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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