advice so far. Nice and concise.

The way the OP phrased his dilemma - and a few of the suggestions - implied what I think is a bad habit: "Flying the trim". Leveling off from a climb or a descent is actually one of the simpler skills in flying, so no need to over-complicate it. The key is the PIC needs to put the nose where he or she wants it - firmly and with authority - to get the performance desired. Accuracy first; smoothness later. Undercontrolling is as much of a problem as overcontrolling. "Climbing 700 feet unintentionally" certainly implies undercontrolling. Trim only comes into it to relieve control pressure, never to move the nose.

Yes it's a "simple" skill the way you described it (put the nose where you want it), the less simple parts are knowing where you want it, sensing the difference between that and where it is, and determining how much control pressure is needed to reduce that difference to zero.

I did sense that the OP is missing the point that while there's a specific recommended sequence for pitch and power changes when leveling off from a climb, the reaction of the airplane to changes in either elevator force/position and power is not independent. Instructors tend to provide a simplified explanation of this such as "pitch controls airspeed, power controls altitude (or climb rate)" but most airplanes don't behave that way on their own. IOW if an airplane is flying level at some speed with zero elevator force input by the pilot (i.e. in trim) and you add power without applying any force to the wheel, the airplane will change all three of pitch attitude, climb rate, and airspeed with different response times for each.

All of this comes into play when "simply" leveling off and there are multiple ways to deal with it. Fast Eddie's recommendation is a good strategy though but I think it needs further explanation:

1) It's already been posted that the reason you leave the power alone at first is because you want to use the excess power to increase airspeed. You could reduce the power immediately to what's needed for your intended airspeed in level flight but the airplane's speed increase would be so gradual you might not get to the target speed before your fuel ran out. So leave the throttle alone until you get to the speed you want. Of course this assumes you know what that speed is.

2) You definitely need to pitch the nose down some but it's not really obvious how much or how quickly this needs to be done. Changing pitch more rapidly than necessary (i.e. without "smoothness") is undesirable because it's uncomfortable for passengers and therefore something you should strive for but as Fast Eddie suggested you'll learn faster if you focus on accuracy (getting the right pitch attitude) first. That said, if you're way to abrupt you can overcontrol to the point that the pitch attitude keeps changing up and down rapidly (Pilot Induced Oscillation) and this must be avoided for all sorts of reasons.

3) The "perfect" pitch attitude during the level off is not a constant, even in smooth air. Initially you need to pitch down just enough to stop climbing but as the airplane speeds up you need to lower the nose even further because as the speed builds the wings need less angle of attack to generate enough lift to hold altitude. In addition, the elevator force on the wheel increases with speed (fairly dramatically) even if you just hold the exact same pitch attitude. This is why trimming during the level off is necessary. But during the level off while the speed is still changing (i.e. before you reduce power) you don't need to get the trim "perfect", just close enough that the residual elevator force required is easy to manage.

4) Since airspeed builds slowly your focus during the leveling off process needs to be in this order: Pitch, Altitude, Trim (coarse), Airspeed, Power. Pitch is first because if your pitch is off by as little as 1° your altitude will change fairly rapidly. Altitude is next because that's what's supposed to be constant. Correct (coarse) trim is helpful but not essential (it's possible to perform an accurate and smooth level off without touching the trim but it's a lot more work and considerably more difficult in most airplanes). Unless someone replaced your engine with something with twice the HP it will take several seconds (or even minutes at high altitudes) for the airspeed to reach your target and the only thing you need to do when that happens is reduce power so an occasional glance at the ASI is all that's needed. Finally the throttle should just sit there fully open until the target speed is reached so it get's the least attention, until the airspeed hits the target.

5) Once you've set cruise power and are holding altitude it's finally time to set the trim as close to optimal as possible. You do this by holding as light a grip on the wheel as possible while maintaining the pitch attitude that results in zero climb (the smoother the air, the lighter the grip) and sensing the average pressure on your thumb and finger then making small changes in the trim to get that average force to zero. During this time you should be holding your target altitude as well although as long as the altitude excursions are small (less than 50 ft) and very gradual they won't affect the trim enough to matter and once you get the trim correct you can return to the exact altitude with very light elevator pressure and minimal changes in airspeed.


BTW, IMO there's nothing wrong with "pre-adjusting" the trim to get it close to the eventual setting when you are deliberately changing attitude, or power. Of course to do that you need to have a pretty good idea of how much trim change is necessary and that requires experience (the pilot's or his instructor's).

The reason to leave climb power in initially is to accelerate into the cruise regime as efficiently as possible. There is no "step", but it is possible to settle into cruise on the "backside of the power curve" and to dwell there for an entire flight. Not usually a problem until near the plane's ceiling, but it's still a good habit to get into.

A bit off topic but the true "backside of the power (required) curve" occurs between stall speed and minimum sink speed which is generally only a few knots above stall speed so unless you're flirting with the airplane's absolute ceiling (something no student should ever do) or practicing slow flight this doesn't have anything to do with leveling off.
 
Thanks for taking the time to expand on my point - it may take a while for me to digest all of it.

Finding the pitch for level cruising flight is important. An instructor needs to point out what it looks like. It may be a certain distance between the panel or cowling and the horizon*. Or it could be where the horizon bisects the windshield pillar. In the latter case a piece of tape strategically located somewhere on the pillar can help.

Yes, it will change a bit. But level off in a Cessna 150, let's say, at a normal altitude and set 2400 rpm and an instructor needs to give a student a good idea of what the pitch should look like as a starting point.

I hope the OP's instructor has not omitted this valuable step.


*When I transitioned Cessna pilots to either my Citabrias or Grummans, they would almost invariably climb when attempting to level off. Both planes had much lower panels than the typical Cessna, and they would attempt to use the same cues that had worked for them there. I had to coax them to look at the wings to confirm we weren't in fact "flying downhill" and encourage them to find new cues for level flight. Same thing now applies to most pilots flying my Sky Arrow for the same reason. In level flight:

29035344085_5b1972e9bd.jpg
 
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A bit off topic but the true "backside of the power (required) curve" occurs between stall speed and minimum sink speed which is generally only a few knots above stall speed so unless you're flirting with the airplane's absolute ceiling (something no student should ever do) or practicing slow flight this doesn't have anything to do with leveling off.

True. But the Law of Primacy should have us teaching correct procedures from the get-go.

Power back too soon in an SR22 at altitude and you could fly along for hours at 155kts where the same power setting could have resulted in 165kts if the plane had been allowed to accelerate at climb power as the AFH recommends. It's not a "step", but it can sure feel like one.
 
Lol I'm amazed at how much my question has been misunderstood.

People are still talking about how to get the plane into level flight, and how to get to the airspeed I want, and how to trim, even though the the starting point for my question was a plane in level flight, properly trimmed, and traveling at the airspeed I want. The altitude is the only thing I wanted to change in my example.

For anyone who's not sure what I was asking, I'll just point out that my question was answered in posts #26 and #27. If the answers themselves don't make it clear what my question was, then I give up lol :)

That's not to say that I'm not delighted with all the replies of course - I really do appreciate it all and I don't doubt that there's a lot in there that I can learn from.
 
True. But the Law of Primacy should have us teaching correct procedures from the get-go.

Power back too soon in an SR22 at altitude and you could fly along for hours at 155kts where the same power setting could have resulted in 165kts if the plane had been allowed to accelerate at climb power as the AFH recommends. It's not a "step", but it can sure feel like one.
The only difference if you reduce power before reaching 165 kt is that it will take longer to reach that speed assuming your final power setting. If you set that power while at 150 kt you should get to within one knot of the final 165kt in several minutes or less. Technically that last knot or so will take "forever" because the difference between power required and power produced is so small that you'd actually have to burn off some fuel weight to actually hit 165 kt but there's no way you'd be "stuck" at 155 kt for "hours". Physics says this is simply not possible and the power required to cruise at 165 KTAS in a SR22 is approximately 20% more than what's required at 155 KTAS under identical conditions. Another way of looking at that is that with enough power to maintain 165 KTAS (about 65% @ 8000 ft IIRC) while flying at 155 KTS, you've got about 40HP (20% of 65% of 300) left over to accelerate.

I have seen where a pilot will accelerate an airplane to some cruise speed at full power then reduce power to something slightly less than what's needed to maintain that speed and mistake the very slow decline in speed for a higher constant cruise speed but there's no free lunch there either.
 
Lol I'm amazed at how much my question has been misunderstood.

People are still talking about how to get the plane into level flight, and how to get to the airspeed I want, and how to trim, even though the the starting point for my question was a plane in level flight, properly trimmed, and traveling at the airspeed I want. The altitude is the only thing I wanted to change in my example.

For anyone who's not sure what I was asking, I'll just point out that my question was answered in posts #26 and #27. If the answers themselves don't make it clear what my question was, then I give up lol :)

That's not to say that I'm not delighted with all the replies of course - I really do appreciate it all and I don't doubt that there's a lot in there that I can learn from.

OK, that wasn't clear in your post and to be honest I'm still not sure exactly what you're asking now. Specifically are you talking about the total process of going from level cruising flight at some altitude and climbing (or descending) a couple thousand feet and then leveling off at the exact same speed (indicated or true?) at the new altitude?

Or did you want to know what to do when you've been cruising along and find yourself one or two hundred below (or above) the intended altitude and want to correct back as quickly or efficiently as possible?
 
Stipulate to all that.

The point is that the Power Required Curve flattens out a lot at altitude. There are two airspeeds on it that require the same power. I still think that's why one leaves in climb power until cruise speed.

One can demonstrate this "ad absurdum" in slow flight. There's a speed where full power will result in maximum level flight speed. But one can practice slow flight and find oneself so slow that full power is also required. In that case the difference is obvious. In a plane close to its service ceiling, it may not be so obvious and, yes, you can get stuck at the slower airspeed. I believe that's the origin of the "step" mythology.

In this diagram, a plane could sustain full power flight at the two speeds where the blue and green lines cross. Once firmly ensconced at the slower speed and full power, there would be no excess power left to accelerate.

Vy3.png


We're pretty deep in the weeds here, but hopefully it can be of benefit to some, if not the OP.
 
I just did my 5th flying lesson today, and I've been having a little trouble keeping my altitude under control. Something that hasn't quite sunk in for me yet is exactly when (and why) you need to make pitch changes with the yoke when you reach the altitude you want, instead of just setting the power to the level that will maintain that altitude.

Looking back at my video from the previous lesson, I see my instructor taught me to start altitude changes with power only, but then "encourage" the nose back to level when we get to where we want, then put the power back to where it should be. But I never got around to asking him why it has to be done that way.

Today I found myself forgetting to encourage the nose down after making a climb to correct my altitude, and I couldn't seem to get it stabilized. I'm trying to form a good mental model of what is really going on so that I can't get it wrong in future, but I could use some help! If I remember what I've been told/shown correctly, you only need to change your power setting in order to begin a constant airspeed climb or descent. But to level out from that climb or descent, you need to do this little "encouragement" with the yoke. Is that correct, or am I still missing something? And if that is correct, why? Surely if your speed was constant up to that point, then the making a pitch change with yoke is going to change it?

It seems like somehow the plane is very willing to depart from level flight, either up or down, but reluctant to come back to it, once the original power setting is restored.

Not to change the subject or anything, but why is a ten-hour student doing constant speed climbs and descents? Fodder for the basic instrument student, but not for a primary student IMHO. I have no quibble with teaching the pitch-power-trim sequence.

Bob
 
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