Late last year, the FAA published a revision of the Airplane Flying Handbook, one of the core texts used by people who are learning to fly. It is one of the two primary books we reference in our private pilot syllabus. The revision adds a new Chapter 4, Energy Management: Mastering Altitude and Airspeed Control. Before I begin my analysis of the new chapter, I’d like to take a moment to recognize that flight students include people of all ages and walks of life, with varied educational backgrounds. While a fair amount of knowledge is required to earn a pilot certificate, you should not need a PhD in physics to understand the Airplane Flying Handbook. Student pilots can solo at the tender age of 16, long before most teens have learned about the work of Sir Isaac Newton in school. Yet it appears the latest revision attempts to explain one of the most basic, and arguably one of the most important and safety critical principles of flight — energy management — in such an overly complicated way that the average flight student will quickly become frustrated, bored, disillusioned, and likely miss the point entirely.
On the first page of the new Chapter 4, the author writes: “This chapter is all about managing the airplane’s altitude and airspeed using an energy-centered approach. Energy management can be defined as the process of planning, monitoring, and controlling altitude and airspeed targets in relation to the airplane’s energy state in order to: 1) Attain and maintain desired vertical flightpath-airspeed profiles; 2) Detect, correct, and prevent unintentional altitude-airspeed deviations from the desired energy state; 3) Prevent irreversible deceleration and/or sink rate that results in a crash.”
That is a reasonable and respectable goal. But then, on that very same first page, the text descends into a morass of formulas:
The total mechanical energy of an airplane in flight is the sum of its potential energy from altitude and kinetic energy from airspeed. The potential energy is expressed as mgh, and the kinetic energy as ½ mV². Thus, the airplane’s total mechanical energy can be stated
mgh + ½ mV²
m = mass
g = gravitational constant
h = height (altitude)
V = velocity (airspeed)
A flying airplane is an “open” energy system, which means that the airplane can gain energy from some source (e.g., the fuel tanks) and lose energy to the environment (e.g., the surrounding air). It also means that energy can be added to or removed from the airplane’s total mechanical energy stored as altitude and airspeed.
Then, on page 3, more formulas and the first of many confusing graphics:
I don’t know who the author of this chapter is, but I’ll be willing to bet that he is not a flight instructor, or if he is, he’s a not a very good one. If I drew Figure 4-7 on a white board for a student, I can almost guarantee he would look at me like I was insane and walk out the door.
Neither of the previous editions of the Airplane Flying Handbook, published in 2004 and 2016, contained a section specifically dedicated to the subject of energy management. Interestingly, the 2004 edition contained a brief discussion of the relationship between pitch and power in Chapter 3, Basic Flight Maneuvers, but this was removed in the 2016 edition:
No discussion of climbs and descents would be complete without touching on the question of what controls altitude and what controls airspeed. The pilot must understand the effects of both power and elevator control, working together, during different conditions of flight. The closest one can come to a formula for determining airspeed/altitude control that is valid under all circumstances is a basic principle of attitude flying which states: “At any pitch attitude, the amount of power used will determine whether the airplane will climb, descend, or remain level at that attitude.”
The relationship between pitch and power is essential to understanding aircraft energy management. I also find it interesting that the 2004 and 2016 editions fail to discuss angle of attack until Chapter 4, Slow Flight, Stalls, and Spins, though the new 2021 edition references angle of attack in Chapter 1 and then again in Chapter 5, Maintaining Aircraft Control: Upset Recovery and Prevention (the chapter previously titled Slow Flight, Stalls and Spins). The 2004 edition does not even list angle of attack or lift as topics in the Index! The 2016 and the new 2021 edition both fail to mention lift in the Index. How is a student pilot supposed to understand how the wing works if he can’t jump to a prominent section in the book dedicated to defining and illustrating lift and angle of attack? In my opinion, the four forces of flight — lift, weight, thrust and drag — and angle of attack should be the very first thing discussed in this book! Instead, the FAA wastes several pages in Chapter 1 tooting its own horn, droning on about regulations.
Fortunately, there is a much better resource for understanding the fundamentals of flight. Stick and Rudder, An Explanation of the Art of Flying, was first published in 1944 by test pilot Wolfgang Langewiesche, who died in 2002 at the age of 95. It is widely considered by pilots to be one of the finest books ever written about how to fly an airplane. While Langewiesche’s writing style may not appeal to every reader, there are “golden nuggets” of wisdom in this book that every pilot should know.
In Chapter 3, Lift and Buoyancy, he explains how a pilot can judge an aircraft’s energy state in flight by observing its tendency to climb if the angle of attack is increased.
Continuing, then, our attempt to understand this myserious something that pilots call “lift,” we might try to call it “The Zoom Reserve.” A zoom is a very steep climb, so steep that the airplane can’t hold it as a steady condition but gradually slows up. As it slows up, the pilot must of course increase its Angle of Attack by bringing the stick back; otherwise the zoom would level out and stop. Thus a zoom, continued long enough, will always end in a stall. “I have lots of lift” may simply mean, then: “I have enough speed, and am flying at low Angle of Attack, so that if I started a zoom at this moment, I could make it long and steep before I would stall.” “I have very little lift” may mean: “I am in a flight condition which would lead to a stall almost right away if I started a zoom.”
Again, one might call this mysterious something the “Potential Excess Lift.” In steady flight, an airplane’s lift (real, engineering sort of lift, that is) is always just equal to its weight. But by pulling his stick back and thus holding his wings at higher Angle of Attack, the pilot can produce a surge of excess lift. The excess lift will then make the airplane’s flight nonsteady: it will balloon the airplane upward in an up-curving zooming flight path — perhaps the pull-up into a loop. “I have lots of lift” then means: “I am in a condition where, simply by pulling my stick back, I could double or triple my lift force if I wanted to, and could make this airplane shoot upward as if it had been given a tremendous kick from below.” “I have very little lift” means: “I am in a flight condition where I could get only a feeble surge of excess lift, and a feeble upward curving of my flight path even if I now pulled my stick all the way back.” And “I haven’t any lift at all” would mean: “I am in a flight condition where, if I pulled the stick back a little farther, no additional lift would be produced, but on the contrary the wings would stall and the lift would be reduced and the ship would fall.”
This is precisely what a pilot needs to understand in order to make safe, smooth landings. This is why we practice slow flight and stalls at a safe altitude, so that students can learn to feel and sense when the aircraft is flying at the edge of a stall.
In Chapter 5, The Law Of The Rollercoaster, Langewieche explains energy management using an earthbound experience most people can relate to:
In an airplane, “slow” and “fast,” “high” and “low,” “up” and “down,” “lift” and “drop” are tied up with each other in a particular fashion. You can always get one by paying for it with the other. You can never get rid of one without getting a lot of the other. …The handiest comparison we have is at the amusement park — the roller coaster.
A roller coaster starts out by being high — having been hauled to the top of the track by some mechanical hoist. And it starts out, on the top of the hump, by having very little speed. Then it cuts loose, and in going down it converts altitude into speed; the steeper and farther it goes down, the more speed it picks up. At the bottom, it has no altitude, but plenty of speed; and it presently proceeds to convert speed back into altitude by shooting up the next incline. At the top, it is almost out of speed; but it has almost all of its original altitude again. And then it goes down another slope.
The same thing is true when an airplane glides with the engine throttled back; speed and height are two forms of the same thing. “Of course they are,” says the physicist. “they are two different forms of energy.” When a pilot maneuvers, he continually makes exchanges, turning altitude into speed or speed into altitude; and he makes those exchanges whether he wants to or not.
Airshow pilots understand this concept of energy exchange and put it to work when performing their routines. If you ever go to an airshow, you will likely hear the announcer say the pilot is “trading airspeed for altitude” when pulling up from a dive. Watch this video, filmed at EAA AirVenture 2014, showing an airshow pilot performing aerobatics in a light taildragger with the engine shut down:
Of course, no pilot on the planet understood energy management better than Bob Hoover:
I share these videos not to suggest that you go out and practice aerobatics in one of our aircraft — don’t even think about it. However, even a novice student pilot can learn much about aircraft control and energy management by observing an air show routine, particularly a classic routine, using basic loops, rolls and spins, performed in a stock airplane, not a hotrod.
In any case, for the rest of us who are not air show pilots, the only phases of flight where proper energy management really matters from a practical safety standpoint is during takeoff and landing. The FAA should have scrapped the new Chapter 4 and instead beefed up Chapter 9, Approaches and Landings. According to FAA and NTSB accident data, this is where pilots are screwing up the most. Check out this video of a student pilot stalling while attempting a go-around after a bad landing:
And it isn’t just student pilots who end up on the accident docket. Two recent crashes involving professional flight crews flying expensive business jets illustrate that poor energy management during the approach and landing phase is to blame for nearly all fatal airplane accidents. (For more information on these, see this NTSB animation of the 2017 Learjet crash in Teterboro, NJ and this independently created animation of the 2021 Learjet crash in El Cajon, CA.)
In Chapter 9 of the Airplane Flying Handbook, the FAA defines a stabilized approach:
A stabilized approach is one in which the pilot establishes and maintains a constant-angle glide path towards a predetermined point on the landing runway. It is based on the pilot’s judgment of certain visual clues and depends on maintaining a constant final descent airspeed and configuration. An airplane descending on final approach at a constant rate and airspeed travels in a straight line towards a spot on the ground ahead, commonly called the aiming point. If the airplane maintains a constant glide path without a round out for landing, it will strike the ground at the aiming point.
… The round out, touchdown, and landing roll are much easier to accomplish when preceded by a stabilized final approach, which reduces the chance of a landing mishap.
For a typical GA piston aircraft in a traffic pattern, an immediate go-around should be initiated if the approach becomes unstabilized below 300 ft AGL.
The handbook’s first criteria for a stabilized approach is being established on a 3-degree glide path.
The problem with this focus on maintaining a 3-degree glide path, or using this to define “stable” is that a power-off approach typically will result in a steeper glide path, as illustrated later in the chapter during the discussion of short-field approaches and landings. Is the author implying here that anything other than a 3-degree approach is unstable? I hope not.
If you haven’t seen this now classic YouTube video published by AvWeb editor Paul Bertorelli, please watch it now before reading further:
When describing the technique for landing on a relatively short runway, the AFH states:
To land within a short field or a confined area, the pilot needs to have precise, positive control of the rate of descent and airspeed, and fly an approach that clears any obstacles, results in little or no floating during the round out, and permits the airplane to be stopped in the shortest possible distance. When safety and conditions permit, a wider-than-normal pattern with a longer final approach may be used. This allows the pilot ample opportunity to adjust and stabilize the descent angle after the airplane is configured and trimmed. A stabilized approach is essential.
Flying a huge pattern is poor technique and, to Bertorelli’s point, teaches students that you can’t make a stabilized power off approach to a short field at idle using a normal traffic pattern. If you have to, as he says, “stuff your airplane into a parking lot” after the engine quits, you may not have the luxury of flying a wide pattern or a longer final approach. Here in Jacksonville, most of our runways are so long you could land a Cessna 150 on them twice and still have room to go around. When I was teaching up in the Washington, DC area, our flying club was based out of Montgomery County Airpark, which had a single 4,200-foot runway, about the same length as Craig. We also based some aircraft at nearby Davis Field, which had a 2,000-foot runway. During training, we routinely landed on runways that were less than 3,000 feet long. One of our favorite things to do was to take our students to nearby Clearview Airpark (2W2, runway length 1,800 feet) for a real short-field landing right before their private pilot check ride, and buy them this mug as a confidence building reward.
Back to the Airplane Flying Handbook. Look, I don’t think the entire book is garbage, just the new Chapter 4 on energy management. Reviewing Chapter 9, Approaches and Landings, the FAA attempts to describe the process of landing as a series of steps, including the “round out” or “flare.” Before continuing on, you may want to read my earlier blog post, Flare Is A Four-Letter Word.
Round Out (Flare)
The round out is a slow, smooth transition from a normal approach attitude to a landing attitude, gradually rounding out the flightpath to one that is parallel to and a few inches above the runway. When the airplane approaches 10 to 20 feet above the ground in a normal descent, the round out or flare is started. Back-elevator pressure is gradually applied to slowly increase the pitch attitude and AOA. [Figure 9-10] The AOA is increased at a rate that allows the airplane to continue settling slowly as forward speed decreases. This is a continuous process until the airplane touches down on the ground.
When the AOA is increased, the lift is momentarily increased and this decreases the rate of descent. Since power normally is reduced to idle during the round out, the airspeed also gradually decreases. This causes lift to decrease again and necessitates raising the nose and further increasing the AOA. During the round out, the airspeed is decreased to touchdown speed while the lift is controlled so the airplane settles gently onto the landing surface. The round out is executed at a rate such that the proper landing attitude and the proper touchdown airspeed are attained simultaneously just as the wheels contact the landing surface.
The rate at which the round out is executed depends on the airplane’s height above the ground, the rate of descent, and the pitch attitude. A round out started excessively high needs to be executed more slowly than one started from a lower height. The round out rate should also be proportional to the rate of closure with the ground. When the airplane appears to be descending very slowly, the increase in pitch attitude should be made at a correspondingly slow rate. The pitch attitude of the airplane in a full-flap approach is considerably lower than in a no-flap approach. To attain the proper landing attitude before touching down, the nose needs to travel through a greater pitch change when flaps are fully extended. Since the round out is usually started at approximately the same height above the ground regardless of the degree of flaps used, the pitch attitude should be increased at a faster rate when full flaps are used. However, the round out should still be executed at a rate that takes the airplane’s downward motion into account.
Once the actual process of rounding out is started, the pilot should not push the elevator control forward. If too much back-elevator pressure was exerted, this pressure is either slightly relaxed or held constant, depending on the degree of the error. In some cases, it may be necessary to advance the throttle slightly to prevent an excessive rate of sink or a stall, either of which results in a hard, drop-in type landing. It is recommended that a pilot form the habit of keeping one hand on the throttle throughout the approach and landing should a sudden and unexpected hazardous situation require an immediate application of power.
The touchdown is the gentle settling of the airplane onto the landing surface. The round out and touchdown are normally made with the engine idling. During the round out, the airspeed decays such that the airplane touches down on the main gear at or just above the approximate stalling speed. As the airplane settles, proper landing attitude is attained by application of whatever back-elevator pressure is necessary. Some pilots try to force or fly the airplane onto the ground without establishing proper landing attitude. The airplane should never be flown onto the runway with excessive speed. A common technique to making a smooth touchdown is to actually focus on holding the wheels of the aircraft a few inches off the ground as long as possible using the elevators while the power is smoothly reduced to idle. In most cases, when the wheels are within 2 or 3 feet of the ground, the airplane is still settling too fast for a gentle touchdown. Therefore, this descent is retarded by increasing back-elevator pressure. Since the airplane is already close to its stalling speed and is settling, this added back-elevator pressure only slows the settling instead of stopping it. At the same time, it results in the airplane touching the ground in the proper landing attitude and the main wheels touching down first so that little or no weight is on the nose-wheel.
This is all well and good, but does not sufficiently explain how a pilot is supposed to sense and evaluate whether he is carrying the appropriate amount of energy during the approach, or how to adjust for various situations. For example, if I’m flying one of our Cessna 172s into Craig and the controller asks me to “keep my speed up on final” because there is a King Air behind me on the ILS, I’m not going to slow down to 65 knots with full flaps. I could say “unable” and really annoy both the controller and the King Air driver, but I’m not going to. Why? Because I’m not a “one trick pony pilot” and I’m proud of that. I have learned to manage the airplane’s energy such that I can choose to fly my final approach at a wide variety of airspeeds and glide profiles to accommodate various situations. And you should too.