Like many GA pilots, I learned the “pitch for airspeed, power for altitude” (Navy) method of flying. Soloing in a Taylorcraft, owning a Champ and flying gliders (no extra power) initially enforces this paradigm. And the ancient FAA AC recommending this paradigm (61-50A) is actually still in effect promoting this control method.
The “big iron” (Air Force) answer to aircraft control is exactly the opposite (lots of power available) “pitch for altitude and control speed with power.” Ironically, either paradigm will actually work “most of the time,” but both will also fail in various configurations (Stricklin crash at Mt. Home)
A much more effective – smoother and safer – method of aircraft control is “comprehensive energy management.” “Energy management” has appeared in the FAA testing standards for many years, but only recently, with the new Chapter Four in the Airplane Flying Handbook, do we have solid FAA guidance on how to apply (and teach) this method of control (see also the excellent AOPA article HERE and Ed Kolano).
Your student is low and fast on their final. You burned into their brain “pitch for airspeed” so the power comes in to correct (low) and the plane obediently regains the glide slope (and more). Since we are fast, (and now high too) the student pitches up to correct that; and an unstable dance of rote responses ensues.
Low and fast is a simple “energy management (EM)” issue fixed by a little back pressure (pitch); a comprehensive EM solution provides a smoother, faster and safer result. High and slow same, pitch to fix. Low and slow needs more total energy (power) as does fast and high. So the answer to the pitch/power debate is (in the center of the maneuvering envelope) is “it depends!)
Instead of providing (applying) dogmatic absolutes for glidepath or speed correction, the savvy educator starts with “your control usage depends on your energy status.” Refer to the clever four-part diagram below as an essential starting point for learning (or teaching) this method. Hopefully, this diagram will start appearing in initial CFI lesson plans?
The first step in control is maintaining an awareness of the aircraft’s “total energy.” Excessively high and fast or low and slow requires power management (total energy adjustment). Excessively high and slow or low and fast requires pitch management (energy transfer). Most configurations in between require a pitch and power combination depending on the specific desired performance. This comprehensive (correlative) energy paradigm results in much smoother and safer flying. I have also found that teaching in this manner results in much faster and more accurate student progress (old dog learns new tricks).
A “power-off 180” is not what we want in an emergency – no “safety margin.”
Very often in training (and flight tests) what we see if we simulate an engine failure on the downwind is some version of the “commercial 180” accuracy landing aimed at the end of the runway. This is the wrong maneuver for a real emergency situation (common confusion though). What if we misjudge our energy and end up short of the emergency field? There is no safety margin here or recovery option; game over, no replay! The lack of any extra energy (altitude only please) also precludes any final optimization of the touch-down point on a short final.
In an emergency landing scenario, we absolutely must “make the field” and there are two very common errors in training and flight tests that assure failure. The first error is a huge non-standard pattern usually with a five-mile final. Instead, step one is “go directly to the field” then spiral down (over the field) to a normal downwind position (familiar picture, predictable results). Step two is to aim toward the middle of the field with normal approach speed. You already “made the field” with the downwind key position, we now want to make this as “normal” as possible. The two differences are aim to the middle and reserve the last flaps (and the option of a slip) to “dump energy” (extra altitude not extra speed) at the last moment to optimize the precise touchdown point.
Only on a short final will you detect last-minute obstacles like ditches and wires. The extra altitude (energy) permits some optimization of your intended crash site. BTW: In these situations, most people visualize a “landing” but this will usually be rough – a “crash!” Your plane will probably not roll far at all in vegetation or rough terrain and flipping over is common in high-wings. Mentally visualizing a “survivable crash” will better focus your attention on tightening the belts, shutting down the plane, and assuring a safe exit. Fly safely out there (and often).
The follow-on SAFEblog was written by Rich Stowell applying "first principles" to this endless pitch/power debate (very helpful). In the final analysis (and when out of the center of the maneuver envelope), a different mental model is useful (how every aerobatic pilot flies...) See this blog.
SAFE is everywhere at #OSH22. Our booth is in the Bravo Hangar #2092/3 and the SAFE dinner is on campus at the EAA Partner Resource Center. All readers of this blog are invited to dinner; tickets here!
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Just a note on Stricklin;
His issue wasn’t so much a pitch/power issue as it was that he simply blew his high energy gate number. He reversed on his reverse 1/2 Cuban early and fast thus increasing his turn radius on the downline to the point where ground contact was inevitable.
On pitch/power; The overall problem is that many instructors teach the two components separately and stop short of stressing that the two components are inextricably linked so that one always affects the other. Students shouldn’t be taught the two components without linking them into a more fluid understanding of how the two interact on approach.
Everything connected with flying an airplane is fluid. Teaching the components without teaching how the components interlink together creates a rigid impression for the student on how things work when flying.
Exactly; thanks Dudley. We have been teaching a “rote formula” when “Everything connected with flying an airplane is fluid” (and interconnected) 👍
Great Article. Been teaching that for years and as an SAE, I make sure that all my CFI applicants can teach that. 90% can’t
See Dudley’s comment, most CFIs teach a “rote” solution instead of “nuanced reality.” If you are not taught fully (I was not) it takes years to figure this out. AFH chp. 4 is a good start.
it never ceases to amaze me how you bring something up when I have been discussing it with a student. Was out with an aerobatic student today and talking about energy gain (engine), energy loss (drag), and energy exchange between potential (altitude) and kinetic (speed). It works on final too.
As for emergency landings, we want to arrive near to, and parallel to, the surface, a minimum energy state. One of the issues is understanding that energy is energy. I am going to arrive with more kinetic energy (low and fast) or more potential energy (high and slow). Of course, if one arrives with too much total energy (too high/too fast) one cannot bleed off enough energy to arrive at the landing site with just enough energy. One of the more difficult things to teach is the transition from high kinetic energy during glide to lower kinetic energy to “arrive”. Most figure that out too late. I teach high-key/low-key because it allows the pilot to evaluate and correct energy state at several points, ensuring the correct energy state at the runway.
One thing I would like to see/hear CFIs change is explaining what changes when one moves the elevator. What changes is AoA, which changes lift. Pitch therefore changes as a result of the change in lift. Climb and descent are best described in terms of energy given how our airplanes tend to exhibit AoA trim stability. Applying power in unaccelerated flight causes initial acceleration along the longitudinal axis. The lift formula says that, if the AoA doesn’t change (AoA trim stability) the increased airspeed will result in an increase in lift, and therefore acceleration along the lift vector, i.e. climb. Airspeed decreases back to where it was at equilibrium (or close) and the aircraft stabilizes in a climb. (And don’t forget the phugoid as it seeks the new equilibrium.)This gives rise to what I was taught 54 years ago by my Naval Aviator father, “Pitch controls airspeed and power controls altitude … mostly.” 😉
BTW, I will be giving my “Killing Sacred Cows” presentation at a forum at OSH on Tuesday at 1pm. It covers AoA, lift, acceleration, and why those old wives tales that keep getting passed from instructor to student don’t help. This is part of it.
See you guys at OSH!
Speaking of “old wives tales” something you might want to bring up at Osh is the controversy between the FAA and some pretty bright physics folks concerning the existence or nonexistence of centrifugal force opposing the horizontal component of the lift vector on an aircraft in turns.
The FAA absolutely refuses to consider the nonexistence side of the equation favoring the existence of centrifugal force in all their visual presentations of the forces present in a turning aircraft. NASA on the other hand presents the horizontal component of the split vectors as “unopposed” while instructors like Rich Stowell and John T Lowry go as far as stating centrifugal force is not present at all in the forces acting on a turning aircraft.
Personally I’d like to see some more serious discussion on this issue as it concerns the very basics of what we teach student pilots about aerodynamics.
There should be NO question concerning this issue. It’s literally SCREAMING to be solved so that there exists NO ambiguity at all concerning the answer.
Dudley Henriques
My favorite reply to questions of this nature is the revelation that qualified academics still cannot even explain how lift works: https://www.scientificamerican.com/article/no-one-can-explain-why-planes-stay-in-the-air/ We are really “pushing the envelope” to exclude a mere vector like centrifugal force! 😎👍 Fortunately, I am just a lowly pilot; “trust the force!?”
I do not agree with your assessment of AC 61-50A. For example, in the Steady Level Flight paragraph, it does say “ANGLE OF ATTACK IS THE PRIMARY CONTROL OF AIRSPEED IN STEADY FLIGHT”. But the context of the paragraph is keeping level flight at a particular angle of attack which is not something you do too often in a small airplane, but for long-range planning in a jet, I believe staying at a certain angle of attack is critical. In order to do that, power has to be tweaked to maintain the speed at the steady angle of attack that maintains the lift for level flight. That doesn’t mean power controls altitude. Weight is still opposed by the lift vector. And it is mentioned in another section that if you hold altitude constant (i.e. if you are not at a specific angle of attack), “the amount of power applied will determine airspeed”.
For pilot technique the Airplane Flying Handbook is the appropriate reference. Like always, for level flight, the technique is to use the elevator and adjust the pitch as needed for any deviations in altitude by changing the space between the horizon and reference point on the glareshield (fig 3-8).
I think the Navy vs Air Force methods come down to the need to be at a specific angle of attack when landing on a carrier. I haven’t read or discussed this with anyone – just saying from my own observation. It appears from landings on carriers I’ve seen on videos, the Navy feels it’s critical to establish the landing attitude early because they don’t flare. So to do that I suppose they use an angle of attack indicator and they are holding that landing attitude all along final to be certain that the cable is trapped. And like mentioned in the AC, the power is used to keep the wing flying at the correct speed to maintain the correct lift to maintain the correct line of flight. Does that mean that power controls altitude. If you are in one of the military aircraft where literary the thrust has a greater force than the weight, sure it could. But for all other aircraft, NO. It literally isn’t possible (for example in a Skyhawk, the maximum force from the thrust is 25% of the weight).
Historically, the “Navy Method” is generally understood to be “pitch for airspeed, power for altitude” whereas the “Air Force Method’ is the opposite. (The Navy requires precise AOA and EM to land on tiny pitching “runways”) As stated, both methods work well in certain situations but both also break down in various situations. Aerodynamics for Naval Aviators is the respected “last word” on these issues.
My background in gliders (obviously no power) makes me a historic Navy adherent but as stated I have learned and modified my understanding to a more inclusive way of flying and teaching (esp. with experience in more powerful jets). This historic AC is quite terse but includes the usual “FAA waffling” (make everyone happy approach) trying not to “taking sides” in this argument (I have watched pilots get very loud and red-faced arguing this issue for years). The FAA has largely avoided taking sides in this “control controversy” for years, but certainly “tipped their hand” in this AC. Paragraph 7a. (Flying Technique) makes their position pretty clear (though notice specifying “steady flight”):
1) Angle of Attack is the primary control for airspeed, 2) Power setting is the primary control of altitude. Notice also the mention of “transient speed conditions” in 7c requiring “pitch and power” together (almost new “Chapter 4).
The new AFH “Chapter Four” is a huge improvement providing a more comprehensive analysis of energy management. Hopefully, this analysis inspired some thought and provided some benefit to your safety 🙏
No matter which technique you use on the controls, the external forces are the external forces. The only way to oppose weight is with the lift vector. I was flying with a Part-135 applicant who got low on an approach – he increased power. I noticed the pitch didn’t change. The only thing that happened is we gained 10 knots. We stayed red-over-red. He was left scratching his head later not understanding why the increased power didn’t increase the altitude. When have you seen a breakdown when the pilot was pitching to altitude/power for speed?
” But the context of the paragraph is keeping level flight at a particular angle of attack which is not something you do too often in a small airplane…”
Actually, it is something we do in “small” aircraft all the time. The elevator controls AoA so elevator trim sets the “hands off” AoA for the aircraft. All our “small” airplanes work this way. Unless the pilot attempts to override the trimmed position of the elevator, the aircraft will continue to seek that AoA. (This assumes that the aircraft is stable, something that is pretty much guaranteed.)
Once the AoA is set with trim, any change in thrust (engine power) will result in an airspeed trend, either down or up. As soon as the airspeed departs from the equilibrium airspeed set by the AoA, lift changes. If you decrease power, speed decreases, lift decreases, and the aircraft begins accelerating toward the ground (gravity), so it pitches down. The aircraft will pass through the equilibrium airspeed for the set AoA and the lift will then increase above the equilibrium force and the aircraft will begin to accelerate upward. The result will be a damped phugoid unless the pilot manually damps the oscillation. Regardless, the aircraft will settle on a new, descending flight path at approximately the same airspeed. This is the source of “power controls altitude”. It is all driven by trim selecting AoA.
Now, let’s approach this problem using energy. The aircraft is a system of energy flow. (Energy can not be created or destroyed, only moved from place to place.) if the aircraft is in level flight at a constant airspeed, it is in energy equilibrium. The engine is adding energy to the aircraft at exactly the same rate that drag is removing energy from the system so neither potential energy (altitude) or kinetic energy (speed) change. If we decrease power then energy is leaving the system more rapidly than it is entering the system. We then have two choices: we can allow kinetic energy (1/2 m V^2) to decrease or we can allow potential energy to decrease. In the first case, since mass doesn’t change, velocity much change. The aircraft slows down. We can’t sustain that very long plus that requires a constant change in AoA to maintain level flight. The pilot must apply increasing back pressure or trim to maintain an increased AoA (nose up). Eventually the aircraft will reach a lower speed where the energy leaving the aircraft (drag) equals the energy entering (power) and the aircraft settles on a new airspeed. Look Ma! Power controls airspeed! If the energy input is too low, the aircraft will decelerate until it stalls. The limiting factor is critical AoA. At some point you have to add more kinetic energy, either from the engine, or by converting potential energy. (This is the origin of trading airspeed for altitude or altitude for airspeed.)
Let’s look at the other choice: using energy of position (potential energy — altitude) to make up energy being lost. In that case we don’t change the trim or pull/push on the stick. Now as the kinetic energy begins to decrease, lift decreases, the aircraft accelerates toward the ground until coming back into equilibrium for all the forces. The engine is not producing enough energy to sustain the kinetic energy so the system begins converting potential energy (altitude) into kinetic energy (speed) to maintain the lift/gravity/thrust/drag equilibrium. The aircraft descends at at a rate determined by power. Look Ma! Power controls altitude!
The key thing to remember here is that the pilot decides what will happen by how the pilot controls the AoA of the aircraft using the AoA control (elevator). By allowing AoA to remain as trimmed, power controls altitude and airspeed remains constant. By changing AoA power controls airspeed and AoA is used to adjust lift to maintain the lift/gravity equilibrium, i.e. power controls airspeed.
So here I have approached the problem from the point of view of balanced forces AND from the point of view of energy state. Both produce the same result. That supports both models.
So, welcome to my “Killing Sacred Cows” presentation. I re-explain a lot of old wives tales and misunderstandings using the tools I have begun to describe here. I will be talking about this at OSH in my forum on Tuesday at 1pm. I hope to see you there.
I agree with all you say, but normally the dots don’t get connected. First, the term Region of Reversed Command or Back Side of the Power Curve is misinterpreted. People actually believe that below L/D Max, the power alone will control altitude. I.e. the force to fully oppose weight comes just from the engine/propeller. What’s really happening is that the propeller slipstream becomes the pitch control and controls the angle of attack in place of the elevator as you explained. I include the C172 emergency procedure for Landing Without Elevator Control with students before solo in case there is an emergency of that type and it’s quite a challenge because to simulate the emergency realistically, we don’t apply any forward/back pressure on the control wheel – the transition to approach speed and configuration has to be done only with throttle and trim, and then the approach descent only with power. Everyone gets a really good understanding of how limited and imprecise it is to control the pitch with a cushion of air on an approach where accurate and many times quick changes are required. So I see a connection to the misinterpretation of the term Region of Reversed Command and AC61-50A. The dots don’t get connected – power alone does not and never can control altitude (unless you are flying a V22 Osprey).
The low altitude problem with the Part-135 applicant I mention to David occurred in a Cherokee Six. A heavier engine, shorter arm to the tail surfaces, and/or lack of trim may have contributed to the problem which needed to be corrected with back pressure. But it was an example of someone coming from light single-engine airplanes apparently believing the engine alone controls altitude on approaches. So I agree with what you say, but I’d say it’s primarily limited to light single engine airplanes. And it’s not going to transfer to multi-engine aircraft. So I think it is a great disservice to teach that method.
Centrifugal force? Lift? I have found what works best is to explain to my students that It’s all just different flavors of magic, kind of like the magic smoke inside wires and electronic components that, if it gets out, causes the device to stop working. (And I am an electrical engineer!) 😉
Just because the FAA suffers from institutional pyloric myopia doesn’t mean we have to embrace their dogma. I can explain why there is no centrifugal force but does it matter? I am more concerned about the concept that it is a horizontal component of lift that causes an airplane to turn when ANY change in direction is a turn. A loop is a turn and there is NO horizontal anything in that turn. (Yup, you mentioned one of the sacred cows I am planning to BBQ in my forum.)
As for lift, I do believe I can explain and model it based on the mass, energy, and mean free path of the gas molecules, and how they interact with the surface of the airfoil through elastic and inelastic collisions, but, for our purposes, trotting out the lift formula and explaining that lift and drag vary by airfoil area, mass airflow (CAS), AoA, and some magic hand-wavy stuff based on airfoil cross section, answers the real-world questions about how our airplanes fly. Mostly pilots are looking for a consistent and understandable model for what the airplane will do when we push and pull on various knobs and levers.
I come from that same school; “gravity works,” I don’t have to analyze too deep to confront that challenge…
Keep in mind that I am in no way postulating that we teach physics to student pilots.
I am simply noting that there seems to be conflict between the FAA and other reliable sources on the presentation in official manuals on an issue concerning basic aerodynamics. This situation should not exist in the training community.
It deserves a closer look that’s all.
Let me be perfectly clear concerning the issue or non-issue of centrifugal force in turns. I’m not taking a side nor am I seeking a correct answer. I know the correct answer.
I am also NOT suggesting we teach physics to our student pilots.
I AM saying that there seems to be conflict between the FAA and knowledgeable people in the physics community on the way aircraft turn forces are depicted in FAA manuals. I’m not questioning either community as to the accuracy of their positions.
I AM suggesting however that the existence of such a conflict of opinion openly viewable to our student population is NOT in the best interest of proper flight training.
I simply believe that a solution to this conflict of opinion is for the FAA to perhaps become more aware of said conflict and possibly consider a simple alteration of their presentation diagrams and text in the manuals that reflects a better “picture”, that doing this will serve the training community in a more positive manner.
It’s not good nor does it serve the interest of flight safety to have experts in our physics and aerodynamics communities in conflict with the FAA on issues basic to aerodynamics.
If a few additional words in the FAA manuals will present a better and more accurate picture for the training community I simply believe this should be considered.
It is with this in mind…….and ONLY this……that I have mentioned these issues here. Perhaps if the word is spread some good can be accomplished.
Warren: Yes, at higher speeds a change in power/thrust is going to create more change in speed than a change in lift, certainly initially. Also, at higher speeds a smaller change in AoA will result in a larger change in lift … in the short term. Regardless, if you really and truly want to change steady-state climb/descent, it requires a change of power and an aircraft that is both statically and dynamically stable will tend to continue to seek its trimmed AoA. So, long term, “power to altitude and pitch to airspeed,” works.
The point that David made is that there is interaction and we need to 1) understand what we are changing, and 2) what will be the resulting effect on the airplane. “Pitch to airspeed and power to climb,” and, “Power to airspeed and pitch to climb,” are both too simplistic and slavish adherence to either will result in poor aircraft control.
A perfect example of how we need to explain control interaction is the power-to-climb demo. It starts hands off with the aircraft trimmed for something close to Vy/Vg, i.e. best L/D. I add power and the nose pitches up and the aircraft begins to climb. I reduce power to idle and the nose pitches down. But I also show that a rapid change in power will result is a rather remarkable phugoid. I then point out that we can’t completely separate AoA control from power control. We need to “help” the airplane quickly achieve the new steady state with judicious use of the other control, the AoA control (elevator) in this case. So a big change in power requires substantial input to prevent the phugoid from developing. That results in smooth control. Students “get” that really quickly.
In fact, this is the main focus of lessons 1 and 2 for my primary students. Once they understand this relationship and interaction, they are ready to go on to precision control of altitude, airspeed, and heading. Pushing on to anything further before this is learned just frustrates the student because they can’t get the airplane to do what they are asked to make it do.
Dudley: yes, it would be nice for the FAA to get it right in their publications. However, last time I checked, they weren’t listening to me. My students do listen to me so I just have to press ahead and teach them what is correct and point out the areas in the FAA pubs that are not accurate. That is the best I, and probably you, can do.
I agree with you. In the end it’s up to instructors to “tweak” the nuances the FAA drops in our laps.
My only reason for opening this discussion is to have a dialog ongoing in our CFI community that just “might” poke the right person in the FAA to at least take a fresh look at issues like this one.
After all……we DID get rid of the equal transit theory……………just perhaps we can stir the pot again and get something of value done for the training community.
No harm in trying !
You are right Dudley, keep pushing improvements. There has been good improvement in all the handbooks over time. SAFE members contributed most of the content in the last two AFH editions and the Chapter 4 (Juan Merkt, ERAU) was a huge step forward.
While a start, the new chapter in the AFH devolves into the usual trap of a designer-oriented approach to training. As pointed out by Langewiesche, “What is wrong with ‘Theory of Flight,’ from the pilot’s point of view, is not that it is theory. What’s wrong is that it is the theory of the wrong thing—it usually becomes a theory of building the airplane rather than of flying it.”
A first principle of flying light airplanes is “Pitch + Power = Performance.” This succinct statement points to energy management. But it is so much more than that. Substitute AOA for Pitch; thus, “AOA + Power = Performance.” Airspeed (V) and G-load (G) are proxies for AOA. Hence, “V + G + P = Performance.”
This simple statement takes us to the two types of airplane performance we care about: Climb Performance and Maneuvering Performance. The V-P diagram illustrates climb performance. In this context, “climb” can be positive (climbing), zero (level), or negative (descending). We can talk about energy; which axis is controlled with throttle; which axis, with elevator; what happens on the back side, the front side, and way on the front side. We can include excess power (Pxs = Pav – Pre), which translates into rate of climb (ROC).
We can overlay and discuss critical V-speeds such as Vm, Vs, Vh, and Vne (vertical lines drawn on the diagram); Ve and Vy (horizontal lines); and Vx and Vbg/Vbr (tangent lines). We can discuss the effects of things such as airplane configuration, density altitude, and bank angle.
We can map out a go-around. Say, for example, we add go-around power while at 60 knots. Achieving max ROC is important in this example, which is a touch over 70 knots. Pushing the elevator control FORWARD allows us to climb at a faster rate – counterintuitive (just like stall recovery) unless we understand the P-V relationship. Similarly, there are speeds on either side of Vy that, with go-around power applied, result in the same ROC albeit less than max ROC. In one instance, we would have to push to climb at a faster rate; in the other, pull to climb at a faster rate. Again counterintuitive, but normal in terms of the P-V relationship. We can correlate key speeds like Vy with their corresponding pitch attitudes, too, should we ever lose our airspeed indicator.
We can even map out and discuss a complete engine failure (P = 0), in which case the P-V diagram flips and becomes a Rate of Descent vs. Speed diagram (ROD-V). Correlate the glide attitude with your best glide speed here, too.
The V-G diagram, on the other hand, illustrates maneuvering performance within the confines of the airplane’s aerodynamic and structural limits. The same Vne line from P-V transfers to V-G. The same Vs line transfers as well, but the V-G diagram shows us all the stall speeds from zero G to the design limit G.
Whatever we say about the V-P diagram must be consistent with, and transferrable to, the V-G diagram and vice versa. Does anyone think we can substitute power settings along the V-axis on the V-G diagram, making it a P-G diagram?
When they happen to be discussed, V-P and V-G are presented as totally unrelated pictures. The reality is that three parameters tell us what the airplane is doing at any point in flight: V, G, and P.
Since V-P and V-G diagrams share the same speed axis, imagine connecting the two diagrams at right angles to each other along the V-axis. Imagine an airplane in flight in the space between the two diagrams. Projecting the airplane’s shadow onto the V-P diagram informs us about its climb performance at that moment. Likewise, projecting the airplane’s shadow onto the V-G diagram tells us how it is maneuvering at that moment. I’ve put a graphic on my website illustrating this for level flight at 1G: https://www.richstowell.com/v-p-g-diagram/
The interplay between pitch and power on performance should be clear, as should the primary use of elevator and throttle controls. Also note that pitch-for-AOA/speed and power-for-altitude are assigned during the most critical of flight operations:
The mountain, canyon, and backcountry flight environments (see Amy Hoover, Lori MacNichol, et al.)
The technical logic of airplane performance (“Performance of Light Aircraft,” John Lowry)
AOPA articles (“Fatal Instinct” and “Power and Pitch,” Barry Schiff)
The flippers and the throttle (“Stick and Rudder,” Wolfgang Langewiesche)
Fundamentals of flying technique (FAA)
Fundamentals of stall recovery (FAA)
Go-around/Rejected Landing (FAA)
Also note that airplane manufacturers assign pitch-for-AOA/speed and power-for-altitude during critical flight operations and emergencies in their airplanes. For example, see the amplified procedures in the Cessna 172P:
Short field landing
Landing without elevator control
Glassy water landing (floatplane version)
Engine failure
Emergency descent through clouds
Recovery from a spiral dive (in clouds)
I teach pitch and power thus:
PITCH
The elevator control moves fore and aft. The airplane’s response is seen as head-to-feet movement by the pilot. Primary effect is on AOA, which presents as changes in at least a couple of these: V, G, attitude, flight path. Possible secondary effects might include changes in rigging and engine effects, precession, angle of bank, and altitude.
POWER
The throttle moves fore and aft. Primary effect is to move the airplane from here to there (taxi from here to there on the airport; fly from airport A to airport B; climb or descend from one altitude to another). Possible secondary effects might include changes in torque, p-factor, slipstream, and airspeed.
Do we inadvertently, negatively reinforce “use the secondary effect of pitch for altitude” as the norm, which by default makes all the above scenarios the exceptions? Or is “using the secondary effect of pitch for altitude” really the exception, especially since we must be in just the right slice of the envelope, close to the correct glideslope already, and with a certain amount of speed we don’t need or care about for the desired effect? How do we push learning to the correlation level for the entire performance envelope?
My motto: “Pitch for the speed you need.”
Wow, something tells me you have thought a lot about this Rich. As always, you provide us all a lot to think about (a semester’s worth?) Thanks for the input…and anyone not familiar, please see Rich’s free course: https://www.richstowell.com/learn-to-turn/
BTW: The two (excellent) Barry Schiff articles are in the SAFE library: Fatal Instinct and Pitch and Power
Why does the auto-pilot (and the pilot) in an airliner, which costs millions of dollars and carries hundreds of passengers, pitch to altitude, not airspeed.
You actually can slave the autopilot to either alt. or airspeed – FLCH (usually ATC wants alt. but sometimes specifies *both*)
Warren: So you pull back on the stick to increase the AoA, which increases lift. The aircraft begins accelerating along the lift vector. It does start climbing. However, if you don’t follow up immediately with power, kinetic energy (speed) is going to convert to potential energy (altitude) and the aircraft will slow down and rate of climb will shortly drop back accordingly. That is the “zoom climb”.
Don’t take my word for it. Go try it for yourself. Ask the question and then let the airplane answer your question for you. It doesn’t matter what airplane you do it in, the result will be the same.
Hi Warren. The laws of aerodynamics don’t care about the cost of the aircraft. Airline flying occurs in a small part of the potential flight envelope, especially during approaches where the airliner is in that slice of the envelope where the approximation — precisely flown though it may be — works out. Note, however, that for all the money and automation put into airliners, the first action taken to recover from an upset is to disengage the autopilot and autothrottles. The pilot then must use stick and rudder skills to apply the appropriate recovery response.
I don’t think anyone has intimated that speed cannot be traded for altitude, provided the conditions are right. The overarching principle, however, is revealed and better understood using a V-P diagram. Draw it up, put a dot representing the airplane’s current energy state, and make the case for how the energy state can be changed to another point on the diagram. And it has to be consistent with what’s happening on the V-G diagram as well.
“My motto: “Pitch for the speed you need.” That leaves horizontal forces (thrust) to control altitude. I don’t think that works too well.
I’ve just pivoted at the top of a Hammerhead in my Extra 300. I need 160 mph for the next maneuver. Option 1: Keep pitching the nose straight down and leave the throttle open. Option 2: Keep pitching the nose straight down and close the throttle. By adjusting my timing on the down line, I can return to level flight at 160 mph either way. Option 1 will burn more fuel, but less altitude. Option 2 will burn more altitude, but less fuel. I’ll choose Option 1 if altitude is at a premium; if it is not, I can draw a longer, more impressive down line with Option 2. Either way, I’m pitching for the speed I need.
I’m loafing along in level flight. I now need to fly as fast as I can in level flight. I’ll pitch to Vh while simultaneously coordinating power to maintain level flight. I now need to fly as fast as I can. I will pitch even more to accelerate as close to Vne as I dare. Depending on the airplane, I might even have to reduce power as I pitch for ever more speed.
My engine just quit. I set the pitch attitude for the speed I need: best glide.
I’m on the short crosswind in the Decathlon at Santa Paula. I descend at 85 mph with the power near idle. I want to be at 75 mph as I hit pattern altitude. I also know the airplane requires 15 inches of manifold pressure to maintain TPA. I change the pitch attitude from the descent at 85 to the level slow flight pitch attitude for 75 as I increase power to stop descending in time to hold TPA. I’m surely not adding power to slow down!
I have a floating elevator. On approach, I trim for the appropriate speed and use power to control the rate of descent.
Rich July 4, 2022 at 7:47 pm comment. A Reply button did not come out on your comment .
I haven’t done a Hammerhead in a long time but they sure were fun.
“I change the pitch attitude from the descent at 85 to the level slow flight pitch attitude for 75 as I increase power to stop descending in time to hold TPA.” You are increasing power nearing TPA which will try to accelerate the airplane. To avoid an increase in speed, you have to increase pitch to hold 75. That increase in pitch increases the lift vector and is what holds the altitude, not the increase in power. That gets lost with a lot of pilots, like the Part 135 applicant I mentioned, who tried to correct a low approach with power alone. I think CFI’s have to be careful to not omit that point.
Your approach is similar to the approach in the C172 manual for Inoperative Elevator – trimmed to a certain speed and using power to control altitude, which I’ve done many times with my students. However this approach is quite limited. It manipulates the pitch with a cushion of air (propeller slipstream) – in rough weather, that will not provide adequate pitch control. It also presents a problem when the winds are gusting because the pilot will probably chase the airspeed with the elevator and destabilize the approach.
Rich – July 4, 2022 at 7:47pm comment.
Sorry I left out a point. All of this time in the traffic pattern, you are initially adjusting power when there is an altitude deviation then second adjusting pitch if the airplane accelerates or decelerates. That means your lift vector correction, which is what really controls the altitude, is delayed. Initially adjusting the pitch (lift vector) for any altitude deviations (and simultaneously power for speed if necessary) will keep your altitude and glideslope more accurate. In good weather conditions it isn’t a big deal but in rough weather it is.
After we level and set power, any sane pilot is actually “pitching to altitude,” no question, speed sorts itself out based on desired power setting. A pilot would drive themselves nuts leveling with small power changes to control deviations. Obviously, any significant climb or descent requires a combination of both for smooth control (total energy management). Debating which control is primary while in the center of the envelope is not especially useful and can be confusing for students (and the primary reason I modified my approach).
I personally “pitch to A/S” to achieve optimal performance in climbs/descents, but then pitch to level. When accelerating level are we pitching to altitude or airspeed? And does it matter here? A combination of pitch and power = performance. Where trouble arrives from confusion is low/slow (critical phases of flight) and pilots try to “pull to get altitude.” This is such a natural human reaction (built into our DNA) but physics just does not work that way.
Warren;
Actually it works quite well.
Ah, Rich, are you are always several steps ahead of me. Thank you for that very succinct treatise. You’d think that I would read all your stuff first rather than recreate it in my own head first. As Tom Lehrer put it so succinctly:
Plagiarize
Let no one else’s work evade your eyes
Remember why the good Lord made your eyes
So don’t shade your eyes
But plagiarize, plagiarize, plagiarize
Only be sure always to call it please ‘research’.
Thank you again.
“You actually can slave the autopilot to either alt. or airspeed – FLCH (usually ATC wants alt. but sometimes specifies *both*)”
I should have said on approaches. Do you have a choice then and if so how do pilots decide?
In “approach mode” every autopilot must follow the X/Y guidance and servos drive air-controls to achieve this. Pitch to glide slope, control speed w/pwr works great here. But the same dogmatically-applied paradigm regularly kills pilots on go-arounds trying to “pull the airplane” over the trees (often must lower the nose to achieve Vx climb – very counter-intuitive) Soft-field T/O (same – airborne < stall spd., lower the nose for climb airspeed). Any rote formula has a failure mode. Since power is limited, and occasionally fails, pitch for A/S is universally dependable as fall back. In every case total EM (correlate all forces) is smoother/safer.
Believe me I hear you about the go-around hazards. But I don’t think it is the same dogma at all. The POI at my FSDO long ago gave me a simple guideline for pitch and power. When power is variable, pitch to altitude. When power is fixed, pitch to airspeed. So applied to the approach, when power is variable, pitch to altitude (glideslope). On the go-around at full power, power is fixed, so pitch to airspeed. Two different worlds.
But isn’t that confusing, with greater potential for error?Physics is not changeable (also why I hate “region of reversed command!”) There is no time for mental gymnastics in surprise situations (one time this way next time reverse).
A couple of more points. On the go-around, I think the Airplane Flying Handbook and the POH are all in sync with the guideline from the POI. Basically it’s just another climb maneuver in a small airplane always at full power pitching to airspeed.
On the approach you say pitching to glideslope works well. That’s been my position all along but it seems you and others were saying otherwise or saying the FAA says otherwise which I don’t think is the case at all.
In heavy aircraft with engine spool-up time and mass, you definitely pitch to the glide slope, but we are stabilized in the center of the performance envelope and got there by setting both pitch and power to achieve performance (not chasing rote rules).
This Ed Kolano article is very well written and helped my understanding – sorry no diagrams.
“But isn’t that confusing, with greater potential for error?Physics is not changeable (also why I hate “region of reversed command!”) There is no time for mental gymnastics in surprise situations (one time this way next time reverse).”
It has never ever been a problem. In small airplanes, climbs are always full power/pitch to airspeed. Vx, Vy, go-around. Have instructed since 1980 and have never seen any problem with this transition. I also apply and reinforce this is slow flight, even flying below the white arc. I do all four fundamentals flying below the white arc. When we do the climb, it’s full power/pitch for airspeed (below the white arc). If conditions are reasonable the airplane will climb.
David July 4, 2022 at 7:20pm comment
The Ed Kolano article was quite an interesting read – thanks. What an analysis he did – considered every aspect and technique. And came to the right conclusion after in-flight analysis – pitch for glideslope and power for speed, which was highly supported by his CFI and DPE, and is the recommended technique in the Instrument Flying Handbook (pg 9-40). Works in all aircraft I have flown and in all conditions and of course if it’s the best technique for the ILS it’s best for visual approaches also.
David – your July 4, 2022 at 6:12pm comment.
“But isn’t that confusing, with greater potential for error?Physics is not changeable (also why I hate “region of reversed command!”) There is no time for mental gymnastics in surprise situations (one time this way next time reverse).”
Not confusing. It’s the same as all takeoffs – full power / pitch to airspeed so it is well within the natural instincts for all pilots when performing the initial climb. I’ve never seen anyone have a problem with changing from ‘pitch to aiming point’ on approach to ‘pitch to airspeed’ on a go-around. The biggest challenge is resisting the nose-up trim as that is for all pilots.
On the other hand, this brings up yet another reason why pitching to airspeed on approaches is problematic. In the descent to the flare, the pilot is pitching to airspeed, so the left-hand/eye coordination is focusing on the airspeed, watching for airspeed deviations and making elevator corrections. Beginning the flare, the objective is to bring the airplane from 10-20 above the surface down to the surface for a gentle landing. Now at the most critical moment of the flight, the left-hand/eye coordination has to make a critical switch and make elevator inputs that control the rate of descent and altitude of the airplane. I think that is a far greater disadvantage to have to suddenly ‘switch gears’ like that moments before the landing than the switch made on go-arounds, which is just conforming to normal technique for all initial climbs.
I would hope any properly trained pilot flying down final would stabilize both pitch and power with *primary* attention to airspeed. Any pilot referring inside to *either* the altimeter or airspeed when leveling off and flaring to land was taught wrong and going to have problems (sounds like my Cornell Engineers – can’t get them off the gauges)! If I glanced anywhere inside on short final it would be at airspeed. Kinetic energy is exponential whereas altitude is linear (and I can see it out the window obviously).
I was referring technically only to what is done with the elevator and what I think is a problem (pitching to airspeed/power for altitude and then close to the ground pitch to altitude/power for airspeed). If you control the airplane like your autopilot does, that potentially dangerous change doesn’t have to be made. The elevator controls the altitude on the approach, roundout, and landing. The power controls the speed at all times.
Really I don’t see how either pitch or power could be considered primary. For example, on an approach to a short runway which will require passing close to an obstacle (good example St Barts), is airspeed primary to control landing distance or is pitch primary to avoid a collision with that hill? They’re both primary. There’s near zero tolerance for error for either. The total energy diagram implies there’s one correction needed in each sector. Airplanes don’t work that way. I think it’s misleading.
https://i0.wp.com/safeblog.org/wp-content/uploads/2022/07/EnergyManagementBlogRevisited.png ??
This was from a recent Bold Method article: https://www.boldmethod.com/learn-to-fly/navigation/how-to-control-pitch-and-power-on-a-glideslope-to-landing
Warren: Not sure why the Reply button was missing on my previous response (don’t think I have control over that). V-P and V-G diagrams speak for themselves. No need to get into the weeds with all the force vector rigamarole. Besides, power has to do with thrust and drag, not lift.
I’ll reiterate: as long as the pilot is in the right slice of the envelope, near the intended target altitude profile, and close to where the energy state needs to be, the approximation “pitch for altitude” will have the intended result (e.g., Kolano’s article). And by “approximation” I mean making use of one of the possible secondary effects of pitch control. Normally we cancel unwanted secondary effects, but sometimes we take advantage of them. A slow roll in the Decathlon is a good example: apply left aileron and allow adverse yaw to raise the nose up and to the right to form the “sacred circle” of the slow roll before augmenting with right rudder.
I’ll also reiterate: we need to teach according to first principles that push learning to the correlation level. Here, that means using V-P and V-G diagrams. Draw them up and talk about operating throughout the entire envelope, how they apply to emergencies and potential gotchas, and so on. Whatever we say has to be reconcilable against those diagrams. V-P easily explains my level off at TPA while simultaneously slowing from 85 to 75 vs. your convoluted counter explanation. The diagram also easily illustrates the proper response to the low-and-slow approach for your 135 applicant: push the throttle and the elevator forward.
This is a good discussion. However I think it useful to rewind just a bit and point out that the laws of physics dominate the answer. We can talk about it any way we want but energy management has to dominate the discussion because … Physics.
A quote, often attributed to Albert Einstein applies here, “Things should be made as simple as possible, but no simpler.” We can talk about how it is easier/harder for the student to learn but the bottom line is, they student must learn the behavior of the aircraft to AoA and power changes in order to be able to safely operate the airplane. I think that, as CFIs, we have a tendency to try to simplify things by giving students wrote procedures to execute that will get them early success and have them apparently progressing rapidly. This might not be a good thing. Developing a full understanding and execution of the basic stick-and-power skills (as opposed to stick-and-rudder) before moving on will cement proper behavior going forward. (Several platitudes come to mind here.)
I do have a good recent example. I have a student who already had his PPSEL but had not flown for many years while building an RV6A. When we started flying it was apparent that his response to being low on the approach path, or responding to the uprush of a steep descent, was to instinctively pull back on the stick. One of the characteristics of our local airport, sink on short final caused by the wind over a hill adjacent to the approach path, would trigger this response nearly every time. It took me 35 hours of dual instruction to finally break him of the habit and get him to correct a low-energy situation though the application of power (in addition to the increase in AoA). How much better would it have been if he had learned that from the beginning and not have to unlearn the dangerous behavior and then learn a new behavior to replace it?
In the end, arguing about the correctness of, “pitch to altitude,” vs., “pitch to airspeed,” is non-productive. Make it as simple as possible BUT NO SIMPLER. Teach it correctly and then cement the understanding through exercises and repetition. Controls interact. You cannot change one without awareness of what changes on the other. This needs to be the first lesson learned as EVERYTHING is built upon that going forward. Teach it, build in repetition, and cement that learning so it become unconscious competence.
Hi Brian. Agree 100% on the inter-relationship of pitch and power and is the reason that I still include training in slow flight BELOW the white arc. If we sink below the target altitude, we need more lift to regain the target altitude. However, if we only apply back pressure, a loss of 1 knot may result in a stall. Power must be first applied (at that speed it’s usually full power) so that even the minimal amount of back pressure can be applied and when the back pressure is applied, carefully monitor the airspeed to avoid a stall (at that moment the airplane is at fixed power so pitch to airspeed). This method (apply power then pitch) is straight out of the Airplane Flying Handbook now Chapter 9 for how to react when approaches are low and slow – it’s been there as long as I can remember. I like to take it to the maximum degree at a safe altitude to develop the best possible technique and feel for the controls.
On approaches, the pilot has options on this coordination which will depend on the airplane’s speed. For example, on an ILS at 90 knots, small deviations from the glideslope will usually only cost 2 to 3 knots (maybe 5, which should be the max allowed) when pitch is adjusted. There’s really no need to adjust power – you gain or lose a couple of knots and you’re miles from stall speed. On visual approach at 65 knots (middle of the recommended range for C172), a couple of knots one way or the other in good conditions is still no problem, but the pilot should have a personal minimum speed. If that happens to be 65, then by all means coordinate the back pressure with additional power and don’t get below 65.
I flew at Hartford-Brainard many years. There’s a berm around much of the airport holding back the Connecticut river which created really interesting approaches. Nearing the river, we would encounter a downdraft. As we crossed the top of the berm, we would be hit with an updraft. After getting through that and continuing to the displaced threshold, there would be no updrafts or downdrafts.
So many approaches were an increase in both pitch and power for the downdraft, a decrease in both for the updraft, then return to near where both were in the earlier part of the approach. I always thought that airport was one of the best training grounds in the country.
Reading this thread with some interest,
What I have instilled into every instructor I’ve ever trained is this;
Concerning the pitch vs power issue;
The issue isn’t pitch and it isn’t power. It’s more basic than this. The OVERALL issue lies deep within the training mindset and peripherally within the thinking of those who believe that flying an airplane is a matter of “when this happens………do this”.
This has been the thinking of the people who control our training material for as long as I can remember. You can see it in the current ACS where the FAA apparently believes that crossing every T and dotting every i is what is needed to produce a good pilot.
I for one have never believed this.
Because flying occurs in a constantly changing 3 dimensional environment where no two flights are ever exactly the same, pilots conversely should be trained to both think and perform in this environment.
What good can possibly come from training that directs a pilot to perform a specific act when a specific thing happens when the peripherals involved when that specific thing occurs will differ every time it happens. The wind for just one example will never be exactly the same when an action is required by a pilot on the controls of the airplane being flown. The exact response required will
never be the same………NEVER !
The pitch/power issue is a prime example of how something “written in stone” is not enough when it comes to training.
Pitch for airspeed and power for altitude might work just fine in a light airplane, and even there a better understanding is required for a pilot to REALLY comprehend the issue. Pilots should NEVER be taught to think of pitch and power as SEPARATE, each to be used alone as solving a specific problem on an approach. Pilots should be trained to think on a much higher level than this.
Pitch vs power occurs not in a single event scenario but rather in a multiple event scenario. In other words when you affect one you affect the other. Pilots need a thorough understanding of how these two factors interact to be safe. Pilots also need to understand that not all aircraft require identical handling on approach. For example the power/pitch standard might work one way for a Cessna 172 and quite another when on approach in a T38. Basic concepts can change as aircraft increase in performance.
Basically what all this means is that instructors are well served as are their students by starting at the very beginning to deal with flying an airplane as a FLUID environment.
A good mindset for instructors to impart on their students is that flying an airplane ALWAYS occurs in a constantly changing dynamic environment where nothing is ever exactly the same. What you did last time to correct something might not work exactly the same way this time.
THIS is why good instructors teach well beyond the test !!!!!!!!!!!!!!
Well said Dudley!
I’m with you, Dudley. You rightly allude to the fact that we always need to specify the caveats. For example, “we’re talking about light airplane flying here” vs. military or air transport category flying. Not only are the aircraft notably different, but so too are the standards for the pilots.
I’m also with you regarding your earlier post about the accuracy of FAA content. The issue concerning the need to delve into physics at the expense of more practical content for GA flying aside (do we really need to be reminded about the horizontal component of lift at least 16 times?), if the FAA feels compelled to go there, they should at least do so with accuracy. We’re paying for that content, after all.
Dudley – totally correct. No two approaches are the same. One of the biggest problems we have is standardizing pitch and power settings for descent, like when they say abeam the aiming point, set rpm to xxxx and pitch to xx airspeed. That instantly puts the airplane at the mercy of the conditions. I was just discussing this very topic via email with the Chief Flight Instructor of a major school who had written an article in their latest publication discussing their policy on pre-determined pitch and power settings. Many schools and individual CFI’s do this and then continue pitching to airspeed for the approach, another big problem in my opinion.
Warren; I’ve never been a fan of “predetermined ANYTHING” when it comes to teaching a student to fly other than say a checklist. Once in the air flying is totally a fluid situation and students should be taught to fly in this constantly changing environment.
Predetermined pitch and power for me is totally counter intuitive to what a pilot ACTUALLY has to accomplish to set up a proper stabilized approach.
To be more specific, you know where you are. You know where you want to be. You know the tools you have available to accomplish that. You do whatever is necessary to put the airplane there in the condition it has to be when it gets there.
NEVER FORGET…………..”no two flights are ever the same because when flying an airplane you are working in a constantly changing environment”.
Dudley – As far as I can tell, I instruct exactly as you do. I’m not sure why you think I would be using a predetermined pitch and power – I don’t. The short-field approach would be the same as a normal approach in this sense: the pitch would be adjusted ‘as needed’ to keep the airplane on the desired line of flight to the aiming point – the power would be adjusted ‘as needed’ to maintain desired speed, with gust factor added at the pilot’s discretion. That means, as you say and I agree 100%, that the pitch and power combination is never the same because the conditions are never the same.
I was referring to the chief instructor at a major school in your post who wrote an article on predetermined settings. I took it that he taught predetermined settings and was just commenting on that thought.
Gotcha. I saw your comment right after I commented on short-field approaches and something had blocked some of the comments on my computer, so I connected your comment to the wrong place. I just realized the url for my original bookmark isn’t correct – haven’t had that happen before but probably is the reason I also wasn’t getting reply buttons.
Warren and Dudley: what is wrong with knowing some values of pitch, power, and configuration that will yield a particular performance from the aircraft? I start teaching that to my primary students from day 2. In fact, I teach them how to FIND those “presets” by experimenting with power settings and pitch values in order to achieve the speeds and climb/descent rates they expect to be using.
I know that if I am going to fly an ILS and know that I want to maintain a particular IAS it sure helps if I have ballpark numbers for pitch, configuration, and power setting. Sure I know that I will need to tweak the values. If I am trending below the GS because I have a greater than expected headwind, I know to add a touch of power to reduce my descent rate.
Perhaps I am misunderstanding what you are saying. Please enlighten me.
I do teach standard “pitch/power targets” (this was essential when I ran a school w/ many instructors) *BUT* it was clearly understood these were starting points (not absolutes).
I often compared this to a recipe with set measures and ingredients; it always is going to vary a little depending on circumstances!
This is what I told that 141 Chief Flight Instructor – In the long run, it concerns me what standardized pitch and power settings could do. During the student pilot period of flying, things are closely controlled. Weather is good, runways are familiar. The standardized settings keep things within a reasonable box. But that may result in some skills not getting fully developed – the identification of the aiming point – the estimation of the airplane’s trajectory – the coordination of controls. I think those things were probably a factor in one of the most unexpected accidents about which I have ever read. A couple of guys were making an approach to Catalina Island, CA, undershot the runway and crashed into the vertical ground short of and below the runway. How in the world could that have happened? I suspect rote standardized procedures and of course lack of other necessary skills.
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93023/pdf
Absolutely nothing wrong with that…….as long as a pilot knows and accepts that any “constant” used is totally flexible and subject to change via conditions,
All I’m saying is that pilots should be taught flexibility as opposed to a more inflexible approach. There is nothing at all wrong with shooting for a “target”, but one achieving that target a pilot should be trained and ready to “adapt” immediately to a changing condition.
That’s all.
My mentor (WWII guy) never provided any parameters; total “discovery method!” That is inefficient.
Very basically, when I get established at the correct angle to the aiming point, I’m looking at the runway when I make a substantial reduction in power by sound as I lower the nose to stabilize the aiming point. Next I look at the airspeed and nudge the power to hold the speed (which is just in a reasonable range for base at this point). Then I trim. So in 5-7 seconds, I’m done with the transition to the descent – on glideslope, speed, and hands free. It allows for all variable conditions. I do not look at RPM or VS.
Exactly. Conditions are a little different but knowing those preset values gets you in the ballpark from which you make small changes to achieve the desired values. Not knowing yields a lot of thrashing in the cockpit as one tries to figure them out on-the-fly.
There is a corollary to this which is rather important as well. If you find that a particular pitch+power+config does NOT yield close to the expected performance, you may have some kind of problem with your aircraft.
Exactly; a good point to emphasize (physics again👍)
Somehow, no matter what one does, that pesky physics always seems to creep in.
You can bend the rules……but not the Laws !
I believe the main point to be made about parameters is that it’s fine, even preferred, to have parameters and to seek to use them, but also to recognize that once met and finding conditions unfavorable at those parameters, pilots should be prepared through training to be ready if needed to alter their procedure to meet the new circumstances rather than an insistence from training to seek to maintain parameters that are not optimum under the circumstances.
In other words……….the flexibility of which I speak constantly.
David – “This was from a recent Bold Method article: https://www.boldmethod.com/learn-to-fly/navigation/how-to-control-pitch-and-power-on-a-glideslope-to-landing“.
I am familiar with that boldmethod article and I made several comments on it and I think the majority of the comments went with pitching to glideslope. An Air Force commenter described the use of the controls with the same technique I mentioned was given to me by my POI at the FSDO – when power is fixed (i.e. during climb, go-around, or during engine failure), pitch to airspeed (what we all do). When power is variable (i.e. when the engine is running normally and we can adjust the power as desired/needed), then pitch to altitude (ex: when in cruise, a vertical speed descent, or approach).
This is the way your jet flies. In cruise at 35,000, elevator holds 35,000 (power set for cruise and holds airspeed). When you are on a STAR at 2,000ft and 180kts, elevator holds 2,000ft and a reduced power setting holds 180kts (like in a car). On the ILS, as I believe you said, the auto-pilot pitches to the GS and the throttle holds the airspeed. Is that not all correct. Why is a small airplane any different?
Small airplanes are not different. What IS different is how the autopilot is set up to operate in the narrow slice of the envelope of steady level (or near-level) flight, as well as flight close to the correct approach profile on an ILS. This is where the secondary effects of pitch and power can be taken advantage of.
Also, flying is not like driving a car — best to avoid that analogy.
It’s interesting that the governing physical law illustrated by the V-P diagram (included in the new FAA chapter on Energy Management, and included in other FAA handbooks for decades) seems to be discounted at best, dismissed completely at worst in all this discussion. All claims need to be demonstrable and reconcilable with that diagram.
Yes
Actually, small planes are different in a very important way; capability! (Remember I fly a Champ). An F-35 can “make airspeed with throttle” in any direction (the throttle in a Champ is a “volume control”). Small pistons are very power-limited. We live in the world of energy management (and transfer)!
Have you ever watched the “Flying Farmer” routine in a Cub? This is probably the most elegant (and scary) flying exhibition. There is no “extra power” to recover goofs…every move is careful management of energy (mostly transfer); no “bucket of energy” to save your mistakes!
Good point Rich. I am, for the first time in a long time, teaching a very young primary student. The negative transfer from driving is so very apparent (both 2D -on the ground- and also 3D – confusion with up/down control with “elevator”). From the very beginning, we are emphasizing bigger picture of energy management.
I’ve always used select references to cars to take advantage of the student’s prior experience as recommended in the Instructor’s Handbook. There is a direct relationship in a car starting to go up a hill and needing more power to maintain speed or downhill and requiring less power to maintain speed to when a pilot applies back pressure and has to add power to maintain speed and vice versa.
As far as I know and have seen, the autopilot in a small airplane performs the same basic functions as the autopilot in any other airplane – i.e. slaves the elevator to the glideslope, and every one I have flown keeps the GS needle in the middle. The airspeed range for the autopilot is large – from 70 to 140 kts. Approaches are done usually in about a 20-30 knot range (80-110kts), but enroute climbs and descents at higher speeds, and the control seems to be the same. By the time training is done on approaches, I have included a demonstration of an aircraft carrier approach (not to recommend it but to understand the hazards and to understand aircraft control in a possible emergency), and I include an approach at a speed that would be used say if the airplane were covered in ice, about 100kts. In all of the approaches, autopilot and manual, the pitch (elevator) is controlling the glideslope, the only way I have ever flown the airplane (except for when performing the Landing Without Elevator Control procedure), and the control of the airplane feels the same throughout that large range of speed. Could you expand on your reference to a narrow slice of the envelope? To me, precise control can be achieved at any speed manually or on autopilot.
Don’t everyone chime in at once 😉
David: Excellent point about factoring in capability! In the Champ, J-3 Cub, Stearman, Brian’s Moth, the performance speeds tend to be all bunched up, whereas in a TBM 850 they are much more spread out. Nothing like “one speed does everything” in a Champ or Cub! But as illustrated in the jet example Dudley presented earlier, in some corners of the envelope all that power can do nothing but aggravate the situation.
Related to Brian’s reference to the Air Force putting cadets in gliders. If one were to go into the glider tow business, what would the business model be? In other words, should you charge for the use of the power available in your tow plane by the knot, or by the foot? If the former, glider pilots would love you, but I suspect you’d soon be out of business. If the latter, you might have a shot at making some money.
Re: Brian’s reference about stalls caused by the autopilot pitching for altitude. I did several tests over a couple of flights in a high performance airplane equipped with an autopilot. Set altitude hold with intentionally mismanaged power, twist the heading bug, and consistently encounter an accelerated stall. (I’ll be able to elaborate at a later date.)
Warren: First off, let me say I have enjoyed the conversation here with you and these other extremely intelligent, knowledgeable, and thoughtful instructors. Sometimes I feel very much alone when trying to get these concepts across to people who then look me in the eye and say some variation of, “My CFI said it; I believe it; and that settles it.” This is why I am interested it teaching two groups of people: the brand new student who arrives with no preconceived notions, and the CFI candidate.
That being said, I do believe you need to let go of what appears to be a tendency to seek support for your ideas in the words of so-called authorities. The nice thing about flying airplanes is that the airplane never lies to you or suffers from confirmation bias. It just follows the laws of physics. The energy model is just so useful and it explains the duality created by energy of position (potential energy — altitude) and kinetic energy (speed). You just need to add to it the understanding the rate the aircraft “bleeds” (loses) energy, and the rate at which the engine replaces it.
The piece missing from the energy picture, and the thing that allows one to move from one energy state to another, is the ability of the wing to generate a force more-or-less orthogonal to the flight path, thus allowing us full control over the flight path, and the flow of energy from potential to kinetic and back again. That happens through the manipulation of the AoA with the elevator. The connector between the two is that, the more lift you request from the wing (greater AoA) the faster the aircraft bleeds energy that must be replaced with the engine. Eventually you reach a point where the engine cannot replace the energy fast enough to sustain the current energy state, i.e. you WILL go down or slow down.
You can view all this for yourself by going out and observing closely what you do when you control speed with power and altitude with power. The difference is in how you manipulate AoA and how you use trim, the AoA “cruise control”.
Autopilots that are without autothrottles, and autopilots that are without envelope control (I am talking about most older autopilots), can be used to illustrate what happens when you try to manipulate altitude with AoA changes and without concomitant power changes. These use AoA to adjust climb or descent because they depend on the fact that, when operating above L:D-max, and as speed decreases, drag decreases as well, making more energy from the engine available to cause the airplane to climb. it is interesting to turn on altitude hold when operating below L:D-max and then watch the AP stall the airplane when it decides it needs to climb for whatever reason. I know, we call this, “the area of reversed command,” but it is really just the point where drag is bleeding energy faster than the engine can make it up and something has to give. And even though it is most obvious at this point, this is true for the entire operating envelope of the aircraft.
Go play with your airplane but do so with critical observation to see how you manipulate things to control lift and energy.
Brian, I do it the same as you do – I think maybe you are not reading everything i say. Pitch to control altitude with coordinated power to control speed (like the autocouple/autospeed does). In some relatively extreme situations, such as a strong downdraft over the valley approaching Telluride, the most the pilot can do is go full power and pitch to Vx. The capability of the airplane will determine the rest.
Talking about authority, Chapter 4 is now in the Handbook and is the authoritive guideline, so am I to ‘let go’ of Chapter 4.
David: your point about massive power overcoming energy mismanagement is a good one. I would illustrate that by pointing out that the USAF Test Pilot School begins by retraining experienced jet pilots to understand energy management by requiring them to fly gliders. I discovered this because I took my initial glider training at Tehachapi where the USAF Test Pilot School out of Edwards AFB does their glider training.
It is also why I prefer to teach aerobatics in a less powerful aircraft that requires the pilot to manage energy better in order to fly aerobatics. The Extra 300 is a lovely airplane but it lets the pilot power through her mistakes better than something requiring a bit more finesse. The most challenging aircraft I use to fly aerobatics is my de Havilland Tiger Moth, which has so much drag (not countered with power) that it is extremely easy to run out of energy in a poorly-planned maneuver.
I hope to see all of you at OSH this year. I will be flying up in my Tiger Moth because … well, no reason other than I haven’t done it before. I am bringing a new primary student with me, one who has earned an EAA scholarship. I suspect that, by the time we return home, probably 25 flight hours later, he will be competent at cross-country pilotage and ready to solo. And, yes, he will understand power, energy, lift, and drag.
Brian – one of the best maneuvers, if not the best, for understanding energy limits is the accelerated stall. Unfortunately it isn’t required and as far as I know, often not included in training. David has been a big supporter of including this maneuver which is one of the four demonstration stalls recommended and I always do all four. I don’t understand why it isn’t required.
If you want an “FAA Enigma” why is a demonstrated crosswind ability not required? (we have to at least “discuss” the procedure – useful?)
David – 071322 8:24am comment – Wow, what a conversation – I get back to my inbox and there are five new comments (which I haven’t read yet).
David – “An F-35 can “make airspeed with throttle” in any direction (the throttle in a Champ is a “volume control”).”
Maybe it can make airspeed at any angle, but it can’t control altitude at any angle, as Barty Brooks found out. And that is why pilots should not be pitching to airspeed and trying to control altitude with power.
Isn’t this just getting down to one simple principle that has been there since day one. When full power is reached, airspeed is controlled by power (fixed power, pitch to airspeed). In that condition in normal maneuvering, never exceed a pitch that causes a loss of desired airspeed or said another way that causes an inadvertent stall.
Rich – “Re: Brian’s reference about stalls caused by the autopilot pitching for altitude.” I’m glad more about autopilots is getting included. The POH does cover this completely, where energy can be drained by setting a climb rate that drains airspeed/energy. Unfortunately, this is all located way in the back of the POH in the Supplement section. It’s something that has to be covered on the ground and demonstrated in the air.
David – “If you want an “FAA Enigma” why is a demonstrated crosswind ability not required? (we have to at least “discuss” the procedure – useful?)” Time constraints/scheduling/travel time. Useful to discuss – yes.
It can be a dilemma for instructors also for a rental checkout on a calm wind day. Luckily I didn’t have that happen. But I remember a conversation with a new student who already had a few hours and I thought he should by then have a good idea. I held a model airplane in several different positions as though it were on short final, then flaring, and asked what control inputs were needed. I got just about all incorrect answers. But he hadn’t soloed yet.
If I were doing a rental checkout on a calm wind day, I think the overall coordination and accuracy of the pilot would tell a lot. And I would have him/her do forward slips to landings. If he/she can’t do those I would assume the same for a crosswind landing. But there was one checkout where we used the crosswind runway and did a nice left crosswind landing, about a 10kt crosswind. I had the feeling we should land in the other direction with a right crosswind which we did. The first one definitely did not go well but we had the time to work on it successfully. He told me he didn’t realize there was so much difference in one’s orientation and inputs and was happy we did it.
As CFIs we do what is required but then some of us go beyond the requirements. My primary students are taught accelerated stalls, the Falling Leaf, cross-controlled stalls, pushovers (responding instinctively to a power failure by unloading), high-key/low-key power off landings beginning at a 3nm initial point from the airport, slipping and skidding turns, etc. I encourage them to add UPRT to their training as well.
Just because the PTS and ACS are so watered-down doesn’t mean we have to only teach to that level.
Brian, I’m trying to remember where I heard this before 🙂
Brian; I agree completely. In fact, if you haven’t read it I have a major article right here at SAFE aimed directly at instructors
“Flight Instruction at a Higher Level”
And that is the whole mission of SAFE; creating more professional educators of aviation!
This has been a great conversation. You have helped me to focus my thinking about the topic. Thank you David for starting it.
Looking forward to seeing everyone at Oshkosh. Look for my Silver and Yellow Tiger Moth, N8224, in her RAF livery from 1940. I use her to teach spins and tailwheel. Some tools are timeless.