Straight Descents and Descending Turns

Demonstrate and simultaneously explain how to establish, maintain, and level off from straight descents and descending turns, and analyze and correct common errors (AI.VIII.D.S1, S2). The evaluator must select at least one Task from Area VIII. This is the fundamental with the highest downstream consequence — it is the one that becomes the approach, the emergency descent, and the engine-out glide, and it is the one whose bad habits kill people at low altitude.

In a descent, weight no longer acts solely perpendicular to the flightpath — a component of it now acts along the flightpath. At the same time, induced drag decreases because less lift is being produced. Net effect: the airplane has excess thrust, so it accelerates unless you take power away. A power reduction is required to balance the forces if airspeed is to be maintained (AFH ch. 3). That is the mirror image of the climb argument, and teaching them as a matched pair is worth more than teaching them separately.

Per AFH ch. 3:

• Partial power descent — the normal way to lose altitude, also called cruise or en route descent. Use the AFM/POH airspeed and power setting for prolonged descent. Target descent rate 500 fpm. Preselect the airspeed, pitch attitude, and power combination and keep it constant.
• Descent at minimum safe airspeed — a nose-high, power-assisted descent for clearing obstacles into a short field. Speed per AFM/POH, normally no greater than 1.3 Vso. Expect a steeper-than-normal descent angle and be aware that a lot of power may be needed to accelerate if mushing or an excessive sink rate develops.
• Emergency descent — AFM/POH procedure; generally high drag, high airspeed, a specific configuration (power idle, propellers forward, gear extended, flaps retracted) and a specified airspeed, often including turns.

A glide is a controlled descent with little or no engine power; forward motion comes from gravity pulling the airplane along an inclined path, and descent rate is controlled by balancing gravity against lift (AFH ch. 3). Best glide airspeed is the speed at which the airplane travels the greatest forward distance for a given loss of altitude in still air — it occurs at the highest lift-to-drag ratio (L/Dmax). Any deviation above or below best glide increases drag and reduces the glide ratio. Glide ratio is just distance over altitude lost: 10,000 feet forward while losing 1,000 feet is 10 to 1.

1. Close the throttle (advance the prop lever if equipped).
2. Hold altitude with back pressure while the airspeed bleeds down to best glide (AFH ch. 3).
3. Once the speed stabilizes at best glide, set the attitude to hold it against the natural horizon, glancing in to verify.
4. Trim off all control pressure.

The instructor-depth part is why the back pressure is needed at all: as power is reduced, propeller slipstream over the horizontal stabilizer decreases, tail-down force decreases, and the nose drops immediately. To keep the attitude constant through the power change you must add simultaneous back pressure. This matters most in slick airplanes that do not want to lose speed — any nose-down deviation immediately buys back airspeed.

Because L/D ratio determines distance, and L/D is unchanged by weight — so variations in weight do not affect glide angle provided the pilot flies the proper airspeed (AFH ch. 3). What weight changes is which airspeed that is: a heavier airplane must fly a higher airspeed for the same glide ratio. Two identical-L/D airplanes of different weights gliding from the same altitude cover the same distance; the heavier one simply gets there sooner. Students routinely believe heavy means shorter glide; correct it once, properly.

The airspeed that maximizes time aloft by producing the lowest rate of altitude loss. It occurs at a lower airspeed than best glide and results in less distance traveled (AFH ch. 3). Use it when time in flight matters more than distance — the AFH's example is ditching at sea. It is generally a few knots less than best glide speed and is not often a published airspeed, so do not send a student hunting for it in the POH.

Never attempt to stretch a glide by applying back pressure and reducing airspeed below the recommended best glide speed — the AFH calls it "a cardinal rule of airplane flying" (ch. 3). It fails because best glide already is L/Dmax: slowing below it increases drag and steepens the glide, so the airplane lands shorter, not farther, and may stall and lose control in the attempt. The purpose of pitch control in the glide is to maintain L/Dmax, which may require fore or aft pressure. Teach this with primacy in mind — the instinct to pull toward a runway you cannot reach is powerful and has to be pre-empted.

Two changes happen at once (AFH ch. 3): design compensation for P-factor and slipstream remains even though those effects have disappeared with the power, so slight left rudder pressure is typically needed to stay coordinated in a glide; and slower airflow over the control surfaces means greater deflection is required for the same effect, so pedal pressures feel light.

The hazard: a student calibrated on powered flight applies excessive rudder, producing slips and skids. The AFH names two ways this kills — a low-level gliding steep turn during an engine failure, where excessive inside rudder plus increasing back pressure "can rapidly turn into an unrecoverable spin"; and a power-off landing approach where rudder pressure banks the airplane, the pilot applies opposite aileron to stop the bank while pulling, and a fully developed cross-control condition forms. A stall there "almost certainly results in a rapid and unrecoverable spin."

Ten percent of the descent rate, in feet — the same rule as the climb (AFH ch. 3). Descending at 1,000 fpm, lead by 100 feet.

Be ready for the follow-up, because the AFH's own two examples do not agree and a sharp student will catch it. The 10 percent rule is stated for the partial-power descent and the glide (100 feet at 1,000 fpm). But the practice-glide level-off example gives 100 feet at 500 fpm — that is 20 percent, not 10. The reconciling principle is in the AFH's own sentence: the amount of lead depends on the rate of descent and the desired airspeed upon completion of the level-off. That second example assumes a final airspeed higher than glide speed, so the airplane needs extra room to accelerate. Teach the rule as 10 percent as the baseline, more when you are also speeding up — don't teach two contradictory numbers and hope the student never notices.

At the lead point, add power to the level cruise setting; the nose tends to rise as power and airspeed increase, so control the pitch smoothly so the level-off completes at the desired altitude and airspeed. Recovering from a gliding turn to a straight glide, relax the back pressure you were holding for the turn or the airplane pitches up and loses airspeed — the AFH flags that this "requires considerable attention and conscious control adjustment."

The AFH lists three elements that force the nose down and increase glide speed in a gliding turn (ch. 3):

1. Decrease in lift due to the direction of the lifting force — the same vertical-component loss as any turn.
2. Excessive rudder inputs as a result of reduced flight control pressures — the light-pedal problem above.
3. The normal stability and inherent nose-down characteristic of the airplane with the power off.

Together they mean a gliding turn requires more back pressure than either a straight glide or a level turn, and they degrade control coordination. A student who transfers their level-turn back pressure directly into a gliding turn will end up fast and low, which is precisely the error that shows up on base-to-final.

The highest glide ratio occurs at maximum L/D, so drag-producing components — flaps, landing gear, cowl flaps — matter. When drag increases, a lower pitch attitude is required to maintain airspeed, which steepens the glide path and reduces the distance traveled (AFH ch. 3). To maximize distance, eliminate all drag-producing components if possible. The instructional framing: configuration is a decision about how much of your remaining distance you are willing to spend, and it should be spent deliberately, once the landing site is assured — not reflexively at the moment of the failure.

Tailwind: the airplane glides farther, because of higher groundspeed. Headwind: it does not glide as far, because of slower groundspeed (AFH ch. 3). It matters because it is the bridge between a memorized glide ratio and a real forced-landing decision: the ratio in the POH is a still-air number, and the student needs to leave your airplane knowing that "10 to 1" is an input to a judgment, not the judgment itself.

The AFH treats them as two different maneuvers (ch. 3). Actual complete power failure: hold best glide until it is time to reconfigure for the landing, and plan for a steeper approach than usual — a 10 percent lead (100 feet at a 1,000 fpm descent rate) should be sufficient to slow the descent before landing. Simulated power failure training: apply power as the 10 percent lead value appears on the altimeter, allowing a slow but positive power application to maintain or increase airspeed while raising the nose to stop the descent and re-trimming.

Teach the distinction explicitly, or the student learns "at 100 feet, add power," which is precisely the wrong lesson to have installed on the day the engine actually quits.

The AFH gives you the method, and it is the clearest example of teaching feel anywhere in the handbook (ch. 3). A stabilized power-off descent at best glide is the normal glide; have the student memorize the attitude and speed against the natural horizon and register the sounds of air over the structure, the forces on the controls, and the feel of the airplane.

The instructor's specific job: point out that increasing sound level means increasing speed and decreasing sound means decreasing speed. When the student perceives a sound change, they should cross-check the visual and pressure references. Have them use all three references — sound, visual, and pressure — consciously until experience builds, then stay alert to any variation in attitude, feel, or sound.

K4 is a named knowledge element — say the term, don't just do it. Integrated flight instruction is introducing every maneuver using both outside visual references and flight instruments from the first presentation, so the learner maneuvers equally well by either, with attention about 90 percent outside / 10 percent inside (AIH ch. 9).

In the descent the division of labor is unusually clean, which makes this the best Task to teach the concept on:

• Outside sets the attitude — the glide picture against the natural horizon, the wingtips for bank, and the chosen landing spot.
• Sound and feel run in parallel — the AFH's third channel, which no instrument gives you: rising sound means rising speed, and it arrives before the needle does.
• Inside validates — a glance at the ASI to confirm best glide, the VSI for rate, the altimeter for the level-off lead. Then straight back out, because in a real glide your eyes belong on the field.

The teaching point to say out loud: on the day the engine quits, the student will be outside almost the whole time. The instruments confirm the glide; they do not fly it. And the standard caution applies — this is not IMC training, and you must verify the learner understands it does not prepare them for marginal weather or IMC (AIH ch. 9).

Any glide conducted at a speed other than best glide (AFH ch. 3). You teach it after the student has a solid comprehension of the normal glide, because the point is contrast — showing what too fast and too slow actually look and sound like. The consequences to name: not making the intended landing spot, flat approaches, hard touchdowns, floating, overruns, and possibly stalls and an accident. A student who has only ever seen the correct picture has no way to recognize the incorrect one at 300 feet.

Thirteen errors (AFH ch. 3), grouped:

Entry technique

• Failure to slow to approximate glide speed before lowering the pitch attitude.
• Inadequate back pressure during glide entry, producing an overly steep glide.
• Failure to lower the pitch attitude entering a gliding turn, so airspeed decays.

Where they are looking

• Establishing or maintaining a normal glide solely by reference to flight instruments.
• Chasing the airspeed indicator — inability to stabilize the glide.
• Inability to sense airspeed changes through sound and feel.

Feet

• Slipping or skidding in gliding turns, not recognizing that rudder forces differ without power.
• Excessive rudder pressure during recovery from gliding turns.
• Cross-controlling during gliding turns near the ground — the one that has to be zero-tolerance.

Recovery and control

• Attempting to stretch the glide with back pressure.
• Inadequate pitch control recovering from a straight glide.
• Failure to hold a constant bank angle in gliding turns.

Everything else

• Failure to adequately clear for traffic in the direction of turn or descent.

Same sequence you briefed on the ground (AIH ch. 9):

• "Clearing turn — and this time I'm clearing below us, because that is where we are going."
• "Throttle back. Watch what happens to the nose when I do — it drops on its own. That's the slipstream leaving the tail, and I'm holding the attitude through it."
• "We are still level. I'm trading speed, not altitude, until we get to best glide."
• "Now the speed is there — nose goes here on the horizon. Take a picture."
• "Listen. That's the sound of best glide. If it gets louder, we're fast."
• "Left rudder — feel how light the pedals are? That's the whole reason we don't stomp on them close to the ground."
• "Trim. Now I'm holding nothing, and I can look outside for a field."
• "Level-off: 500 down, so I add power 100 feet early, and the nose will want to rise — I'm controlling that, then re-trimming."

Because everything the student practices here gets replayed at low altitude with an audience — on final, and someday with a dead engine.

Cross-control and the stall/spin chain. The AFH describes the exact sequence: excessive rudder banks the airplane, the pilot stops the bank with opposite aileron while pulling, and a full cross-control forms. A stall there "almost certainly results in a rapid and unrecoverable spin" (AFH ch. 3). NTSB data behind the AIH's distraction guidance says 60 percent of stall/spin accidents occurred during takeoff and landing, and 20 percent were preceded by engine failure (AIH ch. 9). Set a hard altitude floor for practice glides and gliding turns, brief it, and enforce it.

Collision hazards. A descent enters occupied airspace you cannot see through the nose in level attitude but can see through in a descent — the trade is that you are now converging with traffic below you. Clear before descending and keep clearing through it (AFH ch. 1).

Distraction and task prioritization. The AIH's most on-point sanctioned distraction here is asking the student to identify a field suitable for a forced landing while flying the glide — it trains the actual division of attention the maneuver exists for (AIH ch. 9).

Loss of situational awareness and disorientation. R1 names both and the descent supplies the textbook cases:

• Graveyard spiral. A prolonged constant-rate descending turn stops registering as a turn; on rollout the pilot feels a turn the other way, reads the descent as level, and pulls — which tightens the spiral and accelerates the altitude loss (PHAK ch. 17). This is the illusion behind the classic VFR-into-IMC descent accident, and the descending turn is where a student first meets its precursor.
• Somatogravic illusion, in reverse. A rapid throttle reduction — exactly how you enter a glide — decelerates the airplane and can leave the disoriented pilot pulling into a nose-up or stall attitude (PHAK ch. 17). Another reason to teach the smooth, deliberate power reduction rather than a chop.
• Positional SA. In a prolonged glide the student fixates on the field and stops tracking altitude, wind, and where the airport went. Make them call altitude remaining and the field aloud on a fixed interval; it converts SA from a hope into a procedure you can grade.
• The floor is an SA device too. A student who cannot tell you their altitude is a student who has already lost it — that answer, not just the altimeter, is your cue to take the airplane.

Your own limits. Guard the controls in every gliding turn below your floor. Take them with "I have the flight controls," do not leave the student on them during a recovery, and never let the student exceed your limits (AIH ch. 9).