Ex. 8 - Descending. What you will learn: How to descend at a variety of airspeeds and power settings to a desired altitude How to accurately level off.

Ex. 8 - Descending

Ex. 8 - Descending

Ex. 8 - Descending

What you will learn:

How to descend at a variety of airspeeds and power settings to a desired altitude

How to accurately level off at desired altitude and establish cruise

How to descend to a specified touch-down point.

OBJECTIVE

Ex. 8 - Descending

Why learn this?

As with climbs, different situations call for different types of descents

Even more variables to consider than for climb (power can be varied)

Accurate descents are even more important than accurate climbs.

MOTIVATION

Why?

Ex. 8 - Descending

Links

You already have understanding of:

attitudes and movements

power control

mixture and carburetor heat control

And you learned how make the plane go up…

And what goes up, must come

LINKS

down.

Ex. 8 - Descending

Let’s see how much you already know:Q What mixture setting should be used for descents?

Q What should be carb heat position in a descent?

Q What effect does reducing power have on yaw?

Q How does one control yaw after reducing power?

BACKGROUND KNOWLEDGE - TKT

Why?

Why?

Ex. 8 - Descending

Theories and Definitions

Power-off Descents (Gliding)

Gliding: Estimating Range

Power-on Descents

Power-on Descent Types

THEORIES & DEFINITIONS

Ex. 8 - Descending

x

Power-off Descents (Gliding)ATTITUDE + POWER = PERFORMANCE

What aspects of performance?

• airspeed (how fast we’re going)

• rate of descent (how fast we’re going DOWN)

HOW FAR WE CAN GLIDE

Distancexx x

Important assumption: NO WIND

When might gliding be useful?

THEORIES & DEFINITIONS

Where do we find the magical optimal number?

Where do we find the distance we can glide at that airspeed?

Gliding atdifferent speeds

too fasttoo slow just right

Ex. 8 - Descending

Gliding: Estimating RangeTHEORIES &

DEFINITIONS

What can the pilot do to stretch the glide?

Will the pilot make that spot?

ZERO WIND

Ex. 8 - Descending

Gliding: Estimating RangeTHEORIES &

DEFINITIONS

NOTHING!Plane is already flying at best gliding speed!

Raising the nose will:

• shorten your gliding distance

AND

• make your airspeed to dangerously low

NEVER TRY TO “STRETCH” A GLIDE.

Ex. 8 - Descending

Power-on DescentsTHEORIES &

DEFINITIONS

Normal descents are power-assisted

Power = more choice for performance +/- 100 rpm = +/- 100 feet per minute

or +/- 100 rpm = +/- 5 knots.

With power off, each airspeed corresponded to a set rate of descent

Now you change rate of descent and airspeed independently

How much power?

Ex. 8 - Descending

Power-on Descent TypesTHEORIES &

DEFINITIONS

Landing Approachstabilized descent at specific airspeed to touchdown at specific point

Enroute• no hurry to lose altitude• more comfortable for

passengers

Power setting

Carb heat

Airspeed

Flaps

Usually below green arc (about 1500-1900 rpm)

Above green arc (100-300 rpm below cruise power)

HOT COLD

See POH (55-65 knots in Cessna 150)

Close to cruise speed

Down (for better forward visibility and lower safe descent speeds)

Up (enroute descent done at high speed, low rate of descent – no need for additional lift and drag)

Ex. 8 - Descending

Procedures “Downwind” Check

Power-off Descent Entry

During

Approach Descent Entry

During

Enroute Descent Entry

During

Recovery from Descents Leveling out

Overshoot.

PROCEDURES

Ex. 8 - Descending

“Downwind” Check

Oil Temperature and Pressure in the green

Primer in and locked, Master ON, Mags on BOTH

Circuit Breakers in, Ammeter Needle right, Overvoltage Light OFF

Carb Heat hot, Mixture rich

Fuel ON, gauges show sufficient fuel

Flaps UP

Brake pressure.

PROCEDURES

Ex. 8 - Descending

Power-off Descent: EntryPROCEDURES

Power

Attitude

Trim

You have it down PAT

Cockpit check: oil T+P in the green, carb heat hot, mixture rich

Look-out!

• maintain cruise attitude until airspeed reaches best glide

• set descent attitude for that airspeed

• smoothly reduce power to idle

How will power reduction affect yaw?

• retrim airplane

Ex. 8 - Descending

Power-off Descent: DuringPROCEDURES

Keep good look-out

Maintain coordinated flight with rudder

Maintain straight flight with ailerons

Every 500 feet smoothly add full power, then reduce back to idle Why?

Ex. 8 - Descending

Approach Descent: EntryPROCEDURES

Power

Attitude

Trim

Cockpit check: oil T+P in the green, carb heat hot, mixture rich

Look-out!

• maintain cruise attitude until airspeed enters white arc

• once airspeed is “in white”, extend flaps

• set descent attitude for approach airspeed (see POH)

• smoothly reduce power to 1500-1900 rpm

• retrim airplane

Ex. 8 - Descending

Approach Descent: DuringPROCEDURES

Keep good look-out

Maintain coordinated flight with rudder

Maintain straight flight with ailerons

Control attitude and airspeed with pitch

Control descent rate with power.

Ex. 8 - Descending

Enroute Descent: EntryPROCEDURES

Power

Attitude

Trim

Cockpit check: oil T+P in the green, mixture rich

Look-out!

• establish descent attitude at near cruise airspeed

• smoothly reduce power to 100-300 rpm from cruise

• retrim airplane

Ex. 8 - Descending

Enroute Descent: DuringPROCEDURES

Keep good look-out

Maintain coordinated flight with rudder

Maintain straight flight with ailerons

Control attitude and airspeed with pitch

Control descent rate with power.

Ex. 8 - Descending

Leveling OutPROCEDURES

Power

Attitude

Trim

Continue look-out!

• return airplane to cruise attitude

• smoothly add power to approximately cruise setting

• carb heat cold

How will adding power affect yaw?

• retrim airplane

Begin leveling out at 10% of rate of descent If climbing up to 3500 feet at 300 feet per minute, begin leveling out at…

Ex. 8 - Descending

Overshoot!PROCEDURES

Power

Attitude

Trim

• flaps up to 20o

• set up a climb at 55 knots

• wait for +’ve rate of climb on VSI

• flaps up in stages

• full power

• carb heat cold

• retrim airplane.

Why retract some flap right away?

Why not retract all flap at once?

Ex. 8 - Descending

Considerations

Effect of Flaps

Effect of Wind.

CONSIDERATIONS

Ex. 8 - Descending

Effect of Flaps on DescentCONSIDERATIONS

More lift can safely descend at lower airspeeds

More drag steeper descent given same airspeed

More nose-down attitude better forward visibility given same

airspeed

Airspeed must bein white arc before flaps are extended!

Ex. 8 - Descending

Effect of WindCONSIDERATIONS

In headwind: can glide further by increasing airspeed slightly (offset effect of wind pushing you back)

In tailwind: can glide further by decreasing airspeed slightly (take advantage of lower rate of descent at slightly lower airspeed)

x

x xx

NO WINDHEADWINDTAILWIND

Ex. 8 - Descending

SAFETYSAFETY

! Cockpit check before all descents

! Carb heat: on for any descent at rpm below green arc

! Engine warm-up: every 500 feet during glides

! Glides: never try to “stretch”

! Flaps: airspeed must be “in the white”

! Constant look-out! (for other traffic and obstacles.)

Ex. 8 - Descending

Review:

Q What is your airplane’s best glide speed?

Q During an approach to landing your intended touchdown spot is drifting up. What does that mean and how do you fix the situation?

Q Same as above, but the spot is drifting down.

REVIEW

What is its significance?

Ex. 8 - Descending

Conclusion: As you can see, even seemingly simple procedures

involve a lot of details and considerations. But all the different procedures and considerations are related, and we keep coming back to the basic principles from earlier lessons.

Today you learned about one of the most fundamental and important flying skills. After practicing this lesson, you will be well on your way towards learning to land!

Read for next lesson: Ex. 9 – Turns.

CONCLUSION