Property of Lear Siegler 1. 2 PHYSICS OF THE ATMOSPHERE 3

Property of Lear Siegler

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PHYSICS OF THE ATMOSPHERE

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TERMINAL LEARNING OBJECTIVE

At the completion of this lesson, the student will:

ACTION: Demonstrate an understanding of theatmosphere’s physical properties and their impacton the operation of the TH-67 pressure instruments.

CONDITION: In a classroom environment giveninformation on the pressure instruments and the atmosphere.

STANDARD: Answer questions pertaining to theatmosphere’s physical properties and their impact on the operation of the TH-67 pressure instruments. Receive a “GO” by correctly answering the required number of questions on criterion referenced examination 011-0050.

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A: Enabling Learning Objective

Action: Identify the characteristics of the standard atmosphere

Condition: Given information about the standard atmosphere

Standard: IAW FM 3-04.240 and FAA-H-8083-25A,Pilot’s Handbook of Aeronautical Knowledge.


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The “Standard Atmosphere”

“A hypothetical vertical distribution of atmospheric temperature, pressure, and density which by

international or national agreement is taken to be representative of the atmosphere for the purpose

of altimeter calibrations, aircraft design, performance calculations, etc.”


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29.9

2”


53,000

18,000Sea Level 50%

90%

Sea Level

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MSL 29.92”Hg

1000’ 28.92”Hg

2000’ 27.92”Hg

3000’ 26.92”Hg

4000’ 25.92”Hg

5000’ 24.92”Hg

Standard Pressure Lapse Rate

1” Hg per 1000’


7500’ 22.42”Hg

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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

Standard Temp Lapse Rate

2°C per 1000’


7500’ 0°C

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29.92”Hg 15°C

AIR DENSITY

29.92”Hg 15°C29.92”Hg 15°C 28.92”Hg 15°C29.92”Hg 23°C


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AIR DENSITY

Press

Hum

Temp

Good Bad

H

L

L

L

H

H

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Property of Lear SieglerProperty of Lear Siegler

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B: Enabling Learning Objective

Action: Identify the pressures used in the pitot static system

Condition: Given information about the pitot static system pressures

Standard: IAW FM 3-04.240


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Weight of a column of airStatic Pressure --

Impact Pressure -- Static + Dynamic


Dynamic Pressure – Additional pressure caused by aircraft in motion

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Static pressure only

Impact pressure = Static + Dynamic


Note: Impact = Ram = Total = Pitot Pressure

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LEFT

PITOT TUBE

RIGHT

STATIC VENTS


HEATER

Construction of the Pitot System

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Notice that the Pitot Tube goesonly to airspeed indicator!

The Static Pressure is ventedto all three instruments.

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The diaphragm in the Airspeed Indicatoris connected to the Pitot Tube. It

only senses Pitot Pressure. The caseis vented to Static Pressure.

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The diaphragm in the Vertical Speed Indicator is vented to Static Pressure.The case is vented to Static Pressure

through a calibrated leak.22


The aneroids in the Altimeter are sealed. The case is vented to Static Pressure.

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C: Enabling Learning Objective Action: Identify the operational characteristics of the airspeed indicator

Condition: Given information about the airspeed indicator



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AIRSPEED INDICATOR


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LEFT

PITOT TUBE

RIGHT

STATIC VENTS


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STATIC VENTPITOT TUBE


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Impact pressure = Static + Dynamic


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??

?? ?

?

?

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D: Enabling Learning Objective Action: Identify the uses of the airspeed indicator

Condition: Given information on the uses of the airspeed indicator



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Uses for the airspeed indicator


1: Keep aircraft within “Never Exceed Speed"

2: Determine best operational speed for best climb, best endurance, and best range

3: Determine rate of movement for navigation

4: Aircraft attitude

Airspeed fast-Pitch attitude low

Airspeed low-Pitch attitude high34


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E: Enabling Learning Objective

Action: Identify the errors associated with the airspeed indicator

Condition: Given information about airspeed indicator errors



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ERRORS

Instrument Error – Minor, caused by friction


Installation Error – Caused by misalignment of the pitot tube and/or the static vents with the relative wind

Density Error – Caused by changes in air density

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F: Enabling Learning Objective

Action: Identify the types of airspeed

Condition: Given information about types of airspeed



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Types of Airspeed

TAS – True Airspeed - Calibrated Airspeed corrected for density error

CAS – Calibrated Airspeed – Indicated Airspeed corrected for installation error


IAS – Indicated Airspeed – read from the airspeed indicator

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Estimating True Airspeed

True Air Speed (TAS) increases over Indicated Air Speed (IAS) at the rate of two percent per thousand feet

“Aircraft climbing at a constant IAS will be increasing its velocity or TAS because of decreasing air density.” FM 3-04.203

REMEMBER…True airspeed will always be more than IAS with altitude!


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TRUE AIRSPEED (TAS) IS THE SAME,AIR IS LESS DENSE AT ALTITUDE,

THEREFORE, CALIBRATEDAIRSPEED (CAS) IS LESS THAN TAS.

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CAS IS THE SAME, AIR ISLESS DENSE AT ALTITUDE, THEREFORE,

TAS IS MORE THAN CAS AT ANYALTITUDE ABOVE

ZERO FEET DENSITY ALTITUDE.

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Airspeed Indicator in Review…


Can you identify the pressures used, the errors and the types of airspeed?

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G: Enabling Learning Objective

Action: Identify the operational characteristics of the vertical speed indicator

Condition: Given information about the operation of the vertical speed indicator



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Vertical Speed Indicator


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LEFT

PITOT TUBE

RIGHT

STATIC VENTS


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PITOT TUBE

STATIC VENTS


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CalibratedCalibratedLeakLeak

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H: Enabling Learning Objective

Action: Identify the uses of the vertical speed indicator

Condition: Given information about the uses of the vertical speed indicator



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Uses of the vertical speed indicator


1: Determine rate of climb or descent

2: Trend instrument-shows attitude changes immediately when in level flight

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Vertical Speed IndicatorPreflight Check


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I: Enabling Learning Objective

Action: Identify the errors associated with use of the vertical speed indicator

Condition: Given information about vertical speed indicator errors



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Errors of the vertical speed indicator


1: Six to nine second lag when leveling off from a climb or descent caused by the calibrated leak

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Errors of the vertical speed indicator


1: Six to nine second lag when leveling off from a climb or descent caused by the calibrated leak

2: Erratic in rough air

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Vertical Speed Indicator in Review…


Can you identify the pressures used, the errors and preflight procedures?

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J: Enabling Learning Objective

Action: Identify the operational characteristics of the altimeter

Condition: Given information about the operational characteristics of the altimeter



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ALTIMETER


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LEFT

PITOT TUBE

RIGHT

STATIC VENTS


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PITOT TUBE

STATIC VENTS


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Aneroid wafers sealed at factory

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Dial – three pointersHow to Read How to Read 75

10,000’ IndicatorTick marks in increments of 2000’

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1,000’ IndicatorTick marks in increments of 200’

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100’ IndicatorTick marks in increments of 20’

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1,040’

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8,000’

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18,980’

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Questions?


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Kollsman window – corrects for atmospheric pressure changes

28.00”Hg to 31.00”Hg83

Set field elevation

ATIS – “Altimeter setting three zero two four”

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1”Hg change = 1000’change in altitude .10”Hg change = 100’ change in altitude .01”Hg change = 10’ change in altitude

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AIMS Counter Drum Pointer

ATC Radar Beacon System

Identification Friend or Foe

MARK 12

SYSTEM

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K: Enabling Learning Objective

Action: Identify the uses of the altimeter

Condition: Given information about the uses of the altimeter



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Uses of the altimeter


Terrain clearance – MEF & OROCA

Vertical separation – Hemispherical Rule

Attitude control – Instrument Flying

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L: Enabling Learning Objective

Action: Identify the types of altitude

Condition: Given information about the types of altitude



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Identify the types of altitude

a. Indicated

b. True

c. Absolute

d. Pressure (PA)

e. Density (DA)


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Indicated Altitude

Read from instrument with correctly set Kollsman window (sea level pressure).


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True Altitude – Altitude above Mean Sea level

MSL

1000’


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MSL

Absolute Altitude– Altitude above the surface (AGL)


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MSL

Pressure Altitude (PA) – Altitude above the standard datum plane

29.92 Standard datum plane

1000’


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Max torque available, max gross weight,and performance are all

affected by Density Altitude


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Density Altitude (DA) : Is the densitycorresponding to a given altitude

in a standard atmosphere.

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Density Altitude (DA) : Pressure Altitude corrected for non standard temperature


DA = PA + (120 Tv )

PA = Pressure AltitudeTv = Temperature Variation

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Mean Sea Level (MSL)MSL 29.92”Hg 15°C

1000’ 28.92”Hg 13°C

2000’ 27.92”Hg 11°C

3000’ 26.92”Hg 9°C

4000’ 25.92”Hg 7°C

5000’ 24.92”Hg 5°C

7500’ 22.42”Hg 0°C


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29.92”Hg 15°C 29.92”Hg 32°CMSL

2040’ PA


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29.92”Hg 15°C 29.92”Hg 32°CMSL

2040’


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PA = 0’

OAT = 36°DA = 2500’


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DA = PA + (120 Tv )

PA = Pressure AltitudeTv = Temperature Variation

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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C

PA = 3000’

OAT = 0°C

Stand Temp = 9°C

Tv = OAT - Stand TempTv = 0° - 9°

Tv = -9°

2. Determine Temp Variation (Tv )

DA = PA + (120 Tv )1. Determine Standard Temp for

3000’

DA = 3000’ + (120 X - 9 )DA = 3000’ + (-1080 )DA = 1920’


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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C PA = 6000’

OAT = 5°C

OAT is Higher than standardDA is Higher than PA


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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C

PA = 4000’

OAT = 5°C

OAT is Lower than standardDA is Lower than PA


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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C

PA = 5000’

OAT = 5°C

DA = PA +120’


One hour later

OAT = 6°C

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PA AND STAN TEMP

HIGHER THAN STAN TEMP

LOWER THAN STAN TEMP

DA = PA + (120’ TV)

DA HIGHER THAN PA

DA LOWER THAN PA

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M: Enabling Learning Objective

Action: Identify the errors associated with the use of the altimeter

Condition: Given information about altimeter errors



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Altimeter errors

a. Instrument / Mechanical Error

b. Pressure Error

c. Temperature Error


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MSL

TrueAltitude

1000’


Instrument Error

1000’

FieldElevation

Caused by friction inside instrument

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MSL

TrueAltitude

1000’


Instrument Error

30.24 hg”

“Altimeter three zero two four”

30.26-30.24

= .02= 20 foot error

1000’

FieldElevation

Maximum Error + / - 70 ft

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Pressure Error – caused when flying intoareas that have different altimeter settings than those set in the Kollsman window.

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TRUE ALT

TRUE ALT

IND ALTIND ALT


Pressure Error

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H LIT

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L HTI

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Temperature Error

MSL MSL

1000’ 1000’

Sta

ndar

d te

mp

29.92

28.92

29.92

28.92

Col

der

29.92

28.92

War

mer


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Temperature Error

MSL MSL

1000’ 1000’

Sta

ndar

d te

mp

29.92

28.92

29.92

28.92

Col

der

29.92

28.92

War

mer


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TRUE ALT

TRUE ALT

IND ALTIND ALT


Pressure Error

Sta

ndar

d te

mp

28.92

28.92

War

mer

29.92 29.92 29.92

28.92

Col

der

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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C

Indicated Altitude = 6000’

OAT = 20°C

True Alt. is Higher than Indicated


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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C


OAT = 5°C

True Altitude is lower than Indicated


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MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C


OAT = 5°C

Indicated Altitude = True altitude


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IALT, STAN TEMPAND STAN PRESSURE

HIGHER THAN STAN

LOWER THAN STAN

HIGH TO LOW, LOOK OUT BELOW,LOW TO HIGH, CLEAR THE SKY!

TALT HIGHER THAN IALT

TALT LOWER THAN IALT

LOW TO HIGH

TO LOWHIGH

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N: Enabling Learning Objective

Action: Identify pitot static system malfunctions

Condition: Given information about pitot static system malfunctions



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STATIC VENT PITOT TUBEProperty of Lear Siegler

Pitot Static System Malfunctions

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Altimeter – No change in indication

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VSI – Level off at zero

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Airspeed Indicator – opposite of clogged pitot tube

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The endThe end

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STOPSTOP

Abandon hope all ye who enter hereAbandon hope all ye who enter here

You are entering the hidden slide ZoneYou are entering the hidden slide Zone

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0C H 0 2

M N

248.2GD

TX

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UHF vs. VHF Frequency

Warm-up Time

Range

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Warm-up time

Mode C Switch

Code 1200

Lost Communications Code

LEFT

PITOT TUBE

RIGHT

STATIC VENTS


HEATER

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PA = 6000’

OAT = 5°C

DA is Higher than PAProperty of Lear Siegler

Is the DA higher or lower than PA

MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C

Standard temperatures

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PA = 4000’

OAT = 5°C

DA is lower than PAProperty of Lear Siegler

Is the DA higher or lower than PA

MSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C


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CAS IS THE SAME, AIR ISLESS DENSE AT ALTITUDE, THEREFORE,

TAS IS MORE THAN CAS AT ANYALTITUDE ABOVE

ZERO FEET DENSITY ALTITUDE.

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Temperature Error

MSL MSL

1000’ 1000’

Sta

ndar

d te

mp

29.92

28.92

29.92

28.92

Col

der

29.92

28.92

War

mer


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OAT = 20°C

True Alt. is Higher than Indicated

Property of Lear SieglerMSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C


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OAT = 5°C

True Altitude is lower than Indicated

Property of Lear SieglerMSL 15°C

1000’ 13°C

2000’ 11°C

3000’ 9°C

4000’ 7°C

5000’ 5°C

6000’ 3°C


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TRUE ALT

TRUE ALT

IND ALTIND ALT


Pressure Error

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Documents

Property of Lear Siegler 1. 2 PHYSICS OF THE ATMOSPHERE 3